Question

For each pair of atoms listed (with electronegativity) predict if the bond formed would be A. Covalent B. Polar Covalent C. Ionic

Mg (1.31) and O (3.44) ____________ Be (1.57) and N (3.04) ______________

C (2.55) and O (3.44) ____________ Si (1.90) and Br (2.96) ______________

C (2.55) and Si (1.90) ____________ Ca (1.00) and Cl (3.16) _____________

B (2.04) and N (3.04) _____________ Cl (3.16) and Br (2.96) ______________

Answer 1

Ionic Bond- The bond formed by the complete tranference of electrons from metal to non-metal results into cationic and anionic species having strong electrostatic force of attraction between cation and anion.It is the strongest bond known in chemistry.This bond can predict when electronegativity difference is greater than 2.00.

Covalent Bond- This bond is formed when two atoms having same electronegativity or having very little difference in electronegativity ie.less than 0.5 share equal electrons between these two bonded atoms.

Polar Covalent Bond- The bond is formed when there is unequal sharing of electrons between the bonded atoms in simple words, when one atom has little high electronegativity and other atom is less electronegative. The nature of bond can be predict when electronegativity difference is between 0.5-1.6.

So according to this definition, we can predict the nature of bond between the given atoms:-

Mg(1.31) and O(3.44) - Electronegativity difference is 2.13 so bond formed is IONIC

C(2.55) and O(3.44) - Electronegative difference is 0.65 so bond formed is polar covalent as Oxygen is electronegative atom than carbon.

C(2.55) and Si (1.90) - Both atoms are of same group -14 in periodic table . Hence there is no huge differences in them , So bond formed between two can be considered as Covalent.

B(2.04) and N(3.04)- Electronegative difference is 1.00 so bond is polar covalent.

Be (1.57) and N(3.04)- Electronegative difference is 1.27 and also Beryllium cannot forms ionic bonds due to small size and high charge density as its polarising power is maximum. The bond formed is polar covalent.

Si(1.90) and Br (2.96) - Electronegative difference is 1.06 and secondly bromine is a halogen atom , in periodic table halogens are considered as highly electronegative atoms so due to high electronegativity atoms , bromine pull the electrons towards itself from silicon. The bond formed is polar covalent.

Ca (1.00) and Cl (3.16) - There is huge differences in electronegativities as 2.16 . so clearly the bond is IONIC.

Cl (3.16) and Br (2.96)- Difference in electronegativities is 0.20 . The bond is COVALENT. As difference is very very less .The compound formed by these two atoms are also known as interhalogen compounds.