write the formulas and give the names of the compounds formed by the following ions a) Cr^2+ and F^- b) Ni^2+ and O^2 and c) Fe^3+ and O^2-
CrF2
NiO
Fe2O3
Do you know how to do these? If not you need to learn to do them. You want to make the subscripts (which we don't write as subscripts on these boards--that is, we make them as in CrF2 in which the 2 is understood to be a subscript.) so that the charges on the two ions add to zero. For example, Cr+2 and 2F ad -1 each will give CrF2. For Ni at +2 and O and -2, NiO would be neutral. etc.
To determine the formulas and names of compounds formed by the given ions, we need to consider the charges of each ion and balance them to form a neutral compound.
a) Cr^2+ and F^-
The Cr^2+ ion has a charge of +2, and the F^- ion has a charge of -1. To balance the charges, we need two fluoride ions (F^-) for every one chromium ion (Cr^2+). This means the formula and name of the compound formed are:
Formula: CrF2
Name: Chromium(II) fluoride
b) Ni^2+ and O^2-
The Ni^2+ ion has a charge of +2, and the O^2- ion has a charge of -2. To balance the charges, we only need one oxide ion (O^2-) for every one nickel ion (Ni^2+). This means the formula and name of the compound formed are:
Formula: NiO
Name: Nickel(II) oxide
c) Fe^3+ and O^2-
The Fe^3+ ion has a charge of +3, and the O^2- ion has a charge of -2. To balance the charges, we need two oxide ions (O^2-) for every one iron ion (Fe^3+). This means the formula and name of the compound formed are:
Formula: Fe2O3
Name: Iron(III) oxide
By following the rules of charge balance, we can determine the formulas and names of compounds formed by different ions.