Atoms have charges. There are two kinds of
charges. There are positive (+) charges and negative (-)
charges. Scientists have discovered that some parts of an atom have
positive charges and other parts have negative charges.
PROTONS - have positive charges (+)
ELECTRONS - have negative charges (-)
NEUTRONS - have no charges. They
are neutral.
An atom has the same number of protons and
electrons. Notice on the diagram below there are 2 protons and
2 electrons.
The number of neutrons and protons of an
atom is called its atomic weight (mass).
Each PROTON is given a weight of one.
Each NEUTRON is given a weight of one.
Here's an example:
Name of Element
Number of Protons
Number of Neutrons
Atomic Weight
cobalt
27
32
59
Practice finding the atomic weight of each
of the elements listed below. Remember the atomic weight equals the
sum of the protons and neutrons.
Name of Element
Number of Protons
Number of Neutrons
Atomic Weight
zinc
30
35
krypton
36
48
potassium
19
20
silver
47
61
lead
82
125
oxygen
8
8
hydrogen
1
0
calcium
20
20
Directions: Answer the questions about atomic
weight.
1. A
has a positive charge.
2. An
has a negative charge.
3. A
has no charge.
4. The number of
and protons of an atom is called its atomic weight (mass).
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