Download Atomic Components


Other Discoveries
Electron Charge (-1)
 Protons

 Mass
is 1836 times an electron
 Charge is (+1)

Neutrons
 James
Chadwick, 1932
 No Charge
Bohr Model of the Atom

How are electrons
arranged around the
nucleus so that they
do not fall in?
Planetary Model
e Electrons are in
circular “orbits” around
nucleus
 Would eventually
collapse

e-
e-
e+
o o+ o +
+ o +o
+ oo
o
e-
e-
In Proportion
If the nucleus was the size of a pen point
 The first electron would be 137 m away

Bohr Model of the Atom

How are electrons
arranged around the
nucleus so that they
do not fall in?
Planetary Model
e Electrons are in
circular “orbits” around
nucleus
 Would eventually
collapse

e-
e-
e+
o o+ o +
+ o +o
+ oo
o
e-
e-
Atomic Components

Electron (e-)




Proton (p+)




Negative charge (-1)
Found outside nucleus
Very tiny (9.110 x 10-28 g or 0.000549 AMU)
Positive charge (+1)
Found in nucleus
Much larger (1.673 x 10-24g or 1.0073 AMU)
Atomic
Mass
Units
Neutron (no)



Neutral charge
Found in nucleus
Slightly larger than a proton (1.675 x 10-24g or 1.0087 AMU)
Isotopes

Atomic Number
Number of protons
 Gives identity (always the same)


Mass Number
Number of protons and neutrons
 May vary for the same atom type


Isotopes – atoms with the same number of
protons and a different number of neutrons
10 p+
10 no
+
11 no
 Neon-21 10 p
Mass 12 no
 Neon-22 10 p+
Number
 Neon-20

Number of p+ = number of e- (neutral)
 Carbon-12
Mass
Number
6 p+
12
6
6 e-
C
6no
Symbol
Atomic
Number
 Carbon-14
6 p+
14
6
6 e-
C
8no (Radioactive)
Practice:
82: 29
a. 244
94Pu
b. 241
95Am
c. 227
89Ac
d. 133
55Cs
e. 193
77Ir
f. 56
25Mn

94 p+
95 p+
89 p+
55 p+
77 p+
25 p+
150 n0
146 n0
138 n0
78 n0
116 n0
31 n0
94 e95 e89 e55 e77 e25 e-
28: 30
Name
Symbol Atomic Mass
Neutrons
Number Number
Sodium-23
Nitrogen-15
11
23
15
7N
136
56Ba
Lithium-9
Boron-11
6
5
11