why does in ch3COONa ,negative compound come before positive element
Answers
really depends on which point you want to bring across.
NaCH3COO
N
a
C
H
3
C
O
O
This formula, being analogous to formulae like NaCl
N
a
C
l
stresses the inorganic salt view more. It shows that there is a cation (Na+
N
a
+
) and an anion (CH3COO−
C
H
3
C
O
O
−
) which form a salt crystal together much like the anion Cl−
C
l
−
would do with the same cation. Inorganic nomenclature prefers cations to be written first.
NaC2H3O2
N
a
C
2
H
3
O
2
Is basically the same except for saying ‘I don’t care how those seven atoms combine to form the anion, all I care for is what’s in there.’
CH3COONa
C
H
3
C
O
O
N
a
This one stresses a more organic-chemical point of view where it’s relevant where the cation is actually bound to within the molecule. Oftentimes, organic chemists would even write structural formulae with a bond between oxygen and sodium as if it were hydrogen. The reasoning behind this is ‘I don’t care if the structure ends up being a salt, all I need to know is that the sodium somehow connects to the carboxyl group.’
Note that you can combine the first’s and the third’s idea to give NaOOCCH3
N
a
O
O
C
C
H
3
which works, but is a lot less used than either of them.
C2H3NaO2
C
2
H
3
N
a
O
2
This is the Beilstein-type lookup formula. You just know the elemental composition of your compound and now want to look it up — you can’t know whether it’s sodium acetate or sodium hydroxyethanalate (if that name is even correct). Or maybe you just don’t care. The reasoning behind this is C
C
first, H
H
second, the remaining elements following in alphabetic order.
Finally, there are also shortened formulae. The most common (the one I actually use most) would be NaOAc
N
a
O
A
c
. Here, Ac
A
c
is an abbreviation for H3C−C=O
H
3
C
−
C
=
O
where whatever follows or precedes is bound to the carbonyl carbon. Note that this formula is not considered standard, and would need to be included in a list of abbreviations or defined otherwise if you decide to use it.