Atomic Structure and Chemical Bonding — Question 22
Back to all questions(a) Mass number (A) — The mass number of an atom is equal to the total number of nucleons (i.e., the sum of the number of protons and the number of neutrons ) in it's nucleus. It is denoted by A.
A = number of protons + number of neutrons
Mass number however is a whole number approximation of the atomic mass calculated in atomic mass units.
(b) Ion — An ion is a charged particle which is formed due to the gain or loss of one or more electrons by an atom.
For example, a sodium ion (Na+) is formed when a sodium atom loses one electron and Chlorine ion (Cl-) ion is formed when a chlorine atom gains an electron.
(c) Cation — A metallic atom, which loses electron(s), becomes a positively charged ion and is known as a cation.
(d) Anion — A non-metallic atom, which gains electron(s) becomes a negatively charged ion and is known as an anion.
(e) Element — An element is a pure substance that can neither be formed from, nor decomposed into simple substances by ordinary physical or chemical methods.
(f) Orbit — The imaginary circular path around the nucleus of an atom, in which the electrons revolve.