List three things you would need to consider to determine whether or not a chemical system is at equilibrium?

First of all you need a chemical system ie a system in which there are at least two reactants to start with. Then there needs to be a reaction between the reactants so that products are being created. Finally it needs to be determined at what point there are no more products being created, and that then should represent equilibrium.

If a hydrogen atom is neutral, it must also have  one electron. an oxygen atom (o) has an atomic number of eight (8). this means a neutral oxygen atom has eight protons and eight electrons. the element actium (ac) has an atomic number of 89, so it has 89 protons and 89 electrons in a neutral atom