Question

How do you figure out how many electrons a sodium ion has? Can it be determined with a flame test?

Answer 1

`"through the info provided in the periodic table and mathematical calculations"`

Explanation:

Flame test does not in any way provides the number of electrons of sodium ion, but determines only the presence of that particular ion. The method is just a qualitative determination for the presence of ions in substances tested, though electrons are involved in the process, but quantity of it is beyond measurable.

The periodic table provides all the important information regarding elements. Remember that `"an atomic number is equal to the number of electrons and number of protons"` if an atom is in neutral state. If in ionic form, it depends whether it is metallic or nonmetallic because these info tell us whether electrons are gained or lost in an atom.
Metallic is known to lose its valance electron to achieve the noble gas configuration that precedes it. While Nonmetallic substances are known to gain electrons to achieve stability. In this case, sodium is classified as a metal and thus loss its single valence electron to have the noble gas configuration to achieve stability; i.e.,

`"For Na atom"`
`"Atomic number"=11`
`"No. of " p^+=11`
`"No. of "e^(-)=11`

`"For " Na^(+) ion`
`"Atomic number"=11`
`"No. of " p^(+)=11`
`"No. of "e^(-)=10`

The decrease in number of electron of the latter is due to the fact that `Na` atom has to lose its single valance electron to achieve stability forming `Na^(+)`, a cation.