Answer
The Lewis symbol for $Sn^{2+}$ is seen in the diagram.
Work Step by Step
RULES TO WRITE LEWIS SYMBOL
- Find out the number of valence electrons in the atom.
- Write the element symbol and around it present each valence electron with one dot to the top, bottom, right or left of that symbol.
- Spread out the dots as much as possible (so there would be minimum electron-electron repulsions), and no spots can hold over 2 electrons.
1) $Sn$ is in group 4A, so a neutral $Sn$ atom has 4 electrons in the outermost occupied shell.
However, cation $Sn^{2+}$ already loses 2 electrons compared with its neutral $Sn$ atom. So, $Sn^{2+}$ only has 2 electrons in the outermost occupied shell.
That means $Sn^{2+}$ has 2 valence electrons. The Lewis symbol of $Sn^{2+}$ would have 2 dots.
2) The dots must spread out as much as possible. So each of the 2 dots would occupy a spot of its own.
Eventually, there are 2 spots with 1 electron, and 2 empty spots.
