how many electrons does P and O have in PO4^3-
Originally posted by Jiemanutz:how many electrons does P and O have in PO4^3-
Draw the Kekule/Lewis/Dot-&-Cross structural formula for the phosphate(V) ion.
Counting only the valence electrons (you go ahead and add inner shell electrons yourself), notice that phosphorus has a double bond with one oxygen atom, and single bonds with three other oxygen atoms. Notice that phosphorus has expanded its octet, and has no formal charge on it. The double bonded oxygen (with 2 bond pairs, 2 lone pairs) has a stable octet and no formal charge, while the single bonded oxygens (each with 1 bond pair, 3 lone pairs) have stable octets and a -ve formal charge (on each oxygen). Hence phosphate(V) ion is tri-negative (recall that ionic charge = sum of all formal charges).
See its Kekule structure in Wikipedia :
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