Question 1: What are valence electrons, and how are they related to the way atoms react? Question 2: Explain the "magic number" of helium and the other elements on the periodic table in terms of their valence electrons. What happens when an element reaches this "magic number?"

1:The outermost electrons -- the valence electrons -- are able to interact with other atoms, and, depending on how those electrons interact with other the atoms, either an ionic or covalent bond is formed, and the atoms fuse together to form a molecule.

2:Magic number, in physics, in the shell models of both atomic and nuclear structure, ... The magic numbers for atoms are 2, 10, 18, 36, 54, and 86, corresponding to the total number of electrons in filled electron shells. ... In the chemical elements of atomic number 17 to 19, for example, the chloride ion (Cl−).

Explanation:

answer 1) In chemistry and physics, a valence electron is an outer shell electron that is associated with an atom, and that can participate in the formation of a chemical bond if the outer shell is not closed; in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair.

Explanation:

I dont know the second one

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."

it means there are 3 atoms of oxygen