# What is the number of valence electrons in tin?

Jun 27, 2016

Tin has $4$ valence electrons.

#### Explanation:

The quick answer here is that because tin, $\text{Sn}$, is a main-group element, the number of valance electrons will be given by its group number.

Tin is located in group $1 \textcolor{red}{4}$ of the periodic table, which means that it has $\textcolor{red}{4}$ electrons in its outermost shell, i.e. $\textcolor{red}{4}$ valence electrons.

Now, you can prove that this is the case by constructing tin's electron configuration.

Tin has an atomic number of $50$, so right from the start you know that its electron configuration must account for a total of $50$ electrons. You will have

$\text{Sn: } 1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 3 {d}^{10} 4 {s}^{2} 4 {p}^{6} 4 {d}^{10} \textcolor{b l u e}{5} {s}^{\textcolor{red}{2}} \textcolor{b l u e}{5} {p}^{\textcolor{red}{2}}$

The fifth energy level, $n = \textcolor{b l u e}{5}$, is tin's outermost energy shell. As you can see, tin has a total of $\textcolor{red}{4}$ electrons on this level

• $\textcolor{red}{2}$ electrons in the $5 s$ subshell
• $\textcolor{red}{2}$ electrons in the $5 p$ subshell

Once again, you can conclude that tin has $\textcolor{red}{4}$ valence electrons.