Calcium forms an ion with a positive 2 charge and chlorine forms an ion with a negative one charg, so the formula is <span>CaC<span>l2</span></span>
Group 1 metals and group 2 metals form positive ions by losing 1 and 2 electrons respectively. Non-metals in group 17 gain 1, group 16 gain 2 and group 15 gain 3. Elements which lose electrons form positive ions while elements that gain electrons form negative ions.
To write a formula, you must balance charges so the overall charge is zero. A simple way to do this is to swap the # of the ion's charge and make it the subscript of the other ion. However, leave off the number 1 and reduce to lowest whole number ratio.
...contains the sulfate anion (SO42−) and is called sulfuric acid; H3PO4<span> contains the phosphate anion (PO43−) and is called phosphoric acid; and HC2H3O2, which contains the acetate ion (C2H3O2−), is c... Phosphoric acid (</span>H3PO4<span>) has three hydrogen atoms, all of which are replaceable by a metal.</span>
