Transcript Atomic Structure Review - East Pennsboro High School

Have a
Periodic
Table & a
calculator
per group!
The
mass number
true
2.75 g Al
1 mol Al
27 g Al
= 0.102 mol Al
6.02X1023
Al atoms
Protons
& neutrons
The
Nuclear Model
positive
The
Plum Pudding Model
0.75 mol Na 6.02x1023 atoms Na
1 mol Na
= 4.5x1023 mol Na
proton
grams
amu
(atomic mass unit)
2.5x1015 atoms of Au
1 mol Au
6.02x1023 atoms Au
= 4.0x10-9 mol Au
Neutrons
J.J.
Thomson
Ernest
Rutherford

John Dalton
Plum
Pudding Model
All matter is composed of atoms
Atoms can’t be divided, created or
destroyed
Atoms of different elements
combine in simple whole-number
ratios to form compounds
Atoms are identical in mass
Atoms can be combined, separated
or rearranged


NO!!
Atoms of the same element
can have different masses –
isotopes
Atoms are divisible – Nuclear
chem.
Atoms can be changed from
one element to anotherNuclear chem.


James Chadwick

J.J. Thomson
Theory

Cathode Ray Tube

8

Mass Number
Consisted
of a cloud of
evenly distributed positive
charge with the negative
electrons embedded
randomly in it.

one mole = molar mass
The
Plum Pudding Model

56
Fe
26
0.25 mol Pb 207 g Pb
1 mol Pb
= 51.75 g Pb
Cathode rays were
attracted to the positive
charge

Cathode rays have a
NEGATIVE charge


beam of electrons

7

Democritus
Atoms
space
are mostly empty
the atom has a small dense
positive region that caused
the positive particles to
bounce back…..the nucleus

An atom makes up an
element.
An element can’t be broken
down.

positive

one mole = 6.02 X 1023 atoms
neutral

MOLE!!
Scientific
Law

NUCLEUS
Suggested
that the electrons
travel around the positively
charged nucleus.
 Difference is that the positive
charges are NOT spread out like
in Thomson’s Plum Pudding
Model.
NEUTRONS!
The number of protons and
electrons are the same!

Their
mass number

Carbon - 14

11

6

Molar Mass

the mass number
Nuclear
Atomic
Symbol
Number
Protons
Mass Number
13
N
7
7
7
20
F
K
19
6
Electrons
7
9
9
20
11
9
19
19
40
21
19
9
40
13
Neutrons

Average atomic mass

1 atomic mass unit (amu)
negative