Question

An element X belong to group 1 and 3 periods.(i)Give its electrone confugation.(ii) formula when it combine with oxygen. (iii) state its nature.

Answer 1

Name of element. Sodium
Electronic configuration. 2,8,1
Na + O2 gives out Na2O
Nature is Metal. alkaline earth metal

Answer 2

An element from group 1 and 3rd period means the valence shell should be $3 \mathrm{s}^{1}$.  

a)   $\bold{1 \mathrm{s}^{2}, 2 \mathrm{s}^{2}, 2 \mathrm{p}^{6}, 3 \mathrm{s}^{1}}$

b)   If the element is M, then it will form $\mathrm{M}^{+}$ ion as it has one valence e- so it will form $\mathrm{M}_{2} \mathrm{O}$ type of oxide.

c)   It must be metallic in nature as it has 1 electron in its valence shell. It is also part of group 1 so it is alkali metal.