Sodium bicarbonate is the chemical name for baking powder. Its chemical formula is NaHCO3. What does the subscript 3 mean? A.
There are three molecules of sodium bicarbonate.
B.
There are three molecules of oxygen in sodium bicarbonate.
C.
There are three atoms of oxygen in sodium bicarbonate.
D.
There are three atoms of sodium bicarbonate.

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.

you need to stop taking that class