Knowledge Booster

• General Characteristics of ionic Compounds : (i) Physical State: They generally exist as crystalline solids, known as crystal lattice. Ionic compounds do not exist as single molecules like other gaseous molecules e.g., H 2  , N 2  , 0 2  , Cl 2  etc. (ii) Melting and boiling points: Since ionic compounds contain high interionic force between them, they generally have high melting and boiling points. (iii) Solubility: They are soluble in polar solvents such as water but do not dissolve in organic solvents like benzene, CCl4etc. (iv) Electrical conductivity: In solid state they are poor conductors of electricity but in molten state or when dissolved in water, they conduct electricity. (v) Ionic reactions: Ionic compounds produce ions in the solution which gives very fast reaction with oppositely charged ions. For example, •  Covalent Bond—Lewis-Langmuir Concept : When the bond is formed between two or more atoms by mutual contribution and shar...

Modes of Chemical Combination — By the transfer of electrons: The chemical bond which formed by the complete transfer of one or more electrons from one atom to another is termed as electrovalent bond or ionic bond. — By sharing of electrons: The bond which is formed by the equal sharing of electrons between one or two atoms is called covalent bond. In these bonds electrons are contributed by both. Co-ordinate bond: When the electrons are contributed by one atom and shared by both, the bond is formed and it is known as dative bond or co-ordinate bond. Ionic or Electrovalent Bond Ionic or Electrovalent bond is formed by the complete transfer of electrons from one atom to another. Generally, it is formed between metals and non-metals. We can say that it is the electrostatic force of attraction which holds the oppositely charged ions together. The compounds which is formed by ionic or electrovalent bond is known as electrovalent compounds. For Example, , (i) NaCl is an electrovalent compou...

Chemical Bond The force that holds different atoms in a molecule is called chemical bond. Octet Rule Atoms of different elements take part in chemical combination in order to complete their octet or to attain the noble gas configuration. Valence Electrons It is the outermost shell electron which takes part in chemical combination. Facts Stated by Kossel in Relation to Chemical Bonding •  In the periodic table, the highly electronegative halogens and the highly electro-positive alkali metals are separated by noble gases. • Formation of an anion and cation by the halogens and alkali metals are formed by gain of electron and loss of electron respectively. •  Both the negative and positive ions acquire the noble gas configuration.  The negative and positive ions are stabilized by electrostatic attraction Example,