Covalent bonds generally form when the bonded elements have a difference in electronegativity less than 1.5. Subtract the electronegativities for the following pairs of elements and predict whether they form a covalent bond.

The answer to your question is a) Covalent    b) Ionic

Explanation:

Data

Kind of bond between C - C

kind of bond between Mg -Cl

Process

1.- Look for the electronegativities of these elements

Carbon electronegativity = 2.55

Magnesium electronegativity = 1.31

Chlorine electronegativity = 3.16

2.- Calculate the difference of electronegativities

a) C - C = 2.55 - 2.55 = 0          

b) Mg - Cl = 3.16 - 1.31 = 1.85

3.- Kind of bond

a) It's covalent because the difference of electronegativity was lower than

    1.5.

b) It's ionic because the difference of electronegativity was higher than 1.5.  

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