Question

The elements A, B, and C belong to groups 1, 14, and 17 respectively of the periodic table.
(A) Which two elements will form a covalent compound?
(B) Which two elements will form an ionic compound?

Answer 1

Hint: To determine the bond formation of the elements, we first need to know the characteristics of the groups of 1, 14, and 17. In a group, all the elements have the same number of valence electrons and hence the elements have similar properties.

Complete answer:
Let first understand what are covalent bonds and ionic compounds.
When a molecule is formed through covalent bonding, it is known as a covalent compound. In a covalent bond, when valence electrons are shared between the atoms. The atoms which participate in bond formation are electrically neutral.
Usually, covalent bonds are formed between two nonmetals.
When oppositely charged ions of a chemical compound are bonded by the electrostatic attraction between them, the bonds formed are also known as ionic bonds and the compound formed is known as an ionic compound.
An ionic compound is usually formed when a metal and a nonmetal react.
Now let us understand the group characteristics of groups 1, 14, and 17.
Group 1:
The elements in group 1 are known as alkali metals and lie in the s-block. They include lithium, sodium, potassium, rubidium, cesium, and francium.
The elements have one electron in their valence shell, which they lose quickly to form ions with +1 charge and attain complete outermost octet configuration.
These ions form bonds with negatively (-1) charged ions.
Group 14:
Group 14 is also known as the carbon group and lies in the p-block. The elements are carbon, silicon, germanium, tin, lead, and flerovium.
The elements have 4 electrons in their outermost shell. They usually share their valence electrons with other neutral atoms to complete the octet configurations.
Group 17:
The elements of group 17 are also known as the halogens and lie in the p-block. They contain fluorine, chlorine, bromine, iodine, and astatine.
These elements have 7 electrons in their outermost shell. They can form bonds either by gaining an electron to form a (-1) negatively charged ion and reacting with a (+1) positively charged ion or it can share its electrons with other neutral atoms to complete octet configurations.
From the above characteristics, we can say that
(A) Elements B and C will form a covalent compound.
(B) Elements A and C will form an ionic compound.

Note:
It should be noted that the electrons present in the outermost shell, or the valence electrons are the ones that participate in bond formation. Also, it should be noted, as we go down the group, the elements start to show variable valencies.