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2-8-8 Rule Electrons orbit the nucleus in energy levels within the electron cloud
The 1st energy level holds 2 electrons
The 2nd and 3rd energy levels holds 8 electrons
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Valence Electron
Valence electrons: electrons in the last shell or energy level of an atom.
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Last energy level: Level 3
Last energy level: Level 3
So count the electrons in the last energy level
So count the electrons in the last energy level
6 Valence Electrons!6 Valence Electrons!
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How many valence electrons are in this atom?
How many valence electrons are in this atom?
33Valence Electrons
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55
How many valence electrons are in this atom?
How many valence electrons are in this atom?
55Valence Electrons
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How many valence electrons are in this atom?
How many valence electrons are in this atom?
11Valence Electrons
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How many valence electrons are in this atom?
How many valence electrons are in this atom?
22Valence Electrons
Happy Atoms
“Happy" atoms are stable atoms
Atoms are stable when their outermost energy levels (shells) are full
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StableStable
StableStable
StableStable
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Is this atom stable?Is this atom stable?
YES!YES!
Is this atom stable?Is this atom stable?
NO!NO!
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SadAtoms
Sad atoms are not stable When an atom's outermost shell
is not complete/full it is not stable.
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Is this atom unstable?Is this atom unstable?
NO!NO!
Is this atom unstable?Is this atom unstable?
YES!YES!
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SadAtoms
Atoms become stable by bonding (joining) with other elements. Bonded atoms are called molecules. A covalent bond is one where
atoms share electrons. An ionic bond is one where
electrons are either given or taken, not shared.
