The document provides information about common elements, atoms, molecules, and ions. It includes tables that list element symbols and atomic masses, common ions and their symbols, examples of ionic compounds and their ratios, and the valencies of different ions. The tables provide essential data about common elements, ions, and how they combine to form ionic compounds.

1. Atoms and Molecules
Modern Symbols of Some Common Element
Element Symbol Element Symbol
Aluminium Al Iron (Latin-Ferrum) Fe
Argon Ar Lead (Latin-Plumbum) Pb
Calcium Ca Magnesium Mg
Carbon C Nitrogen N
Chlorine Cl Oxygen O
Copper (Latin-Cuprum) Cu Potassium (Latin-Kalium) K
Fluorine F Silicon Si
Gold (Latin-Aurum) Au Silver (Latin-Argentum) Ag
Hydrogen H Sodium (Latin-Natrium) Na
Iodine I Zinc Zn

2. Atomic Masses of Some Common Elements
u – Unified atomic mass unit
Atomic mass unit mass of a C-12 atom
1u mass of a C-12 atom
Element Atomic mass Element Atomic mass
(u) (u)
Hydrogen 1 Potassium 39
Helium 4 Calcium 40
Carbon 12 Argon 40
Nitrogen 14 Iron 56
Oxygen 16 Copper 63.5
Fluorine 19 Zinc 65
Neon 20 Bromine 80
Sodium 23 Silver 108
Magnesium 24 Gold 197
Chlorine 35.5 Sulphur 32

3. The name of some common ions with their symbols is given below.
Cation Symbol Atomicity Anion Symbol Atomicity
Aluminium Al3+ Monoatomic Bromide Br– Monoatomic
Ammonium Polyatomic Carbonate Tetra-atomic
Calcium Ca2+ Monoatomic Chloride Cl– Monoatomic
Cuprous ion Cu+ Monoatomic Fluoride F– Monoatomic
Cupric ion Cu2+ Monoatomic Hydride H– Monoatomic
Hydrogen H+ Monoatomic Hydroxide OH– Diatomic
Ferric ion Fe3+ Monoatomic Iodide I– Monoatomic
Magnesium Mg2+ Monoatomic Nitrate Tetra-atomic
Nickel Ni2+ Monoatomic Nitride N3– Monoatomic
Potassium K+ Monoatomic Nitrite Tetra-atomic
Silver Ag+ Monoatomic Oxide O2– Monoatomic
Sodium Na+ Monoatomic Phosphate Polyatomic
Zinc Zn2+ Monoatomic Sulphate Polyatomic
Hydrogen
carbonate Polyatomic Sulphite Tetra-atomic
The table given below illustrates some examples of ionic compounds.
Ionic Compound Combining Ratio by Ratio by number of
Elements mass ions
Calcium oxide Calcium, oxygen 5:2 1:1

4. Magnesium Magnesium, chlorine 24:71 1:2
chloride
Aluminium, sulphur 27:32 2:3
Aluminium
sulphide
The valencies of some common ions are given in the following table.
Name of ion Symbol Valency Name of ion Symbol Valency
Aluminium Al3+ 3 Sulphite 2
Ammonium 1 Bromide Br− 1
Calcium Ca2+ 2 Carbonate 2
Copper(II) Cu2+ 2 Chloride Cl− 1
Hydrogen H+ 1 Hydride H−
Iron(II) Fe2+ 2 Hydrogen 1
carbonate
Iron(III) Fe3+ 3 Hydroxide OH− 1
Magnesium Mg2+ 2 Nitrate 1
Nickel Ni2+ 2 Nitrite 1
Potassium K+ 1 Oxide O2− 2
Silver Ag+ 1 Phosphate 3
Sodium Na+ 1 Sulphate 2
Zinc Zn2+ 2 Sulphide S2− 2