What is the common feature of the electronic configuration of the elements at the end of Period 2 and Period 3 ?

If an element is in Group 17, it is likely to be …………… [metallic/non-metallic] in character, while with one electron in its outermost energy level (shell), then it is likely to be …………… [metallic/non-metallic].

Complete the following sentences choosing the correct word or words from those given in brackets at the end of each sentence:

(i) The properties of the elements are a periodic function of their …………… (atomic number, mass number, relative atomic mass).

(ii) Moving across a …………… of the Periodic Table the elements show increasing …………… character (group, period, metallic, non-metallic).

(iii) The elements at the bottom of a group would be expected to show …………… metallic character than the element at the top (less, more).

(iv) The similarities in the properties of a group of elements are because they have the same …………… (electronic configuration, number of outer electrons, atomic numbers)

Give reasons for the following:

(i) The size of a Cl^- ion is greater than the size of a Cl atom.

(ii) Argon atom is bigger than chlorine atom.

(iii) Chlorine is less reactive than fluorine.

(iv) Inert gases do not form ion.