Iron oxide color

Iron oxides are a type of chemical compounds composed of iron and oxygen. In total, sixteen known iron oxides and oxyhydroxides are present. There lies a great variety of usage for these various oxides and hydroxides ranging from pigments in ceramic glaze, to use in thermite.

Hematite is a key ore of iron and its blood red color (in the powdered form) provides itself well to use as a pigment. The name Hematite is derived from a Greek word meaning blood-like because of the color of its powder. There exists ancient superstition which tells that big deposits of hematite were formed from battle fought in ancient times by the blood that flowed into the ground. Crystals of Hematite are thought to be rare and are desired by collectors as are fine Kidney Ore specimens.

Properties of iron oxide

The color ranges from steel or silver gray to black in some forms and red to brown in earthy forms. Occasionally it is tarnished with gleaming colors when in a hydrated form (called Turgite).The luster is metallic or dull in earthy and oolitic forms. Transparency: Crystals are opaque. Crystal System is trigonal; bar 3 2/m Crystal Habits include tabular crystals of varying thickness sometimes twinned, micaceous (specular), botryoidal and massive. also earthy or oolitic. Cleavage is absent.

However, there is a parting on two planes.

Fracture is uneven. Hardness is 5 – 6. Specific Gravity is 5.3 (slightly above average for metallic minerals). Streak is blood red to brownish red for earthy forms. Associated Minerals include jasper (a variety of quartz) in banded iron formations (BIF or Tiger Iron), dipyramidal quartz, rutile, and pyrite among others.

Forms of iron oxide

Iron Oxide is present in many different forms which are mentioned below:

a. Alpha phase- In the Alpha phase, most common form is Rhombohedric, and occurs as the mineral hematite.

b. Beta Phase- The Beta phase is cubic face centered or metastable.

c. Gamma Phase- The Gamma phase is cubic, metastable.

d. Epsilon phase- The Epsilon phase is rhombic and has properties in between the alpha and the gamma phases.

Iron ore slag

Introduction :

The process of preparing iron from its ores was discovered very early, certainly before the thirteen century B.C. perhaps the metal was found in the ashes of a fine built on a outcrop of iron ore, such as hematite, magnetite, or siderite.  The ore would have been reduced by charcoal at the high temperature of the fire to yield iron. Iron is produced in blast furnace by a similar reduction.

A mixture of iron ore, coke (carbon produced by heating coal), and lime stone is added at the top of the furnace, and a blast of heated air enters at the bottom.Near the bottom of the furnace, the coke burns to the carbon dioxide.  As the carbon dioxide rises to the heated coke, it is reduced to carbon monoxide. The carbon monoxide then reduces the iron oxides in the iron ore to metallic iron. The overall reduction of hematite can be written:
                         Fe₂O₃ (s) + 3CO(g) → 2Fe(l) + 3CO₂(g)

Description to iron ore slag

Molten iron flows at the bottom of the blast furnace, where it is drawn off.Impurities in the iron ore react with calcium oxide from the lime stone to produce a glassy material called slag. Molten slag collects in a layer floating on the molten iron and is drawn off periodically. Steals are alloys containing over 50% iron and up to about 1.5% carbon.The iron obtained from a glass furnace contains a number of impurities including 3% to 4% carbon, that make it brittle.

To produce steal, you must removed these impurities and slag and reduced the carbon contents of the iron.The basis oxygen process is a method of making steal by blowing oxygen into the molten iron oxidize impurities and decrease the amount of carbon present.Other metals may be added to the steal to give it desired properties.Stainless steels, for example, contain 12% to 18% chromium and 8% nikle.

Molten iron

Introduction :

Let us first be aware of the element iron, and then we can discuss more about molten iron. It is a chemical element with the atomic number 26 and its reperesentation is done by the formula 26. Mostly, it is available in the two forms, i.e., +2 and +3 oxidation states. It is one of the most common element which is available in plenty on the earth's crust. It is produced by the fusion of heavy metal elements mostly found on the surface of stars. Iron and its all form of alloys are regarded as the ferromagnetic elements.

Basically, molten iron is obtained in the blast furnace. Basic fetaure of blast furnace is that we need to remove oxygen as well as the impurities to obtain the iron in its pure form.

The various steps of blast furnace are as follows :
The main sources of iron ore are haematite(Fe₂O₃http://drupal.mathcontent.com/node/60928/edit) and magnetite(Fe₃O₄). 

(1) First of all, we need to add Charcoal, limestone, iron ore and coke from the top of the blast furnace.

(2) Next, the inserted charge gets heated and dried by the hot gases which is blown through the furnace.

(3) Thus, there is formation of the molten iron which starts melting down from the inside surface of the molten iron.

(4) As there is insufficient supply of oxygen in the blast furnace, so, mostly there is formation of carbon monoxide only.

(5) Thus, molten iron and slag is drawn out from the blast furnace on a periodic basis.
 

The various reactions of blast furnace are :
(1) 3Fe₂O₃ + CO -> CO₂ + 2Fe₃O₄  ( at a temp. of 850⁰F )

(2) Fe₃O₄ + CO -> CO₂ + 3FeO   ( at a temp. of 1100⁰F )

(3) FeO + CO -> CO₂ + Fe   or      ( at a temp. of 1300⁰F )
      FeO + C -> CO + Fe                     ( at a temp. of 1300⁰F )

(4) CaCO₃ -> CaO + CO₂

(5) C + O₂ -> CO₂ + Heat

Image of molten iron :

Applications of molten iron :

Molten iron is basically used in two kinds of applications :

(1) Metallurgical - It is used in the various engineering applications like construction of machinery tools, automobile parts, used as a pillar in the construction of buildings. Pure iron being very soft can't be used for these purposes, so mostly it is used in the form of steel which is quite hard and can be used for purposes.

(2) Iron is used as a catalyst in the various chemical processes like the production of ammonia in the Haber-Bosch process.

(3) Iron also has a biological importance as it is required by all the living organisms for their healthy growth.

Disadvantages of molten iron :

(1) Intake of high amount of iron content in the body can lead to the damage of body parts like DNA, proteins, lipids etc.

(2) There can be also damage to the cells of gastro-intestinal tract, coma and various heart related diseases.

Iron compounds

Introduction 

Iron has atomic number 26 and mass number 55.847.  Iron has oxidation states +2, +3.  Iron compound has electronic configuration [Ar] 4s², 3d⁶.  Iron belongs to d-block element group also called transition metal group.  Iron belongs to Group 8 and Period 4 in the periodic table.  Iron is the fourth most abundant element on earth and the most common ferromagnetic material in everyday use.  Fresh iron compound appear silvery gray.

In ancient days Iron was used but not before copper related alloys or bronze.  Pure iron is softer than aluminium but it is strengthened by adding impurities.  Iron compound is a strong metal which is widely used in construction purposes such as building houses, complex etc.  Steel is 1000 times stronger than iron.  Iron compound is smelted in blast furnace, where ore is reduced by coke to metallic iron.  Elemental iron is very reactive; it oxidizes in air to give iron oxide, also called as Rust.  Iron compounds form binary compounds with halogen and the chalcogens.

In organometallic chemistry, Ferrocene was the first sandwiched compound discovered.  Iron compounds forms complex with di oxygen as haemoglobin and myoglobin; these two compounds are very important common oxygen transport protein in vertebrate.  Iron oxide mixed with Aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ore.

Features of iron compounds

1)      Atomic radius and ionic radius of Group 8 elements: A.R. and I.R. increases down the group.

Elements	Fe	Ru	Os	Uno
A.R.  (pm)	126	134	135	-
I.R. (pm)	(+2)=77, (+3)=63	82	-	-

Where A.R.  (pm) = Atomic radius in pico meter.
              I.R.  (pm) = Ionic radius in pico meter.

2) Ionisation energy (I.E.) in Iron compound:
       1^st I.E.    =     759.3 KJ/mol.
       2^nd I.E.   =    1561.1 KJ/mol.
       3^rd I.E.    =    2957.3 KJ/mol.

3)      Non-metallic properties of Iron Compound: Iron is a metal which is a chemical element is good conductor of electricity and heat and forms cations with ionic bonds with non-metals.

4)      Melting points (M.P.) and Boiling points (B.P.) of Group 8 elements:

Elements	Fe	Ru	Os	Uno
M.P.  (0C)	1808	2810	3300	-
B.P.  (0C)	3023	4425	5300	-

5)      History of Iron compounds: Iron artifacts have been found around 3000 B.C.  A remarkable iron pillar dating about A.D.  400 is standing today in Delhi.

6)      Ores of iron compounds: Iron ores are rich in Iron oxide and vary in colour from dark grey, bright yellow, deep purple to rusty red.  The iron compound itself found in the form of

a)      Magnetite (Fe₃O₄).

b)      Hematite (Fe₂O₃).

c)      Goethite (FeO(OH))

d)     Limonite (FeO(OH).n(H₂O))

e)      Siderite (FeCO₃).

Hametite is a natural ore.  Hametite refers to early days mining.  The raw material used to make pig iron is iron ore.  The pig iron is the main raw material to make steel. 98% of mined ore is used to make steel.

Uses of Iron compounds: By adding impurities, Steel is produced.  Steel is widely used to make stainless steel plates and other various utensils.

Example of iron compounds: Iron 2 chloride

Iron 2 chloride is also called as Ferrous chloride. Its chemical formula is FeCl₂. Iron 2 chloride has high Melting point. It is a paramagnetic solid and is obtained in the form of an off-white solid. Iron 2 chloride crystallizes from water as the greenish tetrahydrate, which is used in laboratory uses and other applications. The compound is also soluble in water; aqueous solutions of Iron 2 chloride is yellow in color.
Molecular Formula of Iron 2 Chloride is FeCl₂. 4H₂O

Properties of Iron 2 chloride

Chemical properties:
 • Iron 2 chloride is Highily Corrosive substance.
• It readily causes burns.
• Inhalation of Iron 2 chloride is dangerous and touching with skin and swallowing of Iron 2 chloride is also harmful.
• Iron 2 chloride may lead to possible mutagen.

Physical properties:

• Specific gravity: 1.930g_n.
• Vapour  pressure: 10 mm @ 693 °C.

Appearance and odour:
Blue green crystals; readily oxidizes in solution

Preparation of iron 2 chloride

Wastes from steel production are made to treat with hydrochloric acid.  we get a hydrated form of Iron 2 chloride. When the hydrochloric acid is not completely consumed, such solutions are named as “spent acid,"
                             Fe + 2 HCl → FeCl₂ + H₂

Laboratory Preparation method:
Iron 2 chloride can be prepared by treating Iron powder with a solution of methanol and concentrated Hydrochloric acid under inert atmosphere. This reaction gives the methanol solvate, under vacuum heating to about 160°C gives anhydrous Iron 2 chloride.
Another laboratory method of synthesis of Iron 2 chloride is the treatment of FeCl₃ with Chlorobenzene

2 FeCl₃ + C₆H₅Cl → 2 FeCl₂ + C₆H₄Cl₂ + HCl
Preparation of Iron 2 chloride in this way shows convenient solubility in tetrahydrofuran, a commonly used solvent for the chemical reactions. In ferrocene, Wilkinson reactions generated Iron 2 chloride by heating FeCl₃ with iron powder. At high temperatures Ferric chloride decomposes to ferrous chloride.

Reactions of Iron 2 chloride

Iron 2 chloride forms complexes with many ligands. Iron 2 chloride when treated with two molar equivalents of [(C₂H₅)₄N] Cl to yield the salt [(C₂H₅)₄N] ₂[FeCl₄]. In the same way, some compounds also prepared are, [MnCl₄]²⁻, [MnBr₄]²⁻, [MnI₄]²⁻, [FeBr₄]²⁻, [CoCl₄]²⁻, [CoBr₄]²⁻, [NiCl₄]²⁻, and [CuCl₄]²⁻ salts.

Applications of Iron 2 chloride

Iron 2 chlorides is widely used in,

1. Preparation of Iron complexes.
2. In waste water treatment
3. Iron 2 chloride is used as a reducing flocculating agent in treatment with chromate containing waste water.  
4. In many of organic synthesis and reaction, Iron 2 chloride is used as a reducing agent.

Organic chemistry in life

Here was once a time when chemists thought "organic" referred only to things that were living, and that life was the result of a spiritual "life force." While there is nothing wrong with viewing life as having a spiritual component, spiritual matters are simply outside the realm of science, and to mix up the two is as silly as using mathematics to explain love (or vice versa). In fact, the "life force" has a name: carbon, the common denominator in all living things. Not everything that has carbon is living, nor are all the areas studied in organic chemistry—the branch of chemistry devoted to the study of carbon and its compounds—always concerned with living things.The element carbon forms a vast number of compounds. 

Over 16 million carbon-containing compounds are known, and about 90% of the new compounds synthesized each year contain carbon. The study of carbon compounds constitutes a separate branch of chemistry known as organic chemistry. This term arose from the eighteenth-century belief that organic compounds could be formed only by living systems. This idea was disproved in 1828 by the German chemist Friedrich Wöhler when he synthesized urea (H2NCONH2), an organic substance found in the urine of mammals, by heating ammonium cyanate (NH4OCN), an inorganic substance. Organic chemistry addresses an array of subjects as vast as the number of possible compounds that can be made by strings of carbon atoms.

Chemistry of Life

Life on earth depends on the chemical element carbon, which is present in every living thing. Carbon is so important, it forms the basis for two branches of chemistry, organic chemistry and biochemistry. The GED will expect you to be familiar with the following terms:

Hydrocarbons - molecules that only contain the elements carbon and hydrogen (e.g., CH4 is a hydrocarbon while CO2  is not)

Organic - refers to the chemistry of living things, all of which contain the element carbon

Organic Chemistry - study of the chemistry of carbon compounds involved in life (so, studying diamond, which is a crystalline form of carbon, isn't included in organic chemistry, but studying how methane is produced is covered by organic chemistry)

Organic Molecules - molecules that have carbon atoms linked together in a straight line (carbon chain) or in a circular ring (carbon ring)

Polymer - hydrocarbons which have chained together

Separation of organic compounds

Introduction

The Separation of a mixture of organic compounds to give the pure components is of the great practical importance in chemistry. Many synthetic reactions react to give mixture of products. It is necessary to have a reasonably clear idea of how the mixture of compounds can be separated out. Almost all the compounds which have the interest of biochemical occurs naturally as components of very complex mixture from which they can be separated out only with considerable difficulty and efficiency.

Separations of organic compounds can be achieved by differences in physical and chemical properties, such as differences in boiling point, melting point etc. or by chemical means, having differences in physical properties which are regulated by chemical reactions.

Problems in Separation of organic compounds

A common problem arises in organic chemistry involves the separation of a mixture of two or three organic compounds into single compound fractions followed by the purification and identification of each organic compound.  To effect the separation of organic compounds, the chemist must make use of the different properties of the components. The phenomena such as differences in solubility, density, acid-base chemistry and reactivity are used to separate a mixture of organic compounds.

Then each component is purified and identified.  For example the carboxylic acid can react with a base such as sodium hydroxide and forms an anion which is water soluble. The neutral doesn’t react and so it remains “neutral”. The possible organic neutral compounds are separated out.

Utility of Separation of organic compounds

It is important to note that single extractions of organic compound for its separation do not necessarily yield complete separations, and that multiple extractions sometimes needed. It includes the extraction the original organic solution two times with aqueous sodium hydroxide solution to remove the acid and water soluble impurities from the organic layers of mixture.

The two aqueous extracts are then combined with each other and set aside as the aqueous sodium hydroxide fraction. The organic compound is further extracted once with distilled water to remove any water soluble impurities.  Once these extractions of organic compound are complete, the organic solution should contain only the "neutral" compound.

Structural representations of organic compounds

Introduction

The structural formula of a chemical compound is a graphical representation of the molecular structure to show that how the atoms are arranged. The chemical bonding inside the molecule is shown, either explicitly or implicitly. There are three common representations which used in publications: text, Lewis type and line-angle formula. Also many other formats are used, as in chemical databases, like SMILES, InChI and CML.

Structural formulas give a representation of the molecular structure. Chemists mostly describe a chemical reaction or synthesis by using structural formulae instead of chemical names, because the structural formulas allow the chemist to observe the molecules and the changes that occur.

Many chemical compounds are present in different isomeric forms, which have different structures but the same overall chemical formula. A structural formula indicates the arrangements of atoms in a mannered way which a chemical formula cannot do.

Text formulas

In early organic chemistry publications, when use of graphics was strictly limited, a text-based system came for describing organic structures in a line of text. Although this system tends to break down with complex cyclic compounds, it remains a easier way to represent simple structures.

CH₃^–CH₂^–OH or CH₃CH₂OH

Lewis structures

Lewis structures are flat graphical formulas which show the atom connectivity, but do not give information about the three-dimensional structure of molecules. This notation is commonly used for small linear molecules. A single line shows a single bond or single electron pair. Two and three lines show double and triple bonds, respectively. Alternatively, dots (•) are used to show single electrons. This is called as Lewis Dot Structure.

Three-dimensional structures

Several methods are present to picturize the three-dimensional arrangement of atoms in a molecule.

Fischer projection

The Fischer projection is commonly used for linear monosaccharides. The vertical backbone is implicit to form a bridge-like structure on the paper plane with the substituents sticking up.

Perspective drawings of cyclic conformations

Perspective drawing is a three-dimensional perspective of a cyclic compound, also shows the structure of the ring, as it is an example a chair conformation.

Newman projection and sawhorse projection

The Newman projection and the sawhorse projection are used for depicting the stereochemistry at two connected carbon atoms.

Skeletal formulas

Skeletal formulas are the standard information for more complex organic molecules. Carbon (C) atoms are represented by the vertices (corners) and termini of line segments which are not marked with an atomic symbol. Each carbon atom is in turn thought to bear enough hydrogen atoms to give the carbon atom four bonds.

Stereochemistry in skeletal formulas

Chiral property in skeletal formulas is denoted by the Natta projection method. Solid or dashed wedged bonds symbolize bonds pointing above-the-plane or below-the-plane of the paper, respectively.

Organic Nomenclature

A member of a large class of chemical compounds containing carbon in their molecules is organic chemical.Compounds such as simple oxides of carbon and cyanides, carbonates, including allotropes of carbon as well are considered inorganic due to some historical reasons.

The science that is concerned with all aspects of organic compounds is termed as organic chemistry and the methodology to prepare these compounds is organic synthesis.

"Organic" is an historical  name, which dates back to the first century. Vitalism was believed by western alchemists for many centuries. Vitalism was the theory which stated that  certain compounds could only be synthesized from their classical elements Earth, Water, Air and Fire by the action of a "life-force" which is possessed only by organisms. According to this theory these "organic" compounds differ fundamentally from the "inorganic" compounds that could be obtained by chemical manipulation of the elements.

There are different ways to classify organic chemicals. Natural and synthetic compounds are major distinction between them. The presence of heteroatoms can classify or subdivide organic chemicals,taking example of organometallic compound in which bonds between carbon and a metal is featured, and compounds in which bonds between carbon and a phosphorus is featured is organophosphorus.

The size of organic compounds distinguish between small molecules and polymers, this is another criteria to classify organic chemicals.

Synthesis of organic compounds from Natural compounds

Those chemicals which are produced by plants or animals are natural compounds. It may be expensive to produced some compounds artificially so they are still taken from natural sources. For examples most sugars, some alkaloids and terpenoids are included in this category, certain nutrients as vitamin B12, and those natural products which are stereoisometrically complicated molecules present in reasonable concentrations in living organisms.

Compounds such as antigens, carbohydrates, enzymes, hormones, lipids and fatty acids, neurotransmitters, nucleic acids, proteins, peptides and amino acids, lectins, vitamins and fats and oils, are of prime importance to biochemistry.

Organic chemicals: Synthetic Compounds

Synthetic compounds are those which are prepared by reaction of other compounds. They may be the compounds already found in plants or animals (semi synthetic compounds), or those which are not found naturally.

A category which includes all plastics (polymers) are organic compounds. An exception that is noticable is silicone, which comes in both category of polymer and a plastic.

Ionic radii table

What is Ionic Radii ?

Ionic radii is related to ions present in ionic substances (crystalline solids). Ions are formed when neutral atom either gain or lose electrons. The effective size of the cation (+ charged) or anion (- charged) is termed as ionic radius. It is defined as the distance between the nucleus and outermost shell of an ion or it is the distance between the nucleus and the point where the nucleus exerts its influence over the electron cloud.

Comparative size of the atoms and the cations in the table

Comparison of the ionic radii with corresponding atomic radii of the cation is always smaller than the atomic radii of the parent atom. The radius of the anion is always larger than the atomic radii of the parent atom.

Comparative size of the atoms and the cations in the table

Atom	Atomic radii (crystal radius)Ao	Corresponding cation	Ionic radii (Ao)
Li	1.52	Li+	0.59
Na	1.86	Na+	0.99
K	2.31	K+	1.33
Mg	1.60	Mg2+	0.65
Ba	2.22	Ba2+	1.35
Al	1.43	AL3+	0.50
Pb	1.75	Pb2+	1.32

Comparison of atoms and their anions in the table

Atom	Atomic radii (crystal radius)Ao	Corresponding cation	Ionic radii (Ao)
F	0.72	F­-	1.36
Cl	0.99	Cl-	1,81
Br	1.14	Br-	1.96
O	0.73	O2-	1.04
S	1.04	S2-	1.84
N	0.75	N3-	1.71
P	1.10	P3-	2.12

The Z/e Ratio and comparison of different radii

In any particular group, the ions either anions or cations increases as we move top to down, this is because the increase in the number of shell as observed in case of the atomic radius. The size of the cation decreases with the increase in the positive charge. And the size of the anion increase as the negative charge on the anion increases.

This can be explained on the basis of Z/e ratio, whenever this ratio increases, the size of the ion decreases.

Na	Na+	Cl	Cl-	Fe2+	Fe3+
Z/e=11/11=1	11/10=1.1	17/17=1	17/18=.95	26/24=1.08	26/23=1.13

Therefore the relation between the ionic radii and the ions would be:

 Na>Na⁺    Cl <Cl^-   Fe²⁺>Fe³⁺

Most reactive metals in the periodic table

Introduction :
A periodic table is an arrangement of all the known elements in vertical groups and horizontal rows so that the elements with similar physical and chemical properties are placed in the same group.In 1912, Moseley proposed the modern periodic law.  The modern periodic law states that the physical and chemical properties of the elements are periodic functions of their atomic numbers.  There are 18 vertical columns and 7 horizontal rows.The Vertical columns present in the periodic table are represented by Groups.  The horizontal rows present in the periodic table are represented by Periods.

The most reactive metals in the periodic table are:

• Lithium( Li)
• Sodium (Na)
• Potassium(K)
• Rubidium(Rb)
• Caesium(Cs)
•  Francium(Fr)

These elements are called Alkali Metals Periodic Table because their oxides and hydroxides dissolve in water to produce strong alkalies.  They are most reactive and highly electropositive elements in the periodic table.  Group first elements of the periodic table are called as alkali metals.  These are very reactive metals we cannot get freely in nature.  There is only one electron in the outer most shell of these metals.  During the formation of ionic bonding with the other elements, these elements ready to lose one electron. 

In comparison to all metals, alkali metals are more ductile, malleable and good conductors of heat and electricity.  The most reactive elements in this group are Cesium and francium.  If alkali metals are exposed to water they can explode.

Colour of alkali metals during flame test:

Metal ion	Flame colour
Lithium	Crimson red
Sodium	Golden yellow
Potassium	Lilac (pale violet)
Rubidium and caesium	Violet

Properties of Most reactive metals in the periodic table (alkali metals):

1. Alkali metals are the light metals.  Their density is low because of larger atomic volumes.
2. Alkali metals have low ionization energies because the last electron is present in the outermost s-orbital and the removal of electron is easy.
3. Due to low ionization energy , alkali metals are highly electropositive.
4. The metallic character of alkali metals increases from lithium to caesium due to low ionization energy.
5. Alkali metals are powerful reducing agents because they have very low reduction potentials.
6. Alkali metals are exposed to air, they tarnish rapidly due to the formation of oxides on the surface.  Hence they are most reactive metals kept under kerosene or paraffin oil and protected from the action of air.

Standard measurement table

Introduction:
In the metric system of measurement, designations of multiples and sub-divisions of any unit may be deduced by combining with the name of the unit the prefixes like deka to, and kilo meaning, respectively, 10, 100, and 1000, and deci, centi, and milli, meaning, respectively, one-tenth, one-hundredth, and one-thousandth.

In scientific usage, it becomes convenient to measure multiples larger than 1000 and subdivisions smaller than one-thousandth. Therefore, the following prefixes have been introduced and these are recognized worlwide:

yotta,   (Y),      meaning 10²⁴            deci,    (d),        meaning 10^-1
zetta,   (Z),       meaning 10²¹            centi,   (c),        meaning 10^-2
exa,     (E),       meaning 10¹⁸            milli,    (m),       meaning 10^-3
peta,   (P),       meaning 10¹⁵            micro, (u),         meaning 10^-6
tera,    (T),       meaning 10¹²            nano,   (n),        meaning 10^-9
giga,   (G),       meaning 10⁹             pico,    (p),         meaning 10^-12
mega, (M),      meaning 10⁶             femto, (f),          meaning 10^-15
kilo,     (k),      meaning 10³             atto,     (a),        meaning 10^-18
hecto,  (h),       meaning 10²             zepto,  (z),        meaning 10^-21
deka,  (da),      meaning 10¹             yocto,  (y),        meaning 10^-24

Units of Length

10 millimeters (mm)  = 1 centimeter (cm)
10 centimeters          = 1 decimeter (dm) = 100 millimeters
10 decimeters           = 1 meter (m)
10 meters                  = 1 dekameter (dam)
10 dekameters          = 1 hectometer (hm)
10 hectometers         = 1 kilometer (km)

Units of Liquid Volume

10 milliliters (mL)       = 1 centiliter (cL)
10 centiliters              = 1 deciliter (dL)
10 deciliters               = 1 liter
10 liters                     = 1 dekaliter (daL)
10 dekaliters             = 1 hectoliter (hL)
10 hectoliters             = 1 kiloliter (kL)

Units of Area

100 square millimeters (mm²)         = 1 square centimeter (cm²)
100 square centimeters                  = 1 square decimeter (dm²)
100 square decimeters                   = 1 square meter (m²)
100 square meters                          = 1 square dekameter (dam²) = 1 are
100 square dekameters                  = 1 square hectometer (hm²) = 1 hectare (ha)
100 square hectometers                 = 1 square kilometer (km²)

Units of Mass

10 milligrams (mg)    = 1 centigram (cg)
10 centigrams           = 1 decigram (dg) = 100 milligrams
10 decigrams            = 1 gram (g)
10 grams                   = 1 dekagram (dag)
10 dekagrams           = 1 hectogram (hg)
10 hectograms          = 1 kilogram (kg)
1000 kilograms         = 1 megagram (Mg) or 1 metric ton(t)

kelvin scale definition

Introduction :
The Kelvin Scale or the absolute scale of temperature – Lord Kelvin devised a scale of temperature which is independent of the thermal property of the working substance. This scale is called Kelvin or absolute scale of temperature. The zero of this scale is the temperature at which the molecular motion ceases and average kinetic energy of molecules becomes zero. This temperature is called absolute zero. It is the lowest attainable temperature. No temperature can be less than this temperature. The temperature on this scale is represented by T and the unit is K i.e. Kelvin.

Relation between Celsius and Kelvin Scale

The size of 1 degree on Kelvin scale is the same as the size of 1 degree on Celsius scae i.e., the difference or change in temperature is the same on both the scales. The ice point 0 degree on the absolute scale is 273K and the steam point 100 degree Celsius is 373K. The absolute zero on this scale is thus corresponds to -273 degree Celsius.

Any temperature t degrees on the Celsius scale is equal to (273 + t) on the Kelvin scale.
And, since 100 Centigrade degrees (ice point is marked as 0 degrees and the steam point is marked as 100 degrees).= 180 Fahrenheit degrees

The relation between Fahrenheit and Kelvin scale is given by the formula,
Kelvin = [(°F-32) / (1.8)] + 273.15

Advantages of using kelvin scale

• If we keep the volume of a sample of gas constant, the pressure of the gas goes up in proportion to the Kelvin temperature. This is automatically holds good for an ideal gas; this is quite fortunate enough that many gases have almost  depict identical behavior, except at very low temperatures. 

•  For standard thermometers, we can change from ordinary mercury thermometers, which are convenient, to a gas thermometer. 

Thus a Kelvin scale is much more beneficial as compared to a Fahrenheit or Celsius scale

Discovery of Atom

Introduction 
The term atom has its origin from the Greek word ‘átomos’ which means indivisible or, uncuttable, something that cannot be divided further. Indian and Greek philosophers first proposed the concept of an atom as an indivisible component of matter. Chemists provided a physical basis for this idea in the 17th and 18th centuries, by showing that certain substances could not be further broken down by chemical methods.



      Picture of an atom 1

Discovery of atom

Way back in 300-400B C, Democritus and Epicurus the greatest Greek philosophers proposed that there were indivisible atoms having a size, weight and shape. They stated that everything in the universe was made of those indivisible atoms including human's body and soul.  They also suggested that in empty space atoms could move uniformly and they could also vibrate at random and turn.

In 1803 John Dalton, English instructor and philosopher, used this concept of atoms and explained that elements always react in ratios of small whole numbers. He also explained that certain gases dissolve better in water than others. He theorized that every element consists of atoms of a single type, and that these atoms can join together to form chemical compounds. Dalton is regarded the originator of modern atomic theory.

The atom is the simplest unit of matter which consists of a nucleus at the center and is surrounded by negatively charged particles called electrons. The nucleus consists of protons that are positively charged and neutrons that are neutral in charge. The electrons are bound to the nucleus with the electromagnetic force. Two or more atoms together form a molecule. If the atom has equal number of protons and electrons, it is called electrically neutral, however if the protons are more, the atom is called as positively charged and if electrons are more, it is called negatively charged.

However, during the end of 19th and early 20th centuries, physicists have discovered subatomic components and structure inside the atom, and thereby proved that the 'atom' was indeed divisible. Scientists have used many principles of quantum mechanics in order to explain the model of the atom.

Conclusion to the discovery of atom

The discovery of atom was the major milestone in science. This enabled the formulation of periodic table and brought major advancement in science.

Basic structure of an atom

Introduction

The atom is the building block of the substance; each and every thing is made up of atom. In earlier concept it was thought that atom was indivisible, with the advancement in the technology and after a lot of results and experiments it is now proved that atom can further be divided in to more fundamental particle. Ruther ford on the basis of his experiment of scattering of alpha particle through the gold foil drew following conclusions.

Basic structure of an atom

Most of the part of the atom is hollow, approximately all the mass of the atom is concentrated to a very small region called the nucleus compare to the atom the nucleus is very small, the radius of the atom is of the order of 10^-10 meter while the radius of the nucleus ids of the order of 10^-15 meter, therefore the nucleus is about 10^5th part of the atom.

Protons and the neutrons reside in the nucleus while electrons revolve round the nucleus in the different orbits. Bohr’s gave the idea of the stationary orbit, according to him the electrons move round the nucleus in the stationary orbit, the stationary orbits are those in which the angular momentum of the moving electrons is conserved , so it does not lose its energy, these stationary orbits are called energy levels , and are represented by the capital letters, K,L,M,N etc, according to 

Bohr’s scheme the maximum number of electron that can occupy a hell is given by the formula 2n² , where n is the number of shell, using this formula it is clear that the number of an electron that can be accommodated in 1, 2,3and4 shell is  2,8,18 and 32  respectively,

The shell is further divided in to sub shells and the sub shells are composed of the orbitals , there are different type of orbitals like s,p,d,,f,g etc, according to quantum mechanical model the electrons have dual nature they have both particle as well as the wave nature. They are like stationary waves’ round the atoms, and the orbital s are nothing but wave functions.

There are more fundamental particles which are discovered apart from the neutrons, protons and electrons , these are different types of mesons, neutrino quark etc.the scientific advancement is a continuous process and scientist are in the constant effort to find the ultimate particles called the god particles which are the building block of all kind of matter.

Argon atom

Argon is basically a Greek word, argos meaning lazy. It was suspected in 1785 that it was present in air by Henry Cavendish. Later it was discovered by Lord Rayleigh and Sir William Ramsay in 1894.

Introduction :
The Argon atom is the chemical element which is present in the eighteenth group of the periodic table. Argon atom symbol is Ar. It is having an atomic number 18 and atomic weight 39.948amu it’s equal to 40 amu. It belongs to eighteenth group, (viii A) period and it is a p-block element. It has 18 electrons and 18 protons and has 22 neutrons. Density of Argon atom is 1.784 kg/m^3. Argon atom belongs to noble gas series. It belongs to p–block is predicted by its electronic configuration. The electronic configuration is based on atomic number of an atom, so the electronic configuration of Argon atom is 1s² 2s² 2p⁶ o [Ne] 3s² 3p⁶, here the outermost electron present in the p-orbital so it belongs to p-block. It has cubic face centered crystal structure. It is diamagnetic in nature. It is the third noble gas.

Electron Shell model of Argon atom

It has 3 main isotopes; they are Ar-40, Ar-36, and Ar-38. Ar -39 is made by cosmic ray activity. Ar-40 is produced by neutron capture method from K -39 and also by alpha emission by calcium and Ar-37 is produced by the decay of Ca -40.

Physical properties of argon atom:

1. It is a non-metallic, colorless and odorless  gas at room temperature i.e. at 298K.
2. Its melting point and boiling point are 83.8K and 87.3K respectively.
3. It occupies about 1% of Earth’s atmosphere.
4. It is chemically inert so it does not react with any element or a molecule.
5. It is stored at high pressures.

Applications of argon atom:

Argon atom is used

1.     In  lighting due to its high stability AND it will not react with the filament in a bulb even under high temperatures

2.     Due to its inertness, it is used as inert gas shield in case of welding.

3.      In the manufacture of titanium as a non- reactive blanket and many more.

Aluminium atom

Introduction:
Aluminium atom is a silvery white member which belongs to the boron group element.  It has an atomic number 13 and Al is its symbol. Aluminium is the third most abundant metal in the Earth's crust, after oxygen and silicon. It makes up about 8% by weight of the Earth's solid surface. Aluminium is reactive chemically to occur in nature as a free metal. Instead, it is found combined in over 270 different other minerals. Bauxite ore is the chief source of aluminium.

One of the remarkable properties of Aluminium atom is for its low density metal and for its ability to resist corrosion due to the phenomenon named as passivation.

The property of Aluminium metal depends on Aluminium atoms present in it. Aluminium is a soft, durable, lightweight, ductile and malleable metal of the 3^rd period. Its appearance ranges from silvery to dull gray, depending on the surface roughness. Aluminium is nonmagnetic metal. It is also insoluble in alcohol, in certain forms though it can be soluble in water. 7–11 MPa is the yield strength of pure aluminium, while aluminium alloys yield strengths ranging from 200 MPa to 600 MPa. Aluminium atom has about one-third the density and stiffness of steel.

Face-centered cubic (fcc) structure is the atomic arrangement of Aluminium atoms.  Aluminium metal has a stacking -fault energy of approximately 200 mJ/m².

Characteristics of aluminium atom

Aluminium is a metal which is present in 13th (lllA) group and 3^rd period of the periodic table. It has the electronic configuration 1s²2s²2p⁶3s²3p. Aluminium has the Oxidation state of +1,+2, and +3.

The outer three electrons occupy three s²p hybrid orbitals that point in orthogonal directions. These electrons easily form covalent bonds, as in anhydrous AlCl₃. This compound easily sublimates, showing that it is not ionic, and is partially hydrolyzed by H₂O to release HCl gas. It cannot be formed by heating the hydrated form to drive off H₂O.

3s²3p² 3p  is the spectroscopic ground state. The resonance line is at 396.15 nm of Aluminium atom, that’s why aluminium atom is not excited in the flame and gives it no color. When the atom is excited, most of the lines are in the red or infrared in nature. Aluminium is in column IIIA of the modern periodic table, which includes boron, aluminium, gallium, indium and thallium. Aluminium atom is the only common element in the group, and is considerably different from the others in physical and chemical properties.

Aluminium is the most widely used non-ferrous metal among the metals. Relatively pure aluminium is encountered only when corrosion resistance and workability is more important than strength or hardness. A thin layer of aluminium can be deposited onto a flat surface by physical vapour deposition or chemical vapour deposition or other chemical means to form optical coatings and mirrors on the surfaces.

Applications of aluminium atom

Other uses of Aluminium Atom: 

• Transportation: Here Aluminium is used as body parts such as automobiles, aircrafts, trucks, railway cars, marine vessels, bicycles etc. as sheet, castings etc.,
• Packaging of Food and other things are made by Aluminium foil.
• Construction of building materials. (Windows, doors, siding, building wire, equipments etc.)
• A wide range of household items, from cooking utensils to baseball bats, watches etc., are made from Aluminium atom.
• Street lighting poles, sailing ship mats, walking poles, roof cover etc., are made by strong Aluminium Rods.
• Outer shells of consumer electronics, also cases for equipment e.g. photographic equipment etc., are made from Aluminium.