How do you know the charge of a +1 cations of sodium?

If the atoms of an element always have the same charge, the Roman numeral is unnecessary (and considered to be incorrect.) For example, all actions formed from sodium atoms have a +1 charge, so Na+ is named sodium ion without the Roman numeral for the charge.

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