On the bonding of NaF
worldly matter, the bonds it constitutes are roughly divided into ionic bonds and covalent bonds. Today, take NaF as an example to analyze its bonding properties.

Sodium (Na) is a metal element with only one electron in the outermost layer of its atom. This electron is loosely bound and volatile, so it forms a positively charged cation ($Na ^ + $). Fluorine (F) is a non-metallic element with seven electrons in the outermost layer of its atom, which is very attractive to electrons. If you want to obtain one electron to reach an eight-electron stable structure, you will form a negatively charged anion ($F ^ - $).

When sodium and fluorine meet, the electrons lost by the sodium atom are obtained by the fluorine atom, and the anions and cations are attracted to each other due to strong electrostatic interaction, which is the essence of ionic bonds. Therefore, NaF is combined by ionic bonds and belongs to ionic compounds.

In contrast, covalent bonds are mostly formed between non-metallic elements, and the atoms reach a stable structure through shared electron pairs. In NaF, sodium is a metal, and fluorine is a non-metal. The bonding method is not a shared electron pair, but the gain and loss of electrons form anions and cations, which in turn form ionic bonds.

From this perspective, NaF has the characteristics of ionic bonds and is not a covalent bond system. This is based on the properties of elements and the bonding method.