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Atom Do Now
You may work alone or with a partner:
On a piece of paper write down everything you know about atoms
Then write down one thing you would like to know or learn about atoms
Make sure your name(s) are on the paper and hand it in
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March 01, 2010
Atom ­ basic unit of matter. ­ each different atom represents a
different element
­ 109 natural elements found on the periodic table
­ each atom/element has its own specific physical & chemical properties
­ composed of 3 subatomic particles: protons, electron, neutrons
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An electron carries a negative charge and has almost no mass. March 01, 2010
­
Electrons can be found orbiting the nucleus of an atom.
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Protons and neutrons exist in the nucleus of the atom.
Protons have a positive charge and neutrons have no charge.
1
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1
+
Both protons and neutrons have a mass of 1.
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Complete the table below
Click here
for the
answer
Particle
­
Electron
+
Proton
Charge
Mass
Neutron
+
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­
1
0
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In the periodic table, the element called oxygen is represented in this way.
smaller
The number at the bottom is the number. It is the number of protons in one atom of the element.
16
atomic 8
O
p + = 8
What is the atomic number of the elements on the next page?
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This is the element sodium . The number at larger
the top is the atomic mass . It is the total number of protons and neutrons in one atom of the element.
March 01, 2010
23
Na
11
How many protons and neutrons does sodium have?
from atomic number, sodium has 11 protons. Since the atomic mass is 23, 23 ­ 11 = 12 neutrons
Sodium has 11 protons and 12 neutrons (atomic mass = the number of protons plus the number of neutrons)
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Atoms are neutral
(the total charge cancels to zero)
Therefore... in an atom
# of electrons = # of protons
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The following pages are answers to the tasks in the lesson activity.
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Complete the table below
Click here
to go back
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Particle
Charge
Mass
­
Electron
­
0
+
Proton
+
1
Neutron
0
1
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