Worksheet
Unit 3 – Subatomic Particles, Atomic and Mass Number
Name: _______________________________________ Date: _____________________ Period: ______
Subatomic particles, Atomic Number & Mass Number Relationships
Learning Goals/Objective:
•
•
•
I can discuss atoms in terms of their number of electrons, neutrons, and protons and define the
terms of atomic number and mass number.
I can use mass number and atomic number to describe various isotopes.
I can calculate the average atomic mass of an element.
Electrons = -1 charge
Protons = + 1 Charge
Neutrons = 0 Charge
In a neutral atom, the # of electrons = the # of protons.
Atomic Number (AN)
a) Every atom has protons and neutrons in the nucleus, with electrons orbiting the nucleus.
b) All atoms of the same element have the same number of protons.
c) The Atomic number (Z) is the number of protons
Mass Number (MN)
a) Mass number is the total number of particles in the nucleus. This is a whole number and
may be different than the Atomic Mass seen on the periodic table.
b) Mass Number (MN)
# of protons + # of neutrons
OR
# of neutrons = MN - # of protons
c) Generally, the mass number for each element is the element’s atomic mass rounded to the
nearest whole number. This will be different when we are looking at isotopes.
Element Naming/Notation:
1) Name
Element – Mass Number
2) Symbol
MN
AN
Symbol
3)
Example:
Name: Sulfur – 32
BRYAN WALTERS
Symbol:
32
16𝑆
1
Worksheet
Unit 3 – Subatomic Particles, Atomic and Mass Number
The Element Table – for this exercise, consider the atoms to be neutral. You will need a periodic table.
Name
Symbol
Atomic
Number
(AN)
Name - MN
𝑀𝑁
𝐴𝑁𝑆𝑦𝑚𝑏𝑜𝑙
AN =
# of P
# of
Protons
(P)
# of
Neutrons
(N)
Mass
Number
(MN)
# of
Electrons
(E)
#P = AN or
MN - #N
#N =
MN - #P
MN =
#P + # N
E = #P
in neutral
atoms
Hydrogen -1
4
2He
3
4
4
9
6
11
12
7
6
7
Oxygen -16
19
9F
10
10
44
BRYAN WALTERS
101
2
Worksheet
Unit 3 – Subatomic Particles, Atomic and Mass Number
Name
Symbol
Atomic
Number
(AN)
# of
Protons
(P)
# of
Neutrons
(N)
Mass
Number
(MN)
# of
Electrons
(E)
Name - MN
𝑀𝑁
𝐴𝑁𝑆𝑦𝑚𝑏𝑜𝑙
AN =
# of P
#P = AN or
MN - #N
#N =
MN - #P
MN =
#P + # N
E = #P
in neutral
atoms
Tin – 119
64
29Cu
26
30
31
70
54
96
133
55
Radon – 222
190
76Os
77
92
54
238
125
207
91
BRYAN WALTERS
40
3
Worksheet
Unit 3 – Subatomic Particles, Atomic and Mass Number
Name
Symbol
Atomic
Number
(AN)
# of
Protons
(P)
# of
Neutrons
(N)
Mass
Number
(MN)
# of
Electrons
(E)
Name - MN
𝑀𝑁
𝐴𝑁𝑆𝑦𝑚𝑏𝑜𝑙
AN =
# of P
#P = AN or
MN - #N
#N =
MN - #P
MN =
#P + # N
E = #P
in neutral
atoms
Cobalt - 60
47
108
40
19K
65
31
23
30
28
51
27
13Al
45
80
Iron - 56
16
16
Sodium - 23
35
17Cl
BRYAN WALTERS
4