Which one has the largest size?

1. Br
2. I
3. I^-
4. Cl

The metals of group 2 from top to bottom are Be, Mg, Ca, Sr, and Ba

(i) Which one of these elements will form ions most readily and why ?

(ii) State the common feature in their electronic configuration.

Name the element which has :

(i) Two shells, both of which are completely filled with electrons ?

(ii) The electronic configuration 2, 8, 3 ?

(iii) A total of three shells with five electrons in its valence shell ?

(iv) A total of four shells with two electrons in its valence shell ?

(v) Twice as many electrons in its second shell as in its first shell ?

An element Barium has atomic number 56. Look up its position in the Periodic Table and answer the following questions.

(i) Is it a metal or a non-metal ?

(ii) Is it more or less reactive than calcium ?

(iii) What is its valency ?

(iv) What will be the formula of its phosphate ?

(v) Is it larger or smaller than caesium (Cs) in size ?