Composition of the nuclei of two atomic species A and B are given below:

A B

Protons 11 17

Neutron 12 18

(a) State the mass numbers of A and B

(b) What is the charge on the ions formed by atoms A and B?

(c) Write the formula when A reacts with B.

Explanation:(a) mass number = atomic number + number of neutrons

(the atomic number is the number of protons of an element)

mass number of A = 11 + 12 = 23

mass number of B = 17 + 18 = 35

(b) +1 and -1, respectively

(c) A+ + B- → AB (the first plus sign and the minus sign are superscripts)