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How to Write the Formula for Potassium oxide (K2O)



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to write the formula for potassium oxide

we go to the periodic table we look up

potassium which is K and then for oxide

we're looking for oxygen on the periodic

table that's o and because we have a

metal here the potassium and a nonmetal

of the oxygen we have an ionic compound

and with ionic compounds we need to

balance the charges so we look at the

periodic table and we see that potassium

has a +1 charge and oxygen has a minus 2

that means the net charge is not zero

the plus 1 and the minus 2 when we add

them up they don't equal zero so we need

to change the subscripts here in order

to make them balance what we can do is

we see if we put a 2 right here 2 times

plus 1 that gives us a plus 2 that will

cancel out our minus 2 and that will

give us a formula of k2o for potassium

oxide there's a quick way we can check

our work it's called the crisscross

method in the crisscross method we take

the to move it down here to the

subscript to the potassium then we move

the one over here but we don't write one

it's assumed that it's there we remove

our charges and we get the same answer

k2o

so the correct formula for potassium

oxide is k 2o this is dr. B and thanks

for watching