Why changes of state are considered physical transition and not chemical processes

In a physical change, the chemical compontents are not altered. If ice melts into a liquid it's still water regardless; same goes if it were to vaporize and turn into a gas.

In a chemical change, the chemical components are altered. If you left a metal outside after it rained it would rust which would be a chemical process since it is chemically altered. Flamability is also a chemical process.

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.