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