posted by sam .
The question list each element and the numebr of atoms
Mg = magnesium
What does OH with brackets aorund it mean and then the small 2
OH is an element known as Hydroxide, and the 2 indicates that there are 2 of them present.
Err, I meant to say compound not element. OH is a compound of oxygen and hydrogen. The 2 indicates there are 2 of this compounds present, which means that there are 2 of each element present.
OH is neither a compound nor an element. OH^- is the hydroxyl ion (or hydroxide ion). When paired with Mg ion it forms Mg(OH)2which is named magnesium hydroxide. The 2, when placed as a subscript after a set of parentheses, multiplies everything inside the parentheses by 2. Thus, there is 1 Mg atom, 2 O atoms, and 2 H atoms in a molecule of magnesium hydroxide.
it means that the O (oxygen) and the H (hydorgen)there are two of them.