Selenium, an element used in the manufacture of solar energy devices, forms an oxide that contains only one atom of selenium (SeOx) and is 37.8% oxygen by mass. What is the molecular formula of the oxide? (Hint: find “x”)

The molecular formula of the compound will be

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:

......(1)

Let the mass of the compound be 100 g

Given values:

% of O = 37.8%

% of Se = [100 - 37.8] = 62.2%

Mass of O = 37.8 g

Mass of Se = 62.2 g

We know:

Molar mass of Se = 79 g/mol

Molar mass of O = 16 g/mol

Putting values in equation 1, we get:

Calculating the mole fraction of each element by dividing the calculated moles by  the least calculated number of moles that is 0.787 moles

Taking the mole ratio as their subscripts.

The ratio of Se : O = 1 : 3

Hence, the molecular formula of the compound will be

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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