The halogens, alkali metals, and alkaline earth metals have valence electrons, respectively.

The halogens, alkali metals, and alkaline earth metals have 7, 1, and 2 valence electrons, respectively.

The following information regarding the valence electrons is:

Halogen - 7 elements that required one electron for the octet rule that could be accomplished. Alkali metals - one element that lost the single electron for creating the octet and cation.Alkaline Earth meals - 2 elements that lost two electrons for creating 2 + cations.

Learn more: link

The valence electrons are as follows for these groups of elements:

Halogen- SEVEN  (halogens are group 7 elements that need one electron for the octet rule to be achieved)

Alkali Metals - ONE  (these are group one elements that lose a single electron to form an octet and cation)

Alkaline Earth Metals - TWO (group two elements that lose two electrons to form 2+ cations)

Gallium melts near room temperature and has one of the largest  liquid  ranges of any metal, so it has found use in high temperature thermometers.

Bar graph