What is the bond used between zinc acetate? How to learn to write such formulas?

The bond used between zinc acetate is ionic, and the easier way to learn to write such a formula is to learn to place the ions first, and then crisscross their charges.

The bond that forms zinc acetate is ionic. Zinc forms 2+ cations, with the formula ##"Zn"^(2+)## and acetate is a polyatomic anion with the formula ##"C"_2"H"_3"O"_2"^−##.

Since the compound needs to be neutral, the total positive charge must equal the total negative charge, so the formula for zinc acetate requires one ##"Zn"^(2+)## and two ##"C"_2"H"_3"O"_2"^−## ions.

The formula is then ##"Zn"("C"_2"H"_3"O"_2)_2##. The formula for the acetate ion is placed in parentheses with a subscript of 2, indicating that two acetate ions with a 1- charge are required to bond with one zinc ion with a 2+ charge. Now the total positive charge is 2+ and the total negative charge is 2-, giving an overall charge of zero for the zinc acetate compound.

A very easy method for is called the crisscross method. It is shown in the diagram below.

Since a chemical formula for an ionic compound must indicate the lowest whole-number ratio of ions, sometimes after crisscrossing you must reduce the ratio.