The following diagram shows a part of the periodic table containing first three periods in which five elements have been represented by the letters a, b, c, d and e (which are not their chemical symbols):
1 18 a 2 13 14 15 16 17 b c d e
(i) Select the letter which represents an alkali metal.
(ii) Select the letter which represents a nobles gas.
(iii) Select the letter which represents a halogen.
(iv) What type of bond is formed between a and e?
(v) What type of bond is formed between d and e?
(i) The letter 'd' represents an alkali metal. This is because group 1 elements of the periodic table, except hydrogen, are all alkali metals having 1 valence electron.
(ii) The letter 'c' represents a noble gas. All the group 18 elements are noble gases or inert gases whose valence shells are completely filled with electrons.
(iii) The letter 'e' represents a halogen. Group 17 elements are known as halogens and they have 7 valence electrons.
(iv) A covalent bond is formed between 'a' and 'e'. 'a', the top most element represents hydrogen which is the only non-metal in group 1. Therefore, when a non-metal 'a' forms a compound with another non-metal 'e', sharing of electrons takes place resulting in the formation of a covalent bond.
(v) An ionic bond is formed between 'd' and 'e'. When a metal reacts with a non-metal, a transfer of electrons takes place from the metal to the non-metal and results in the formation of an ionic bond.