. Which element of period 3 of the modern periodic table
(i) is the most reactive non:-metal?
(ii) is the most reactive metal?
(iii) forms ion with -2 charge?
(iv) forms ion with +2 charge?
Ans. (a) Mendeleev was guided by two factors:
(i) increasing atomic masses.
(ii) grouping together of element having similar properties.
(b) (i) Cl is the most reactive non-metal
(i) An element having two shells completely filled with electrons.
(ii) Two elements belonging to the same group of the periodic table.
(ii) Na is the most reactive metal.
(iii) S forms -2 charged ion.
(iv ) Mg forms +2 charged ion.