help with a periodic trend problem?

[Kylie McCauley 1D]

Hi,

Can someone please explain why MgS is the right answer?

Which of the following compounds below has bonds with the most covalent character?
A. Li2O
B. MgS
C.CaO
D. MgO
E. CaS

[Nina Ellefsen 2D]

Hi! In this example, the difference in electronegativity between the atoms in MgS is smaller than the difference in electronegativity between the atoms in any of the other given compounds.

[Jade_Tai_2L]

Does this question have to do with the highly polarizable e-? Like, highly polarizable e- makes the molecule have a more covalent character? (Or am I getting this wrong)

[Mikayla Kwok 3K]

I think MgS is the answer, because Mg2+ is a small, highly charged cation, which makes it very polarizing, and S2- is a relatively large anion, which makes it polarizable. These characteristics cause the Mg2+ ion to pull more electrons from S2- into a shared region, which gives the ionic bond more covalent character.

[Irene Kim 3E]

It might help to consider the relative electronegativities of each atom involved in the compound. As an example, a molecule of water, H₂O, would have high covalent character because the oxygen is more electronegative than hydrogen, causing opposite partial charges within the molecule. On the other hand, a compound like CH₄ would have a lower covalent character, because carbon and hydrogen are closer in electronegativity.