Think of it this way: it is a distribution problem in which you are multiplying the 2 on the outside with each element in the parentheses. Oxygen does not have a number in front of it, so put an imaginary one in front of it to help you. Do the same with Hydrogen since it doesn't have a number in front of it either. Now you know that hydrogen has one ion and oxygen has one... but you must now multiply each of the elements' ions by two. You should now know that Oxygen has 2 ions in Calcium Hydroxide and that there are also 2 ions of Hydrogen in Calcium Hydroxide. Does this make sense?
In a chemical reaction , the reactants are written on the left hand side followed by a rightarrow and then products are given on the right side of the arrow.
In the given chemical equation :
Reactants are iron (Fe) and oxygen and product is iron oxide .
Covalent compounds don't contain ions because they make bonds by sharing electrons. In addition, they don't have any charge carries that are free to move so they can't carry electric current
