Elements P, Q, R and S have atomic numbers 11, 15, 17 and 18 respectively. Which of them are reactive non-metals?
(a) P and Q
(b) P and R
(c) Q and R
(d) R and S
The electronic configurations of P, Q, R and S are as follows:
P(11): 2, 8, 1
Q(15): 2, 8, 5
R(17): 2, 8, 7
S(18): 2, 8, 8
Metals lose electrons to attain stability whereas non-metals gain electrons for the same.
Now, checking the options:
- Element P donates 1 electron to attain stability. Hence, it is a metal.
- Element Q accepts 3 electrons to attain stability. Hence it is a non-metal.
- Element R accepts 2 electrons to attain stability. Hence it is a non-metal.
- Element S cannot accept anymore electrons. Hence, it is a noble-gas.
Since Q and R have a high tendency to accept electrons in order to attain noble gas configuration, they are reactive non-metals.
Therefore, the correct option is (c) Q and R