Transcript Hydrocarbon Names

Hydrocarbon Names
• Saturated hydrocarbons (alkanes) have
general formula CnH2n+2
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CH4 methane
C2H6 ethane
C3H8 propane
C4H10 butane
C5H12 pentane
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C6H14 hexane
C7H16 heptane
C8H18 octane
C9H20 nonane
C10H22 decane
Nonpolar bonds, only London dispersion forces
Acid Names
• All acid formulas start with H
• Binary acid names start with “hydro”,
change root ending to “ic” and add “acid”.
• HCl hydrochloric acid
• HCN hydrocyanic acid
• HBr
• HI
Acid Names
• Binary acids are only named as acids when
in water solution.
• Dry compounds are named as molecular
compounds
• Example: HCl is hydrochloric acid in water
solution, but hydrogen chloride as a free gas
Ternary acid names
• Use root of anion name followed by “-ic” or
“-ous” and “acid”
• “-ic” is used with anions ending in “-ate”
and “-ous” is used for “-ite”.
• H2SO4 sulfuric acid
• H3PO4
• HNO3
• HClO2
Exceptions to Octet rule
• Odd electron molecules (ex. NO2)
• Electron deficient molecules (ex. BF3)
• Expanded octet - only for period 3 and
higher (ex. SF6, PCl5, SO4-2)
Bond Polarity
• Bonds are polar when there is an unequal
distribution of electrons in a bond
Bond Polarity
• Polar bonds are formed when two atoms of
unequal electronegativity are bonded
• The bond has a “dipole moment” because of
the d+ and d- poles
Bond polarity
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EN difference of 0-0.4: nonpolar covalent
EN difference of >0.4-1.4: polar covalent
EN difference of >1.4: ionic bond
Greater dipole-dipole interactions means
greater mp and bp
• Example: propane (C3H8, 44amu) has
boiling point -42ºC, dimethyl ether
(CH3OCH3, 46amu) has bp -23ºC
Molecular geometry
• VSEPR = valence shell electron pair
repulsion
• Bonding and nonbonding pairs will arrange
themselves around an atom so that they are
as far from each other as possible
• 2 pairs - BeCl2
• Linear geometry, bond angle = 180º
Molecular geometry
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Three pairs - BH3, CH2O
Trigonal planar geometry, bond angle 120º
Four pairs - CH4
Tetrahedral geometry, bond angle = 109.5º
Five pairs - PCl5 (expanded octet)
Trigonal bipyramid geometry, bond angles
= 120º and 90º
Molecular geometry
• Six pairs - SF6
• Octahedral geometry, bond angles 90º
Nonbonding Pairs
• Two bonding, one nonbonding - NO2• Bent geometry (anything with two bonding
pairs and at least one nonbonding pair)
• Bond angle <120º, since nonbonding pair is
larger
Molecular geometry
• Three bonding, one nonbonding (NH3)
• Trigonal pyramidal geometry, <109.5º bond
angle
Hybridization
• Recombination of s and p orbitals to
produce equivalent bonding orbitals
• Two atoms and/or lone pairs: sp
hybridization
Hybridization
• Three atoms and/or lone pr.: sp2
• Four atoms and/or lone pr.: sp3