Question

The following questions refer to the Periodic Table.
(a) (i) Name the first and last element in period 2.
(ii) What happens to the atomic size of elements moving from top to bottom of a group?
(iii) Which of the elements has the greatest electron affinity among the halogens?
(iv) What is the common feature of the electronic configurations of the elements in group 7?

(b) Supply the missing word from those in the brackets:
(i) If an element has a low ionization energy then it is likely to be _________ (metallic/non-metallic).
(ii) If an element has seven electrons in its outermost shell then it is likely to have the ________ (largest/smallest) atomic size among all the elements in the same period.

(c) (i) The metals of Group 2 from top to bottom are: Be, Mg, Ca, Sr, Ba. Which of these metals will form ions most readily and why?
(ii) What property of an element is measured by electronegativity?

Answer 1

(a) (i) The first element in period 2 is Lithium (Li) and the last element is Neon (Ne).

(ii) The atomic size of the elements increases on moving down the group, as the number of electronic shells increases and the nuclear charge also increases. However, the effect of increase in nuclear charge is much less than the effect of increase in number of shells.
(iii) Chlorine has the greatest electron affinity among the halogens.
(iv) In group 7, the elements have seven electrons in their valence shell, which is the common feature of their electronic configuration.

(b) (i) If an element has a low ionisation energy then it is likely to be metallic.

(ii) If an element has seven electrons in its outermost shell then it is likely to have the smallest atomic size among all the elements in the same period.

(c) (i) Among all the elements of group 2 barium (Ba) will form ions most readily because it has the largest atomic size, due to which it has the lowest ionisation energy.

(ii) Electronegativity is the measure of the tendency of an element in a molecule to attract the bonding pair of electrons towards itself.