1. Group-6

3.  An ion is an atom or group of atoms that have a net electrical charge. An ion is formed when electrons or protons are gained or lost by an atom.  There are two types of ions: Cations and Anions.

4.  Cations :A positively charged ion is known as cations. A cation is formed by the loss of one or more electrons by an atom.  Anions: A negatively charged ion is known as Anion. An anion is formed by the gain of one or more electrons by an atom.

5.  The compounds which are made up of ions are known as ionic compounds.  In an ionic compound, the positively charged ions and negatively charged ions are held together by the strong electrostatic forces of attraction.  The forces which hold the ions together in an ionic compound are known as ionic bonds and electrovalent bonds.

6.  Since an ionic compound consists of an equal number of positive ions and negative ions, so overall charge of an ionic compound is zero.  Example: Sodium chloride- NaCl Potassium Chloride- KCl += Na Cl NaCl

7.  During the formation of NaCl, one electron is transferred from a sodium atom to a chlorine atom

8. In general, a cation will react with an anion to acquire a full valence shell

9. NameFormulaIons present 1. Sodium ChlorideNaClNa + and Cl - 2.Potassiun ChlorideKClK + and Cl - 3.Ammonium ChlorideNH4ClNH 4 + and Cl - 4.Magnesium ChlorideMgCl2Mg 2+ and Cl - 5. Calcium ChlorideCaCl2Ca 2+ and Cl - 6. Magnesium OxideMgOMg 2+ and O 2 - 7. Calcium OxideCaOCa 2+ and O 2 - 8.Aluminium OxideAl2O3Al 3+ and O 2- 9.Sodium HydroxideNaOHNa + and OH- 10.Copper SulphateCuSO4Cu 2+ and SO 4 2- 11.Calcium NitrateCa(NO3)2Ca 2+ and NO 3 - Note: Ionic compounds are made up of a metal and a non-metal(except ammonium chloride which is made up of only non-metals.

10. The attraction between the cation and the anion is known as an ionic bond. This bond is what holds the ionic compound together.

11.  The simplest combination of ions that produces an electrically neutral unit, is called a ‘Formula Unit’ of ionic compound.  The ‘formula unit’ of an ionic compound can be thought of as the smallest unit that compound, it is the equivalent of a ‘molecule’ of the compound.

12.  Formula mass is the sum of the atomic masses of the atoms (or ions) represented by its formula.  In order to calculate the formula mass of an ionic compound, we should know the formula of the ionic compound as well as the atomic masses of all the atoms (or ions) present in the formula.

13.  To calculate the formula mass of potassium carbonate (K 2 CO 3 ):  Atomic masses: K= 39u ; C= 12u ; 0= 16u Formula mass of K 2 CO 3 = Mass of 2 K atoms+ Mass of one C atom+ Mass of 3 O atoms =2*39+12+3*16 =78+12+48 =138u Thus, the formula mass of potassium carbonate is 138u.

14.  At room temperature, most are hard, brittle solids that can be crushed.

15.  Ionic compounds form crystals that have an alternating arrangement of positively charged ions and negatively charged ions, so that when they break their edges are well-defined.

16. In an ionic crystal, every ion is attracted to every other ion in the crystal. As a result, ionic crystals have very high melting points ex.) NaCl melts at 800 o C In an ionic crystal, every ion is attracted to every other ion in the crystal. As a result, ionic crystals have very high melting points ex.) NaCl melts at 800 o C

17.  When an ionic compound dissolves in water, the crystal structure breaks down and the ions become free to move.

18.  Solutions of ionic compounds can conduct electricity.