Online
Introductory Chemistry
|
Dr.
Walt Volland
revised July 5, 2010
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Atoms and subatomic particles
- The
three simple subatomic particles are the electron, proton and neutron.
The properties of these three are summarized here.
|
|
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relative
charge
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absolute
charge
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mass
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absolute
mass
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proton |
+1
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+1.6021773
x 10-19 C
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1.0073
amu
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1.6726
x 10-24 g
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electron |
-1
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-1.6021773
x 10-19 C
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0.0005486
amu
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9.109390
x 10-28 g
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neutron |
0 |
0
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1.0087
amu
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1.6749
x 10-24 g
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The
amu is defined as 1/12 the mass of the carbon-12 atom. The carbon-12
atom is used as the reference for atomic masses. The carbon-12 atom
is defined to have a mass of exactly 12.000000 atomic mass units, amu.
(The dalton is another name for the amu.) The masses of atoms are reported
on a relative basis. This means a magnesium-24 atom is twice as heavy
as a carbon-12 atom. You do not need to memorize the absolute values
for the charge and mass of these particles. You should know the relative
values. |
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Exercises:
Which of the following particles has the smallest mass? CLICK ON YOUR
CHOICE
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Which
of the following has a negative charge? CLICK ON YOUR CHOICE
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