. Based on the periodic table, magnesium (Mg) has two valence electrons. What could you infer about the number of valence electrons of calcium (Ca)?
A. Calcium (Ca) has one more valence electron than magnesium (Mg) because
it is below Mg and in the same family.
B. Calcium (Ca) has one less valence electron than magnesium (Mg) because it
is below Mg and in the same family.
C. Calcium (Ca) has the same number of valence electrons as magnesium (Mg)
because it is below Mg and in the same family.

the answer for sodium is 0.186

the answer for rubidium is 0.251

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.

explanation:

a