Write the electronic configuration of the element with atomic number 17. Indicate the valency of the element.

Complete the following statements:

(a) Magnesium has 3 valence electrons in the ………… shell.

(b) The valency of nitrogen in N₂ molecule is ……….

(c) Isotopes have different mass numbers because their nuclei contain different number of ……….

(d) Some boron atoms have mass number 10 and some have mass number 11. These boron atoms with different mass number are called ……...

The nucleus of an atom has 5 protons and 6 neutrons. What would be the

(a) atomic number,

(b) mass number,

(c) the number of electrons, and

(d) the number of valence electrons, per atom of this element?

The atomic number of an element X is 16.

(a) Write down the electronic configuration of X.

(b) What will be the valency of X?

What valencies will be shown by the elements A, B, C, D and E having atomic numbers 2, 4, 8, 10, and 13 respectively.