Question

How can I calculate the valence electrons of ions?

Answer 1

We know that atoms are known to be neutral in original states of any element. This means that the number of protons are equal to the number of electrons. Valence electrons of any atom are the number of electrons that are present in the outermost shell of that atom. Also these electrons are the ones involved in the bonding of the atom

Complete step-by-step answer: Valence electrons are important to be known as they determine the stability of the atom and to know what the atoms want for the same. To make the atom stable, the octet rule is followed by filling their valence shells which are the outermost shells. To attain stability, elements have their atoms to attain stability by being like noble gases who are not reactive as their valence shells are already full.
Let's assume you're using a table that has the groups numbered $1 - 18$. The electron configurations of ions are those of the neutral atoms plus or minus a number of electrons equal to the charge on the ion.
Write the electronic structure for the neutral atom. Then add electrons to get a total of eight.
E.g., for $Cl - \;$ we get:
$Cl:1{s^2}2{s^2}2{p^6}3{s^2}3{p^5}$but $Cl - \;$has one more electron.
Hence, $Cl:1{s^2}2{s^2}2{p^6}3{s^2}3{p^5}$

Note: Ions are known to be consisting of charges as they have either lost or gained electrons to become stable with a full valence shell. When moving of electrons occurs, this causes change of charge. When a neutral atom gains electrons, it becomes negatively charged and becomes an anion. When there is a loss of electrons in a neutral atom, a positive ion is formed and thus called cation.