Name the Three Subatomic
Particles found in an atom.
Proton P+
Electron eNeutron N
Properties of Subatomic Particles
Particle
Symbol
Electron
e- -1
0
0.0005486
9.109 x10
-28
Proton
p+ +1
1
1.007276
1.673x 10
-24
1.675x 10
-24
Neutron
n
Charge
0
Mass Relative mass
#
(a.m.u.)
1
1.008665
Actual mass
(grams)
The total number of
protons in an atom of an
element can never change
without changing the
identity of the element.
Determining the number of
protons, electrons and neutrons.
The Atomic number equals the # of protons (p+)
Atomic #
Atomic Mass
6
C
In a neutral atom
the # of protons =
the # of electrons
12.01
The Mass # is the atomic mass rounded to the nearest whole #
The # of n = Mass # - Atomic #
Sub-Atomic Particles
How many Protons, electrons
and neutrons are in an atom of
Aluminum ?
14 Neutrons
(Mass# -At. #)
(27-13)
13
Al
26.981538
13
protons
13
electrons
Calculate number of Sub-atomic
particles for :
Element
Protons Electrons
Boron
5
5
Nitrogen
7
7
Chlorine
17
17
Argon
18
18
Iodine
53
53
Chlorine ion with a
17
18
-1 charge
Sodium Ion with a
11
10
+1 charge
Neutrons
6
7
18
22
74
18
12
In an atom the
number of protons
never changes!
HOWEVER! . . .
The total number of
Neutrons can change!
Isotopes are atoms with
the same number of
protons but different
numbers of neutrons
In a neutral atom the total
number of protons equals the
total number of electrons!
HOWEVER! . . .
The total number of
electrons can change!
Ions
Ions are charged atoms that have a different
number of electrons than protons. There are
two types of ions.
Cations are positively charged atoms where
the number of electrons is less than the
protons.
Anions are negatively charged atoms where
the number of electrons is more than
the protons.
Cation vs. Anion
Cations will lose electrons
electron
neutron
proton
The atom becomes
positive
e-
Cation vs. Anion
Anions will gain electrons
electron
neutron
proton
e
The atom becomes negative
Locating Subatomic
particles
How do you show protons,
neutrons and electrons in their
proper location?
Draw Bohr Diagrams
Diagramming the Atom
The Bohr diagram shows the location and
numbers of the electrons and nucleons.
1
2
3
4
5
6
7
6
7
The number of
Energy levels
can be
determined by
looking at the
period that the
element is
located in the
periodic table.
Diagramming the Atom
The Valence e- can be determined by the group number.
Unfortunately the transitional elements must be skipped
due to their ability to change their valance e- number.
1e- 2e-
3e- 4e- 5e- 6e- 7e- 8e-
Skip transitional
metals (1-6 e-)
Valence e- are the
electrons found on
the outermost
energy level. They
are involved in
chemical reactions
The Bohr Diagram
Step 1  Determine # of p, n,& eStep 2  Determine # of Energy levels
Step 3  Determine # of Valence eStep 4  Draw nucleus and shells, Place
the Valence e- on outside shell 1st.
Place remaining electrons starting
on the inside shell and working
outward using 2n2 as a guide.
Bohr Diagram of Carbon-12
n
e-
NRG
level
Valence
6
6
6
2
4
6
8
6
2
4
Element
p+
Carbon-12
Carbon-14
6p
6n
6p
8n
2e-
4e-
2e-
4e-
e-
Complete Bohr Diagrams
for elements 1-20
Elements 1-11
1p
0n
3p
4n
2p
2n
2e- 1e-
2e-
1e-
4p
5n
5p
6n
2e- 2e-
6p
6n
2e- 3e-
2e- 4e-
-
7p
7n
2e-
5e-
2e-
6e-
11p
12n
10p
10n
9p
10n
8p
8n
2e- 7e-
2e- 8e-
2e- 8e- 1e-