Atoms

Atoms are composed by three subatomic particles: protons, neutrons and electrons.

In general the structure of atom consists of two parts: a nucleus and electrons that surround the
nucleus. Nucleus lies at the center of the atom and are composed of protons and neutrons. The
number of protons in the nucleus of the atom determines what type of element the atom is. For example, hydrogen, the smallest atom, has only one proton in its nucleus and
oxygen has 8 protons, gold has 79 and uranium, the heaviest atom found naturally, has 92
protons. Nucleus has another constituent. It is called neutron. The presence or the number of
neutrons in a nucleus does not affect the element type. Except for the lightest hydrogen atoms,
all other atoms have one or more neutrons in them.

What then are the differences between proton, neutron and electron? They have different
electric charges. Protons are positively charged, electrons are negatively charged and the
neutrons have no charge. Electron has been translated by some as the “negative particle”
because of its negative charge. The three particles have different masses. Electrons have much
smaller masses. In fact, it’s mass is approximately 1/2000th times that of proton and neutron. In
terms of composition of the particles, protons and neutrons are composed of quarks. But so far
scientists have not discovered any constituent particles for electrons.