Atomic numbers of the following elements are given below:

A = 8; B = 7; C = 17; D = 11; E = 20

1. State which of the above is a divalent metal.
2. State which of the above is a non-metal.
3. State the type of bonding between two atoms of 'A'.
4. State the type of bonding between 'D' & 'C'.
5. State the number of covalent bonds formed in a molecule of 'B₂'.

1. E is a divalent metal as it has 2 electrons in the valence shell [electronic configuration 2,8,8,2] and it tends to lose two electrons in order to gain a stable octet configuration.
2. C is a non-metal as it's electronic configuration is 2,8,7 and it tends to gain one electron to attain a stable state.
3. Double covalent bond as the electronic configuration of A is 2,6 [non-metal], both A atoms will try to gain 2 electrons to attain a stable octet and none of the combining atoms are in a position to donate. Hence, they form the bond by sharing of 2 valence electrons and form a double covalent bond.
4. Electrovalent bond as the elect. configuration of D = [2,8,1] and C = [2,8,7], hence, D donates one electron and becomes a cation whereas C takes up one electron and becomes a anion. The attractive force between a cation and anion results in formation of an electrovalent bond.
5. Triple covalent bond as the electronic configuration of B is [2,5], hence, B needs 3 electrons to attain a stable octet configuration and hence forms a triple covalent bond.