Final answer:
To properly name a monatomic main group cation, use the element name followed by 'ion'. In binary ionic compounds, name the cation first and the anion by dropping 'ion' and adding '-ide'. Variable charge cations are named with Roman numerals.
Step-by-step explanation:
The proper way to name a monatomic main group cation is to use the name of the element followed by the word ion. For example, sodium ion is written as Na+, aluminum ion is written as Al3+, and calcium ion is written as Ca2+. This naming convention applies to monatomic cations of main group elements.
When naming simple binary ionic compounds, the cation is named first using the name of the element, followed by the anion. The anion is named by changing the element name ending to -ide. For example, Ba(NO3)2 is named barium nitrate.
In cases where the cation has a variable charge, the charge is indicated in Roman numerals enclosed in parentheses. For example, Fe2+ is named iron(II) ion and Fe3+ is named iron(III) ion.