Question

Atoms can form a variety of bonds with other atoms. Example of bonding types include ionic, covalent, and metallic.

Element	$1^{st}I.E.$	$2^{nd}I.E.$	$3^{rd}I.E.$	Electronegativity
$Al$	$580kJ/mol$	$1820kJ/mol$	$2740kJ/mol$	$1.5$
$C$	$1100kJ/mol$	N/A	N/A	$2.5$
$H$	$1310kJ/mol$	N/A	N/A	$2.1$
$B$	$800kJ/mol$	N/A	N/A	$2.0$
$F$	$1680kJ/mol$	N/A	N/A	$4.0$
$Mg$	$735kJ/mol$	$1450kJ/mol$	N/A	$1.2$

Based on the information in the table above which of the following substances is composed of ionic bonds?

• A. $Mg{F}_2$
• B. $C{H}_4$
• C. $B{F}_3$
• D. None of these

Answer 1

Answer: (A)

$Mg{F}_2$

If the difference between the electronegativities of elements is greater than 1.7, then they will form ionic bonds. Here the difference between electronegativities of 'Mg' and 'F' is

4-1.2 =2.8 which is greater than 1.7

So they form ionic bonds and results in formation of MgF${}_2$