# Naming of hydroxides

In naming of compound, for example in strong base; KOH and $\ce{Ca(OH)2}$ have different formula, in potassium hydroxide, one hydroxyl group is attached while in calcium hydroxide two hydroxyl group are present, but both named hydroxide, please explain.

• First, do you know why "one hydroxyl group is attached" in KOH and two in $\ce{Ca(OH)2}$? – M.A.R. Aug 1 '16 at 6:35
• – user7951 Aug 1 '16 at 9:49
• Related: How are ionic formulas written? – user7951 Aug 1 '16 at 11:46