Unit 4 Review: Valence Electrons, Dot Symbols, and Diatomic Elements

Vocabulary and key concept flashcards reviewing periodic groups, valence electrons, Lewis dot placement rules, and diatomic elements from the Unit 4 Review Worksheet.

Dot placement rule (single atoms)

The procedure of starting at the top, moving clockwise to place one dot on each side first, and then pairing up dots in the same order.

Group 1 valence electrons

Elements in Group $1$ (such as $\text{Li}$ and $\text{K}$) have $1$ valence electron.

Group 2 valence electrons

Elements in Group $2$ (such as $\text{Mg}$ and $\text{Be}$) have $2$ valence electrons.

Group 13 valence electrons

Elements in Group $13$ (such as $\text{Al}$ and $\text{B}$) have $3$ valence electrons.

Group 14 valence electrons

Elements in Group $14$ (such as $\text{C}$ and $\text{Si}$) have $4$ valence electrons.

Group 15 valence electrons

Elements in Group $15$ (such as $\text{N}$ and $\text{P}$) have $5$ valence electrons.

Group 16 valence electrons

Elements in Group $16$ (such as $\text{O}$ and $\text{S}$) have $6$ valence electrons.

Group 17 valence electrons

Elements in Group $17$ (such as $\text{F}$, $\text{Cl}$, and $\text{Br}$) have $7$ valence electrons.

Group 18 valence electrons

Noble gas elements such as $\text{Ne}$ that have $8$ valence electrons, with the exception of $\text{He}$, which has $2$.

Carbon dot symbol

A dot structure consisting of $4$ dots, all single, placed one on each side around the symbol $\text{C}$.

Diatomic elements

The seven elements that exist naturally as two-atom bonded molecules: $\text{H}_2$, $\text{N}_2$, $\text{O}_2$, $\text{F}_2$, $\text{Cl}_2$, $\text{Br}_2$, and $\text{I}_2$.

Electron sharing stability in diatomic molecules

A state achieved when two atoms share their unpaired electrons so that each obtains a full outer shell, resulting in higher stability and lower energy compared to lone atoms.