ATOMIC BOOKKEEPING
. 12 12 0
31 15 0
17 O 9 10
Atomic # mass# symbol #p+ #no #e- atom charge
12 24 12Mg
15 1516P
8 8 -2
Pertinent section of Periodic table
20 10 0
7 14 -1
Fe 30 0
17 18 19
10
26 56
35
Ne
N
Cl
10
Atomic # mass# symbol #p+ #no #e- atom charge
7
26
17
10
7 8
26
-2
Let’s go down a column left to right….
6
C 12.01
12 O
C 6
Periodic table entry for `average’ atom of C
Nuclear notation for specific isotope of C
Average atomic mass (not mass number ??)
Atomic # = p Mass #= n + p
Atomic # = p
charge
The Chemist’s element vs. the Physicist’s element
Chemist’s element Physicist’s element
Why the chemist’s C lists 12.01 and not 12
# p # n mass # caught out of 100 C atoms
6 6 99
Imagine `fishing’ out 100 atoms of Carbon from a sample of graphite (pure carbon). What would you catch ?
12
6 7 13 1
Both kinds isotopes of C act exactly the same, chemically so chemists just average the masses
Average mass = of C
99*12 + 1*13 100
= 12.01
Average mass = of each C
99*12 + 1*13 100
= 12.01
= 99 *12 + 1 * 13 100 100
Averages Written As Sums Of Fractional Contributions
=f12*12 + f13*13
fm = fraction of C atoms with mass M
Averages written as sums of % contributions
= 99 *12 + 1 * 13 100 100
Average mass of each C
=(99 % *12 + 1% * 13) 100
= (P12 *12 + P13 *13) 100
Pm = % of C atoms with mass M
Take home lesson
AV. MASS =f1*m1+f2*m2 +…..Or, from % abundances Pk and mk so:
AV. MASS =P1*m1+P2*m2 +…..100
: Average mass is computable from fractional abundances fk and mk so:
In- class exercise with mercury: Compute the average mass of Hg from abundance data
1881
3144
5720
2492
5555
1246
Sum=20057
Average mass of Hg =20057 =200.57 100
AV. MASS =P1*m1+P2*m2 +…..100
COMPOUND NAMING REVIEW (pp. 60-69)
(type 1) metals, M Non metals (NM)
(type 2), transition metals ,TM
NM
REVIEW OF BINARY NAMING CLASSES
• NM + NM
• M + NM
• TM + NM
Example Example FORMULA NAME
N2Cl4dinitrogen tetrachloride
Mg3P2magnesium phosphide
TiCl4titanium (IV) chloride
Naming classes
NM= non-metals in `blue’
Name Na2O
A. disodium monoxide
B. sodium (I) oxide
C. sodium oxide
D. sodium (II) oxide
disodium m
onoxide
sodium (I)
oxide
sodium oxide
sodium (II
) oxide
25% 25%25%25%
Name FeCl3
A. iron (I) trichloride
B. iron(III) chloride
C. iron trichloride
D. iron chloride(I)
iron (I)
trich
loride
iron(III
) chlorid
e
iron tr
ichlorid
e
iron ch
loride(I)
25% 25%25%25%
What is the formula for iron(II) nitride ?
A.FeN3
B.Fe2N3
C.Fe3N2
D.Fe2N
FeN3
Fe2N3
Fe3N2
Fe2N
25% 25%25%25%
Name P2O5
A. diphosphorus pentoxygen
B. phosphorus (V) oxide
C. phosphorus oxide
D. diphosphorus pentoxide
diphosphoru
s pento
xygen
phosphoru
s (V) o
xide
phosphoru
s oxid
e
diphosphoru
s pento
xide
25% 25%25%25%
Naming with oxyanions replacing NM
EXAMPLES OF OXYANIONS
• PO43-
formula name
phosphateOxyanion charge
-3
• SO32- sulfite -2
• NO31- nitrate -1
M + NM example(U-name-it)
BaCl2
Barium chloride
M + OXY example(models M+NM pattern)
Ba(NO3)2
Hint: Cl is -1 Hint: NO3 =nitrate is -1
Barium nitrate
TM + NM example(U-name-it)
CuO
Copper(II) oxide
TM + OXY example(models M+NM pattern)
Cu(CrO4)
Hint: O is -2 Hint: CrO4 =chromate is -2
Copper(II) chromate
In-class Board practice with OXYANIONS