Answer
3 elements: sodium, magnesium, and aluminum
Work Step by Step
The third row of the periodic table begins with sodium. This third row contains only groups 1, 2, 13, 14, 15, 16, 17, and 18. Only groups 1 and 2 are metals whereas group 13 contains both metals and nonmetals; groups 14 through 18 either contain metalloids or nonmetals. Group 1, row 3 element is sodium, a metal; group 2, row 3 element is magnesium, a metal; group 13, row 3 element is also a metal: aluminum.
