Question 3.27

[Robert Estrada]

Can someone please explain #27 and how you find the chemical formulas?
a. thallium(III) oxide
b. manganese(II) chloride
c lithium nitride

[Madelyn Gehrich 1E]

a. Thallium (III) oxide. It indicates to you that in this compound, the thallium ion will be taking the 3+ form. Knowing that oxygen forms a 2- ion, you cross the charges to form the compound Tl2O3.
b. Manganese (II) chloride. It indicates to you that in this compound, the manganese ion will be taking the 2+ form. Knowing that the chlorine forms a 1- ion, you cross the charges to form the compound MnCl2.
c. Lithium nitride. Knowing that lithium forms a 1+ ion and nitrogen forms a 3- ion, you cross the charges to form the compound Li3N.

[Isita Tripathi 2E]

Just to clarify, the reason you cross the charges is because in order to obtain the chemical formula for the neutral compound, the charges have to cancel. So for c for example, it takes 3 Li + ions to cancel the 3- charge of one Nitrogen atom. The chemical formula is always the lowest amount of atoms that it takes to create the neutral compound, so make sure you reduce if needed.