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LT 2: Covalent Bonding

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Why do atoms bond? Atoms gain stability when they share electrons and form covalent bonds. This gives the atoms a FULL outer energy level. Covalent bond- chemical bond that results from sharing valence electrons in a NON- ionic compound Ex: Fluorine atoms share 2 e- to become F 2

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Why do atoms bond? Molecule- formed when two or more atoms bond covalently Ex: H 2 O, C 6 H 12 O 6 Covalent bonds are formed between two NON-metals

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Diatomic Molecules Formed when 2 atoms of each element share electrons 2 atoms molecules are more stable than the individual atoms Pneumonic to remember diatomics: HOFBrINCl Hydrogen (H 2 ) Oxygen (O 2 ) Fluorine (F 2 ) Bromine (Br 2 ) Iodine (I 2 ) Nitrogen (N 2 ) Chlorine (Cl 2 )

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Formation of F 2 Shared e- The rest are unshared e-

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Single Covalent Bond 2 e- are shared HH

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Double Covalent Bond 4 e- are shared O=O

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Triple Covalent Bond 6 e- are shared

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Bond Length/ Strength The MORE bonds present, the SHORTER the bond The SHORTER the bond length, the STRONGER the bond

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Energy and Bonds Energy changes occur when a bond between atoms in a molecule forms or breaks. Endothermic Greater energy is required to BREAK the bonds in the reactants than is released when new bonds FORM in the products Reactants > Products

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Energy and Bonds Exothermic Less energy is required to BREAK the bonds in the reactants than is released when new bonds FORM in the products Reactants < Products

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Solubility POLAR substances are soluble in POLAR solvents Ex: Sugar dissolves in H 2 O but oil does not. NON-POLAR substances are soluble in NON-POLAR solvents Ex: Oil will dissolve in CCl 4 but not water.

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State of Matter Can exist as Solids, Liquids, and Gasses at room temperature because of varied structures (depending on amount of intermolecular forces present) Solids: Sugar, candle wax Liquids: Oil, water Gas: Oxygen, carbon dioxide

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Boiling/ Melting Points Weaker forces of attraction than ionic compounds so melting points are lower than those of ionic compounds Boiling points are also lower than those of ionic compounds Melting points and boiling points are varied depending on number and type of intermolecular forces are present

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Conductivity Covalent compounds are not made of ions so when they dissolve, they do not allow a current to flow.