Given below are some elements of the Modern Periodic Table:
`""_(4)Be, ""_(26)Fe.""_(14)Si, ""_(19)K ""_(20)Ca`
i) Select the element that has one electron in the outermost shell and write its electronic configuration.
ii) Select two elements that belong to the same group. Give reason.
iii) Select two elements that belong to the same period. Which one of the two has a bigger atomic size?

Explanation

The electronic configurations are: `Be (4) to 2,2, Fe (26) to` is a transition metal, `Si (14) to 2, 8, 4, K (19) to 2,8,8, I, and Ca (20) to 2, 8, 8, 2. `
i] K has one electron in its outermost shell and hence it belongs to group 1. Its electronic configuration is 2, 8, 8,1.
ii] From the electronic configuration, Be and Ca have the same number of valence electrons and hence belong to the same group. iii] Potassium (K) and calcium (Ca) belong to the same period since they have 4 electron shells each. K has bigger atomic size.