Explain how dmitri mendeleev arranged his periodic table. how was he able to make predictions about the blanks that he left in the table?

He predicted them by the chemical similarities.

the answer would be a

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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