1. Rubidium has 2 isotopes in nature, and the average atomic mass is 85.557 amu. Rb-85 has a relative abundance of 72.15%.
What is the relative abundance of the other isotope, Rb-87?

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.

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