What is Plasma?

A plasma (or, more properly, an electromagnetic plasma) is a phase of matter that has enough energy for the electrons to separated from the nucleus. It consists of independently moving electrons and nuclei, and thus has some rather interesting properties, such as very good magnetic shielding. It can be found in places such as the center of the sun, and also, in small quantities, surrounding a lightening bolt. 

Many people consider solid, liquid, gas and plasma to be the only four phases of matter. This is not true, as there exist many others, but they are generally more exotic with names like hadron gas or Bose-Einstein Condensate.

How did atom obtain its name?

The word is derived from the Greek word "atomos", meaning indivisible. The concept of the atom originated round 440 BC. In Greek, the prefix "a" means "not" and the word "tomos" means cut. Word "atom" therefore comes from "atomos", a Greek word meaning uncuttable. 

In 1803, John Dalton formulated the "atomic theory" of matter based on experiments that quantified the weights of elements formed when compounds were broken down. Based on experimental evidence, Dalton proposed that atoms really do exist as fundamental units of all elements. 

Twentieth century physics was able to probe atoms and prove that they are not, in fact, indivisible. But the name stuck, and still has meaning in that atoms are the smallest, indivisible part of any element. If you do divide them into smaller pieces of protons, neutrons and electrons, you no longer have the original element.