Hello!
When finding the chemical formula of a compound, we will need to find the charges of each element/bond.
Looking at our period table, sodium has a +1 charge, written as Na 1+, and sulfate has a charge of -2, and it is written as SO4 2-.
Now, we need to make the charges equivalent. To do this, we need to "criss-cross" the charges. This means that sodium will need to additional atoms to make the charges equal, and sulfate will need one.
Therefore, the chemical formula for sodium sulfate is: Na2SO4.
Atoms return to their ground state by emitting a photon of light.
Here is the answer for the three of them
<span>N20 = 16 e-
</span><span>SeCl2 =20
</span><span>PBr3 = 26
Remember that t</span><span>o find the valence electrons in an atom you need to identify what group the element is in. An element in group 1A has 1 valence electron. If the element is in group 2A, then it has two valence electrons.</span>
