Why are valence electrons important?

Afamily is one another name for a group on the table of elements.

Sally is making a model of a magnesium atom with an atomic mass number of 24 for her chemistry class. she has foam balls for the protons, neutrons, and electrons. she has added 6 neutrons to her model so far. how many more neutrons does she need to add to complete her neutral atom of magnesium?

How many grams of co(g) are there in 74.5 ml of the gas at 0.933 atm and 30o c?