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
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.
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.
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