Question

Which of the following statements regarding Lewis dot symbols of ions is false?

Which of the following statements regarding Lewis dot symbols of ions is false?

	Mg2+ always has one electron around it.
	In ionic compounds containing chloride, ions, Cl− is isoelectronic with Ar.
	In magnesium sulfide, S2− has eight electrons.
	In sodium chloride, Na+ has no electrons around it.

Answer 1

Lewis structures show the connections between atoms in a molecule or ion using only the valence electrons of the atoms involved.

Mg2+ always has one electron around it.

This statement is false.

The Lewis dot for Mg2+ is Mg with no dots, since there are no electrons in the open shell. Essentially Mg2+ is isoelectronic (has same electronic configuration) as neon. It is a closed shell.

In ionic compounds containing chloride, ions, Cl− is isoelectronic with Ar.

This stament is correct.

Since Cl has 7 electrons to begin with, and it has just gained an extra electron, its lewis dot structure will have 8 dots. . Essentially Cl- is isoelectronic (has same electronic configuration) as Ar. It is a closed shell.

In magnesium sulfide, S2− has eight electrons.

This stament is correct.

Since S has 6 electrons to begin with, and it has just gained two electron, its lewis dot structure will have 8 dots.

In sodium chloride, Na+ has no electrons around it.

This stament is correct.

Since Na has 1 electron to begin with, and it has just removed 1electron, its lewis dot structure will have 8 dots. It is a closed shell.