Predict the chemical formula for the ionic compound formed by (c) Al 3+ and CH3COO–
Okay guys, so here we have to predict the chemical formula for the ionic compound that is going to be formed when you have aluminium and acetate ion, CH3COO- .
So the key here is to look at the charges, are the charges the same or different. In this case they're different, because we have three for aluminium and one for acetate, so, since they're different, the numbers will criss-cross, they're not cancelling each other out. So the three from aluminium is going to go to the acetate and the one from the acetate is going to go to the aluminium. Alright, so the way we would write this would be, we have aluminium one, from the acetate is imaginary, and then we would put acetate in the parenthesis, because this is one of your polyatomic ions, and the three would go outside of that, because when you're criss-crossing the numbers, if it is a polyatomic ion it goes for all of the atoms that are inside. So the three gets distributed to every single atom inside the parenthesis. If you don't put the parenthesis, for example, we're assuming that this three only belongs to this oxygen. Alright, so that's why the parenthesis are very important.
So this is your final answer, let's move on.