Ch. 19 - Atomic Structure
I. Subatomic Particles
(p. 578-583)
II. The Periodic Table
(p. 588- 596)
Subatomic Particles
ATOM
ATOM
NUCLEUS
NUCLEUS
ELECTRONS
ELECTRONS
PROTONS
PROTONS
NEUTRONS
NEUTRONS
POSITIVE
CHARGE
NEUTRAL
CHARGE
NEGATIVE
CHARGE
NEGATIVE CHARGE
equal in a
Atomic
Most Number
of the atom’s mass.
neutral atom
equals the # of...
QUARKS
Subatomic Particles
(Parts of the Atom)
Particle Symbol Charge
Electron
Proton
Neutron
ep+
n0
+
0
Relative
Mass
0 amu
1 amu
1 amu
Location of Subatomic Particles
Electron (-)
Nucleus
Proton (+)
Neutron
Atoms are building blocks of
elements.
Each element is made of only
one type of atom.
Example: Aluminum is made
only of aluminum atoms.
Each element’s atoms are
different from atoms of other
elements.
Example: Aluminum’s atoms are
different from copper’s atoms.
Atomic Number
The number of
protons in the atom.
(If the atom is neutral,
it is also the number
of electrons.)
Atomic Number on the
Periodic Table
Atomic Number
Symbol
11
Na
All atoms of an element have the
same number of protons!
11 protons
Sodium
11
Na
Learning Check
State the number of protons (or electrons) for
atoms of each of the following:
1. Nitrogen
A) 5
B) 7
C) 14
2. Sulfur
A) 32
B) 16
C) 6
B) 81
C) 56
3. Barium
A) 137
Mass Number
Counts the number
of
protons plus neutrons
in an atom,
so to find the number of neutrons you
simply use this formula:
Mass # - Atomic # = # of neutrons
Atomic Symbols
 Show the mass number and atomic number
 Give the symbol of the element
Atomic Number
11
Na
Mass Number
23
Number of Electrons
An atom is neutral
The net charge is zero
Number of protons =
Number of electrons
Atomic number = Number
of electrons
Subatomic Particles in
Some Atoms
8
15
30
O
P
Zn
16
31
65
8 p+
15 p+
30 p+
8 e-
15 e-
30 e-
8n
16 n
35 n
Drawing Atomic Models
 The first electron shell/level/cloud can
hold 2 electrons
 The second electron shell/level/cloud
can hold 8 electrons
 The third electron shell/level/cloud
can hold 18 electrons
 The neutrons and protons are in the
nucleus (center)
Let’s draw a model for sodium (Na)
 How many protons
does it have?
• 11 (same as atomic
number)
 How many neutrons?
• 12 (atomic mass atomic number = 23 11 = 12)
 How many electrons?
• 11 (same as # of
protons)
11
Na
23
Where do we put this stuff?
11 protons, 12 neutrons,
11 electrons
Protons and neutrons go
in the nucleus
Electrons go in the
orbitals/shells/clouds
How many electrons fit in the third
first
second
shell?
e- e-
e-
e-
e-
11 p+
12 n0
e-
e-
e-
e-
Protons
and
e- neutrons
go in the
nucleus
-
e
Examples of 3-d Bohr Models
 Visionlearning
The Elements Song
Lewis Dot Structure
•
• C•
•
What does this
symbol mean?
•
• C•
•
Dots tell
you
valence
electrons
Carbon
Valence Electrons?
•
• C•
•
Valence electrons
are electrons in
the outermost
shell of an atom.
They are involved
in forming bonds
with other
elements.
How do you figure out
valence electrons?
Protons?
6
6 (same as atomic number)
C
12
Neutrons?
6 (atomic mass - atomic
number)
Electrons?
6 (same as atomic number)
So we know carbon has
6 electrons…now what?
e-
ee-
6p+
6n
e-
The first shell holds
2.
Now 4 are left.
e- e-They go in the
second shell.
How many are in the
outermost shell?
4!
4 valence
electrons=4 dots!
•
• C•
•
How to draw your
dots…
•
•
••Cl••
•
6
2
3
1
7
5
4
Chlorine has 7
valence
electrons. First
put dots on
each side
before you
double up.
An Easy Trick!
To figure out how many dots to draw
1
2
(1)3 (1)4 (1)5 (1)6 (1)7 (1)8
Exception!
If an element has a full outermost
shell, that means it does not
react with anything.
•
•
••Ne••
••
Which
elements
have full
outermost
shells?
Now you try…
1.Lithium
Li •
•
2.Nitrogen
N• ••
•
•
Ca •
3.Calcium
••
4.Oxygen
5.Fluorine
O
•
•
••
•
•
F• ••
•
•
Atoms Family Album
Click on the Light Bulb to
See the Atoms Family Album