How does a molecular substance differs from a ionic substance ?

Molecular is existent due to being made out of molecules, and thus taking up space until a container cannot hold more.
Ionic substances are a little different they are made out of energy, thus taking up only the amount of energy a certain area can handle. Ionic substances also will show motion of energy as well.

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