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Atoms
- •protons: positive charge
- •# of protons = atomic number
- •found in nucleus
- •neutrons: no charge
- •protons+ neutrons = atomic weight
- •found in nucleus
- •electrons: negative charge
- •circulate in orbitals
- •determinereactivity
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Molecules
- Two or more atoms bound together
- Subscripts denote number of atoms
- –CO2 (carbon dioxide)
- –H2O (water)
- –C6H12O6 (sugar)
- •Bond types: ionic, covalent, hydrogen
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Ionic Bonds
- bonds between ions
- –charged atoms or molecules•may be positive (+) or negative (-)
- –extra electrons = negative charge
- –missing electrons = positive charge
- •some common ions
- –Na+, Cl-, K+, HCO3-, PO43-
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Covelant Bonds
- electrons are shared
- –single bond (2 electrons shared)
- –double bond (4 electrons shared)
- –triple bond (6 electrons shared)
- much stronger than ionic bonds
- –lots of energy stored in the bonds
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