Cumberland High School · Chemistry
Name ________________________________
Period ________ Date ___ /___ /___
1 · Atomic Particles
PRACTICE 1: DISTINGUISHING AMONG ATOMS (Neutral Atoms)
DIRECTIONS: Fill in the missing information below.
8
_______________
0
_______________
Oxygen
15.9999
_______________
_______________
30
5
Zn
B
_________
65.39
Atomic #
Atomic number equals
the number of
_____________ or _____________
Mass number equals
the number of
_____________ + _____________
=
______________
_________
10.81
Atomic #
=
______________
Average Atomic Mass =______________
Average Atomic Mass = ______________
# of Protons
=
______________
# of Protons
=
______________
# of Neutrons
=
______________
# of Neutrons
=
______________
# of Electrons
=
______________
# of Electrons
=
______________
79
25
Au
Mn
_________
196.967
Atomic #
=
______________
_________
54.938
Atomic #
=
______________
Average Atomic Mass = ______________
Average Atomic Mass = ______________
# of Protons
=
______________
# of Protons
=
______________
# of Neutrons
=
______________
# of Neutrons
=
______________
# of Electrons
=
______________
# of Electrons
=
______________
DIRECTIONS: Complete the following chart. Assume all atoms to be neutral.
Name
Symbol
p+
e-
n0
Atomic
Number
Mass
Number
Selenium-79
14
28
8
17
1
8
9
7
10
19
39
27
59
33
75
39
89
Cumberland High School · Chemistry
Name ________________________________
Period ________ Date ___ /___ /___
1 · Atomic Particles
PRACTICE 2: DISTINGUISHING AMONG ATOMS (Neutral Atoms & Ions)
An atom is made up of protons and neutrons (both found in the nucleus) and electrons (in the surrounding
electron cloud). The atomic number is equal to the number of protons. The mass number is equal to the number of
protons plus neutrons. In a neutral atom, the number of protons equals the number of electrons. The charge on an
ion indicates an imbalance between protons and electrons. Too many electrons produces a negative charge; too
few a positive charge.
This structure can be written as part of a chemical symbol.
Example:
mass number
charge
atomic
number
7 protons
8 neutrons (15 - 7)
4 electrons
DIRECTIONS: Complete the following chart.
Element/Ion
Atomic
Number
Atomic
Mass
Mass
Number
Protons
Neutrons
Electrons
Cumberland High School · Chemistry
Name ________________________________
Period ________ Date ___ /___ /___
1 · Atomic Particles
PRACTICE 3: DISTINGUISHING AMONG ATOMS (Neutral Atoms and Ions)
Directions: Fill in the blanks for the elements in this chart.
Element
Nuclear
Symbol
Number
of Protons
Number of
Neutrons
Number of
Electrons
Mass
Number
Atomic
Number
130
54
68
+2
30 Zn
Sodium-
12
16
18
Nickel75
-3
33 As
Copper-
27
1
35
0
0
36
Tungsten-
184
197
79 Au
1
2
18
37
19
Unless otherwise indicated, assume above elements to be neutral atoms.
NOTE: Mass Numbers of the most common isotope of an atom may be estimated using the
Average Atomic Mass from the PT and rounding to the nearest whole number