Classify each of the observed changes according to whether or not they are likely to represent evidence that a chemical
reaction is occurring when performing an experiment.

May be evidence of a chemical reaction

Not evidence of a chemical reaction

Answer Bank
a solid liquifying
precipitation
change in temperature
solution colors mixing
a solution color becoming less intense due to dilution
bubbles (gas formation)
changes in color
explosion or fire

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.