The mass of 6.022x1023 barium atoms is 137.3g. What is the mass, in grams, of one barium atom?

137

Explanation:

6.022x1023 is one mole. to work out the mass you do number of moles multiplied my Mr (which is 137)

1 mole x 137 = 137g

i just learnt this recently but i need to look through my notes again

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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