Atoms and Molecules
What is an Atom?
Matter can be described as any object that occupies space and has weight and mass. It is always found in one of three states- solid, liquid or gas, but no matter which state it is in, matter is made up of microscopic particles called atoms. An atom is a particle that is the most basic unit of matter. Any substance, whether solid, liquid or gas, is made up of millions of these tiny particles.
The origin of the word ‘Atom’
The word atom comes from the Greek word ‘atomos’ meaning indivisible.
The theory that matter is made up of these tiny particles was put forth by ancient Indian and Greek scientists. However, this theory could not be proven, because of the lack of technology. These miniscule particles are so tiny that they can only be observed with a very powerful instrument called a ‘scanning tunneling microscope.’ With its help scientists were able observe and record the nature of this tiny particle.
Structure of the Atom
The structure of an atom very closely resembles that of an egg. It has a nucleus in the middle, like the yolk of an egg. This part is made up of positively charged protons and neutrally charged neutrons. Around the nucleus are negatively charged electrons like the white of an egg, which rotate around the nucleus in fixed orbits.
What is an Atomic Number?
The number of protons in an atom is known as the atomic number. Therefore if an atom has the atomic number 8, it means that there are 8 protons in the nucleus and that the atom is of the element Oxygen. You can also safely say that all oxygen atoms will have 8 protons.
What is a Molecule?
When two or more atoms combine they give rise to a molecule. A molecule can be made up of many atoms of the same element, as in the case of 2 oxygen atoms combining to form O2, or a combination of atoms of different elements; where 2 hydrogen atoms combine with one oxygen atom to form H2O (water). There are 112 elements known to man, so can you imagine the different permutations and combinations of molecules that can exist freely in nature or be synthesized in a laboratory?
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