Alkali metals, alkaline earth metals, and aluminum all form ions with positive charges equal to the
a. atomic number.
b. group number.
c. period.
d. atomic mass.

b. group number.

Explanation:

The alkali metals are located in group 1 of the periodic table and are the following: lithium, sodium, potassium, rubidium, cesium and francium and form ions with a positive charge because they are in group 1 of the periodic table .

The alkaline earth metals are located in group 2 of the periodic table and are the following: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radius (Ra) and form ions with two positive charges because they are in group 2 of the periodic table.

The aluminum is embedded within the set of other metals and belongs to group 3A and therefore can form an ion with 3 positive charges.

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8