Vocabulary

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Vocabulary

• ATOM-An atom is the smallest unit that maintains
  the characteristics of an element
• Nucleus- The center of the atom, contains protons
  and neutrons
• Electron Cloud Region surrounding the nucleus
  containing the electrons
• ELEMENT- A chemical substance that is composed of
  atoms with the same number of protons in the
  nucleus

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The Atom
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The Atom
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Protons
Neutrons
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• http//www.geocities.com/Yosemite/Rapids/1111/adam
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The Nucleus
Proton-A positively charged sub-atomic particle
(). Atomic Mass1 amu The number of protons is
the same as the atomic number
The atomic mass
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The Nucleus
Neutrons A sub-atomic particle in the
nucleus --Has a mass equal to 1 atomic mass
unit --Neutron do not have a charge (0) To
calculate the number of neutrons in an element

• The atomic mass
• The atomic number
• The number of neutrons

The atomic mass
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The Atom
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The Electron Cloud

• Electrons-
• The number of electrons equals the number of
  protons
• Sub-atomic particle with a negative charge (-)
• Mass of an electron is negligible
• Electrons behave as if in a 3-D orbit
• Valence Electrons
• The outer most electrons
• Valence electrons are responsible for bonding

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Bohr Model

• The first shell can have
• 2 electrons
• The second shell can
• have 8 electrons

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Shells and the Electron Cloud
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Periodic Table

• Groups- Arranged by the number of valence
  electrons
• Each group has similar bonding properties
• Periods-Arranged by increasing atomic weight
• Periods have the same number of shells

Example Group 11 valence electron Group 22
valence electrons Group 33 valence electrons
Example Period 11 valence shell Period 22
valence shells Period 33 valence shells
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Periodic Table
Periods go across on the periodic table Periods
have the same number of shells
1
2
3
4
5
6
7
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Periodic Table
Groups go down on the periodic table Elements in
the same group, have the same number of valence
electrons
1
2
3
4
5
6
8
7
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Lets look at a few elements
Hydrogen
1 Proton 1 electron
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Lets look at a few elements
Helium
2protons 2neutrons 2electrons
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Lets look at a few elements
Lithium
3protons 4neutrons 3electrons
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Lets look at a few elements
9protons 10neutrons 9electrons
Fluorine
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Lets look at a few elements
18protons 22neutrons 18electrons
Argon
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