Question

Which of the following compounds is not likely to have ionic bonds LiF, NaCI, CH4, MgF2

Answer 1

Answer:

$CH_4$  is not likely to have ionic bonds

Explanation:

Ionic bond is formed between a metal and a non metal.

$NaCl, LiF$ and $MgF_2$ are examples in which we see metal bonded with a non-metal.

Na, Li, Mg are all metals and Cl, F are non metals.

$CH_4$ contains only non metals. Covalent bond is the bond present among non metallic compounds.

We can identify a bond as an ionic bond or a covalent bond based on the electronegativity values of the atoms present in it.

For example $H_2 S$

Hydrogen --> electronegativity value is 2.1

Sulfur --> electronegativity value is 2.5

∆E, the electronegativity difference is 2.5 - 2.1 = 0.4

So, It is a non polar covalent bond present in $H_2 S$

Examples :  

The electronegative values of H is 2.1

F is 4.0

O is 3.5  

N is 3.0

∆E value of HF Hydrogen bond  is

4.0 - 2.1 = 1.9

∆E value of H2O Hydrogen bond is

3.5 - 2.1 = 1.4

∆E value of NH3 Hydrogen bond is

3.0 - 2.1 = 0.9

∆E value between 0.5 to 1.7 is a polar covalent bond

∆E value btween 0 to 0.4 is a non polar covalent bond  

∆E above 1.7 is an ionic bond

Answer 2

Methane CH$_{4}$ does not have ionic bonds. Because of the close value of electronegativity of the carbon and hydrogen atoms the electrons are shared forming covalent bonds.