Answer: element.
Justification:
1) A molecule is the union of two or more atoms.
2) When two or more atoms of different elements bond together, the molecule formed is a compound.
For example: one atoms of hydrogen and one atom of chlorine form the molecule HCl, which is a compound (hydrogen chloride).
3) When the molecules is formed by two atoms of the same element, it is not called a compound, but element. Some examples of this are the diatomic gases:
H₂: hydrogen
Cl₂: chlorine
Br₂: bromine
O₂: oxygen
S₂: sulfur
N₂: nitrogen.
the chemical equation will be XY2
Think of it as a balloon when you pump air into it it grows bigger but, if you put too much air into it what happens it pops because the pressure was too much for the balloon to withhold. That's the same with a basketball when you pump air into it the pressure pushing on the material increases. <span />
The electron configuration for magnesium is 1s22s22p63s2
