The electronegativity is 2.1 for H and 1.8 for Si. Based on these electronegativities, #SiH_4# would be expected ?A) be ionic and contain H+ ions (B) be ionic and contain H- ions (C) have polar covalent bonds with a partial negative charges on the H atoms

Question

Avery Adams · Accepted Answer

possess polar covalent bonds on the hydrogen atoms that are partially negatively charged. This is the correct response.

If you just consider the options provided, the answer should be clear because there isn't much of a difference in electronegativity between the two atoms, ruling out the possibility that their bond has a predominantly ionic character.

The difference in electronegativity between the two atoms in a bond must be greater than 1.7 in order for it to be classified as ionic, which is not the case in your example.

However, there's an interesting comparison to be made with the famous #"C-H"# bond.

The difference in electronegativity for both bonds is approximately 0.3, but the #"C-H"# bond is considered to be nonpolar covalent, while the #"Si-H"# bond is considered to be polar covalent.

As silicon has a larger atom than carbon, its electron cloud will also be larger, which means that silicon is more polarizable than carbon.

In the case of the #"Si-H"# bond, this will allow the more electronegative hydrogen to distort silicon's electron cloud and produce two partial charges, a positive one on the silicon and a negative one on the hydrogen.

With a negative partial charge on the hydrogen atom, the bond between silicon and hydrogen will therefore be regarded as polar covalent.

Olivia Anton · Answer

undefined C) have polar covalent bonds with partial negative charges on the H atoms.