Since helium has an atomic number of 2 and an atomic weight of 4, we know it must contain 2, 4, or 6 neutrons

pie chart because it is in percents ( % )

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

if you need further assistance, let me know: )

~ trueboss72

it takes on an electronical energy