Question

a) Complete the table below with the elements E,F,G,H such that E is an inert gas having electronic configuration 2,8.

Elements	Atomic number	Electronic configuration
E	Z	2,8
F	Z-1	______
G	Z+1	_______
H	Z+4	________

b) Which of the elements E, F, G, and H given in the above table will be a?

i) metal

ii) non-metal

iii) state the formula when

a) F and G combine

b)F and H combine

Answer 1

a)

• Element E has atomic number Z . An electrically neutral atom will have an equal number of electrons and protons. Thus it will have (2+8)=10 electrons and protons.
• The element F has atomic number Z-1 means it will have Z= (10-1)=9. Thus electronic configuration:2,7.
• The element G has atomic number Z+1 means it will have Z= (10+1)=11.Thus electronic configuration:2,8,1.
• The element H has atomic number Z+4 means it will have Z= (10+4)=14. Thus electronic configuration:2,8,4.

Elements	Atomic number	Electronic configuration
E	Z	2,8
F	Z-1	2,7
G	Z+1	2,8,1
H	Z+4	2,8,4

b)

i) G will be metal as it has electronic configuration:2,8,1. It has only one electron in the valence shell and hence it will have a tendency to give up this electron and attain a stable electronic configuration.

ii) Both F and H will be non-metals as they have 7 and 4 electrons in their valence shell respectively. Elements with 4 to 7 electrons in their valence shell will have a tendency to accept more electrons and complete their octet. Hence both of them are non-metals.

iii)

a) F has electronic configuration:2,7.It is a nonmetal with 7 valence electrons, it needs one more electron to attain its octet.

G has electronic configuration:2,8,1.It is a metal atom with one valence electron. It will have a tendency to give up that electron and attain octet.

Thus when F and G combine G gives up one electron and F accepts that electron. They will form GF molecules.

b) F has electronic configuration:2,7.It is a nonmetal with 7 valence electrons, it needs one more electron to attain its octet.

H has electronic configuration:2,8,4.

Thus four F atoms and one H atom come together. Each F atom will make a bond with the F atom by donating a single electron. Thus H atom gets four more electrons and a complete octet. Now both F and H can complete their octet. They form ${\mathrm{HF}}_4$ molecule.