If you have a magnesium for every oxygen, then you have to start with two magnesiums. So the balanced equation is 2 Mg + O2 2 MgO.
And
CaCO3———→CaO + CO2
I hope it helped!
Silver has metallic bonding.
Silver is a very typical and main metal. The negatively charged electrons distribute themselves throughout the entire piece of metal and form non directional bonds between the positive silver ions, which is metallic bonding, and what silver contributes.
An element is just consisted of one type of atom and cannot be broken down by chemicals (Ex. Oxygen just has the oxygen molecule)
A compound is when there's a mixture of atoms and can be broken down by chemicals (Ex. NaCl is made up of sodium and chloride atoms)