The Lewis structure of potassium fluoride, potassium (K) is element 19, its electron arrangement is 2, 8, 8, 1, and the outermost layer has 1 electron; fluorine (F) is element 9, its electron arrangement is 2, 7, and the outermost layer has 7 electrons.

When forming a compound, the potassium atom will lose 1 electron in the outermost layer, forming a positively charged potassium ion ($K ^ + $). At this time, the electron layer structure becomes 2, 8, 8, reaching a stable structure. The fluorine atom will gain 1 electron, forming a negatively charged fluoride ion ($F ^ - $), and the electron layer structure becomes 2, 8, also reaching a stable structure.

Potassium ions combine with fluoride ions through ionic bonds to form potassium fluoride (KF). In the Lewis structure representation, potassium ions are represented by $K ^ + $, and fluoride ions represent the outermost 8 electrons (including the obtained 1 electron) with dots or forks around the fluorine symbol, namely: $[:\ underset {·} {\ overset {·} {F }}:]^-$。 The Lewis structure of the overall potassium fluoride can be simply expressed as $K ^ + [:\ underset {·} {\ overset {·} {F }}:]^-$ ， clearly shows the bonding and electron distribution of ions in potassium fluoride.