Because the alkali metals are the group 1 metals, they have only 1 valence electron that they want to lose, and the halogens are the group 17 nonmetals, they want to gain 1 valence electron to become stable.
Answer:
the formula that represents a polar molecule is NH3 the 3 is small and toward the bottom
The mass of an atom is given by the sum of the number of PROTONS and the number of NEUTRONS since ELETRON'S mass is negligible.
The mass is 24+28 = 52.
Human teeth are made up of four different types of tissues.