Chapter 18, Problem 9STP

To determine

The occurrence of group 17 elements when it reacts with group 1 element.

Answer to Problem 9STP

The correct option is (A).

Explanation of Solution

Given:

Group 17 elements react with the group 1 elements.

Calculation:

The elements of group 17 have 7 valence electrons. Group 17 hasthe following elements: fluorine, chlorine, bromine, iodine, and astatine.

All these elements have 7 electrons in their outermost shell.

The elements of group1 have only one electron in the outer shell. For example sodium (Na).

The atomic number of sodium is 11.

The electronic configuration of Na is $1s^{2}2s^{2}2p^{6}3s^1$ .

If the elements of group 17 react with the elements of group 1, the elements of group 17 gain 1 electrons and form negative ions. These negative ions are also known as anions.

The elements of group 1 lose one electron and form a positive ion. These positive ions are called Cations. Therefore, elements of group 17 form negative ions on reacting with elements of group 1.

Thus, options (B), (C) and (D) are wrong, and option (A) is correct.

Conclusion:

Hence, elements of group 17 form negative ions on reacting with elements of group 1.