Which of the following has three electrons in its valence shell? carbon aluminum sodium calcium

Aluminium

Explanation:

Electrons in an atom will spin around the nucleus at very high speeds. They are negatively charged particles, so they will be attracted to the nucleus (a positive charge), but they will repel other electrons. They form orbital levels (or another name would be valence shells), so that they will not collide with each other.

In the periodic table, you have groups 1 through to 18, and each element has similar properties to the other elements in its group. Group 1 and 17 are the most reactive, because they have one too many (group 1) or one too few (group 17) electrons to make their valence shell a full octet (as can be seen in the noble gasses in group 18). As you go across the groups, group 1 has 1 extra electron, group 2 has 2 extra electrons, group 3 has 3 extra electrons, and so forth.

This means that, if the element has 3 electrons in its valence shell, it will be in group 3, and the only element, out of the given options, in group 3 is aluminium.

Note that it specifies 3 electrons in its valence shell, not 3 electrons overall.

trig 15.3 cos