What are the conditions that atoms need to form molecules

Electrons group themselves in pairs in their energy levels. To calculate the number of electrons allowed in any energy level, find the square of the number representing the energy level and multiply it by two. Using this formula, atoms can have two electrons in their first energy level, eight in the second, and eighteen in their third. The quantity of electrons at each level grows as the number of the energy level increases.

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.