(a) Nitrogen has relatively stable isotopes (half-life greater than 1 second) of mass numbers

13, 14, 15, 16, and 17. (All except 14N and 15N are radioactive.) Calculate how many protons and neutrons are in each of these isotopes of nitrogen.

(b) Write the electronic configurations of the third-row elements shown in the partial periodic table in Figure 1-5.

Solution:

Find:

Here we have to calculate number of protons and neutrons are in each of these isotopes of nitrogen and electronic configuration of the third-row elements.

Given:

Mass numbers of various isotopes of N = 13, 14, 15, 16, and 17

Step 1

The atomic number(Z) of N is 7.

It is known that number of neutron (n) = mass no. (A) - atomic number (Z)

For 13N: number of proton 7P, number of neutron (13-7=6 ) 6N

For 14N: number of proton 7P, number of neutron (14-7= 7) 7N

For 15N: number of proton 7P, number of neutron (15-7= 8) 8N

For 16N: number of proton 7P , number of neutron (16-7=9) 9N

For 17N: number of proton 7P, number of neutron(17-7= 10)10N