Question

Explain why hydrogen will form an ionic bond with fluorine but only forms covalent bonds with carbon

Answer 1

Answer : The hydrogen will form an ionic bond with fluorine but only forms covalent bonds with carbon due to electronegativity difference.

Explanation :

The type of bonding between the atoms forming a compound is determined by using the electronegativity difference between the atoms.

According to the pauling's electronegativity rule:

If $\Delta \chi=0$, then the bond is non-polar.

If $\Delta \chi\leq 1.7$, then the bond will be covalent.

If $\Delta \chi>1.7$, then the bond will be ionic.

As we know that:

Electronegativity for fluorine = 3.98

Electronegativity for hydrogen = 2.1

Electronegativity for carbon = 2.55

Electronegativity difference between HF:

$\Delta \chi=\chi_{F}-\chi_{H}\\\\\Delta \chi=3.98-2.1=1.88$

Electronegativity difference between CH:

$\Delta \chi=\chi_{C}-\chi_{H}\\\\\Delta \chi=2.55-2.1=0.45$

As, electronegativity difference of HF is more than 1.7. Thus, the bond between fluorine and hydrogen is ionic bond.

As, electronegativity difference of CH is less than 1.7. Thus, the bond between carbon and hydrogen is covalent bond.

Answer 2

A fluorine atom has seven valence electrons. ... Carbon will then have five valence electrons (its four and the one its sharing with fluorine). Covalently sharing two electrons is also known as a “single bond.” Carbon will have to form four single bonds with four different fluorine atoms to fill its octet.