What's inside an Atom?

In the early 1900’s, the atom was considered the ultimate, indestructible unit of matter. They believed, atoms of the then known elements, such as oxygen, nitrogen, hydrogen and others, could not be broken down into anything simpler. But later, certain experiments like ionic dissociation and the cathode ray tube, indicated the existence of subatomic particles. These and other experiments lead to the knowledge of the proton, electron and neutron as the basic subatomic particles.

Proton: charge = +1, mass = 1.67 x 10^-24 kg

Electron: charge = -1, mass = 9.11 x 10^-27 kg

Neutron: charge = 0, mass = 1.67 x 10^-24 kg

Physicists thus have discovered that atoms are not solid and that electrons rotate around the nucleus and complex orbits. But the understanding of atoms stopped with the electrons, protons and neutrons? The answer is No. 

Modern physics examines particles at the sub-atomic level. Some of the smallest particles are called Quarks. Quark Theory has been around since the mid-nineteen sixties. But a Quark has never been isolated. No one has ever seen a Quark. So you might ask how do scientists know they exist? The answer comes from data collected at high-energy particle accelerators.  Particles are accelerated to nearly the speed of light around the long distant underground tract and smashed together. By studying the patterns made by the new particles that are created in the collisions, scientists are able to determine the properties of the particles and their interactions. The tests have been repeated and the results have been duplicated with enough experiments to convince us that quirks are real and just as fundamental today, as the familiar electron, proton and neutron, were once thought to be. Quarks come in three paired types, that physicists call flavours. They are,

Up and Down

Charm and Strange 

Top and Bottom

Up and down were named based on components of their spin. Strange quarks were given the name, strange because they were observed in particle decays that had slightly longer lifetimes than they should have done. The charm quark was given the name because of it's fascination. The way that it fascinated the physicists at the time. Bottom and Top quarks were chosen by a famous physicist named Haim Harari. He chose the names because they were the logical counterparts of the up and down quark. 

These Quarks are bind together with the help of Gluons. Gluons are hypothetical massless subatomic particle, believed to transmit the force binding the quarks together in a hadron. Gluons mediate the strong force. They have no mass and no electric charge.