List four greenhouse gases in the atmosphere. for each gas, describe its prevalence in the atmosphere, its natural sources, its human-induced sources, and how its concentration in the atmosphere might be changing.

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!

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