1. Molecular Formulas Organics Nomenclature

2. Molecular Bonding
Molecule – a neutral group of atoms joined together by covalent bonds.
Covalent bond – atoms joined and held together by sharing electrons.
Molecular compound – a compound composed of molecules.
Ex.

3. Molecular Bonding
Diatomic molecule – a molecule consisting of 2 atoms. Ex. Oxygen (O2)
Seven elements exist as diatomic molecules: H2, O2, N2, F2, Br2, I2, Cl2
This relates only to these elements as isolated, neutral atoms.

4. Difference between ionic and molecular

5. Ethane, a component of natural gas, is also a molecular compound.

6. What information does a molecular formula provide?
Molecular formula – chemical formula of a molecular compound
A molecular formula shows how many atoms of each element a molecule contains
A subscript written after the symbol indicates the number of atoms of each element in the molecule
Ex. N2H2 CH4
SUBSCRIPT
SUBSCRIPT

7. Formulas of some molecular compounds

8. Molecular Formula

9. Were you paying attention?
A molecular formula shows
how many atoms of each element a molecule contains.
a molecule's structure.
which atoms are bonded together.
how atoms are arranged in space.

10. Octet Rule in Covalent Bonding
In covalent bonds, electron sharing usually occurs so that atoms attain the electron configuration of noble gases
Octet Rule – in forming compounds, atoms tend to achieve the electron configuration of a noble gas
Noble gases: 8 e-’s in its highest occupied energy level (ns2np6) = stable, inert, unreactive

11. Valence Electrons
Valence electrons are the only electrons used in chemical bonds
Group # distinguishes the # of valence e-’s

12. Single Covalent
Two atoms held together by sharing a pair of electrons are joined by a single covalent bond.

13. Single Covalent

14. Double Covalent Bonds
Double covalent bond - a bond that involves two shared pairs of electrons.

15. Triple Covalent Bond
Triple Covalent Bond – a bond formed by sharing three pairs of electrons

16. Were you paying attention?
In covalent bonding, atoms attain the configuration of noble gases by
losing electrons.
gaining electrons.
transferring electrons.
sharing electrons.

17. 2. Electron dot diagrams are superior to molecular formulas in that they
show which electrons are shared.
indicate the number of each kind of atom in the molecule.
show the arrangement of atoms in the molecule.
are easier to write or draw.

18. 3. Which of the following molecules would contain a bond formed when atoms share three pairs of electrons?
Se2
As2
Br2
Te2

19. Bonding Theories
VSEPR Theory – the repulsion between electron pairs causes molecular shapes to adjust so that the valence-electron pairs stay as far apart as possible

20. Nine Bonding Molecular Shapes

21. Organics - Hydrocarbons
Hydrocarbons – simplest organic compounds that contain only carbon & hydrogen
Ex. methane (CH4) & ethane (C2H6)
One carbon atom can form a single covalent bond with four hydrogen atoms.
Principle of organics: carbon has 4 valence e-’s; will always form 4 covalent bonds

22. Hydrocarbons

23. Hydrocarbon - Alkanes
Alkane – hydrocarbons with only single covalent bonds.
Arranged in a straight chain or in a chain that has branches.
CnH2n+2  results in the highest ratio of H/C ratio for a stable hydrocarbon.
Saturated hydrocarbons – H/C ratio is at a max.

24. Straight Chain Alkanes
Naming: every alkane ends with suffix –ane.
Straight chain carbons with 1-4 carbons same common name and official name
Prefixes: pent- for 5, hex- for 6, hept- for 7, oct- for 8…

26. Branched-Chain Alkanes
Substituent - an atom or group of atoms that can take the place of a hydrogen atom on a parent hydrocarbon molecule.

27. A hydrocarbon substituent is called an alkyl group.
Alkyl group can be 1 carbon or several carbons long.
Alkyl groups naming: remove the -ane ending from parent hydrocarbon & add -yl.
Ex. (CH3 –) methyl group
(CH3CH2 –) ethyl group
(CH3CH2CH2 –) propyl group
An alkane with one or more alkyl groups is called a branched-chain alkane.

28. Naming Branched-Chain Alkanes
Name this compound using the IUPAC system. Notice that the longest chain is not written in a straight line. 1 2 3
3,3 dimethylhexane 4 5 6

29. Name these compounds according to the IUPAC system
1.) 5 4 3 2 1 6
3-ethylhexane
2.) 4 3 2 1
2-methylbutane

30. Name these compounds according to the IUPAC system
3.) 1 2 3 4 5
2,2,4-trimethylpentane
Draw a structural formula for 2,3-dimethylhexane
CH3
CH3
CH3 – CH – CH – CH2 – CH2 – CH3

31. Were you paying attention?
Choose the correct words for the spaces. Because carbon has ______ valence electrons, it can form ______________ bonds.
four, four covalent
four, four ionic
six, six covalent
six, four or fewer covalent

32. Alkanes are hydrocarbons that contain only ___________ bonds.
carbon-carbon
single covalent
carbon-hydrogen
ionic

33. Hydrocarbons - Alkenes
Alkenes – hydrocarbons that contain one or more carbon-carbon double covalent bonds.
CnH2n  unsaturated hydrocarbon.
Naming: same IUPAC rules, ending in –ene.
CnH2n is the general formula for predicting a open chain alkene. n= the # of C atoms

34. Hydrocarbons - Alkynes
Alkynes – hydrocarbons that contain one or more carbon-carbon triple covalent bonds.
Name
Chemical Formula
Ethyne
C2H2
Propyne
C3H4
Butyne
C4H6
Pentyne
C5H8
Hexyne
C6H10
Heptyne
C7H12
Octyne
C8H14
Nonyne
C9H16
Decyne
C10H18
CnH2n-2  unsaturated hydrocarbon.
Naming: same IUPAC rules, ending in -yne

35. Were you paying attention?
What is the correct name for a compound with a C-C-C=C-C carbon skeleton?
3-pentyne
2-pentene
3-pentene
4-pentene

36. 2. Which of the following substances is an alkyne?

37. Isomers
Isomers – compounds that have the same molecular formula but different molecular structures
Structural isomers differ in physical properties such as boiling point and melting point. They also have different chemical reactivities.

39. Isomers of C6H14
Q. Is C6H14 an alkane, alkene, or alkyne? (Think of general formulas used to predict the molecular formula of these compounds)

40. Stereoisomers
Stereoisomers – molecules in which the atoms are joined in the same order, but the positions of the atoms in space are different.
2 types of stereoisomers
1.) geometric isomers
2.) optical isomers

41. Geometric isomers
Geometric isomers – atoms joined in the same order, but differ in the orientation of groups around a double bond.
Cis configuration - the methyl groups are on the same side of the double bond
Trans configuration - the methyl groups are on opposite sides of the double bond

42. Geometric Isomers
There is a trans and a cis configuration of 2-butene because a methyl group is attached to each carbon of the double bond.

43. Visual representations of stereoisomers – substituted cyclohexanes
Equatorial = parallel to the mean plane
Axial = perpendicular to the mean plane.
Cis = both equatorial
Trans = 1 axial, 1 equatorial

44. Optical Isomers
A carbon with four different atoms or groups attached is an asymmetric carbon.
Pairs of molecules that differ only in the way that four different groups are arranged around a central carbon atom are called optical isomers.
H, F, Cl, and Br are attached to a single carbon atom
Mirror images are non superimposable

45. Which compound has an asymmetric carbon?
1.)
Not asymmetric, central carbon has two CH3 groups attached.
2.)
Central carbon is asymmetric, one H, one OH, one CH3, and one CH2CH3 group attached
3.)
Central carbon is asymmetric, one Cl, one H, one CH3, and one CHO
4.)
Not asymmetric, central carbon has two CH3 groups attached.

46. Were you paying attention?
Structural isomers have different properties because they have
a different number of bonds.
different types of bonds.
different substituents.
a different order of atoms.

47. 2. Substituent groups on opposite sides of a double bond are said to be in the _______ configuration. If the groups are on the same side of the bond, then they are in the _______ configuration.
cis, trans
trans, cis
trans, iso
stereo, cis

48. 3. A carbon atom that has four different substituents always forms
an optical isomer.
a saturated hydrocarbon.
a geometric isomer.
an unsaturated hydrocarbon.

49. Hydrocarbon Rings
Cyclic hydrocarbons – compounds that contain a hydrocarbon ring
Saturated hydrocarbons
CnH2n : (CH2)n

50. Hydrocarbon Rings

51. Aromatic Hydrocarbons
Aromatic compound – organic compound that contains a benzene ring or other ring in which the bonding is like that of benzene.
Benzene (C6H6)

52. Aromatic Hydrocarbon - Benzene
Bonding electrons between carbon atoms are shared evenly around the ring.
Switching, or resonating, between two arrangements of alternating double and single bonds.

53. Aromatic Hydrocarbon - Benzene
3 symbols used to represent benzene
(aka arene)
Space filled model

54. Substituted Aromatic Compounds
Compounds with a substituent on a benzene ring are named as a derivative of benzene. When benzene is a substituent, it is called a phenyl group

55. Benzene Derivatives
Substituent groups that incorporate a benzene ring:
1. Phenyl Benzyl

56. Benzene Derivatives
Disubstituted benzenes: the following prefixes are used:
Ortho- for 1,2- substituents
Meta- for 1,3- substituents
Para- for 1,4- substituents

57. Some singular, common names for disubstituted benzene derivatives are shown below. Isomers are distinguished by the above prefixes.
Toluidine
Xylene
Cresol

58. Were you paying attention?
When an alkane has a benzene ring as a substituent, the ring is called _______ group.
a benzene
a toluene
a phenyl
an arene

59. Review of Some Terms Alkane – Alkene – Alkyne – Cycloalkane –
Aliphatic –
Aromatic –
Alkyl group –
a hydrocarbon containing only single covalent bonds; saturated hydrocarbons.
a hydrocarbon containing one or more carbon-carbon double bonds; unsaturated hydrocarbons.
a hydrocarbon containing a carbon-carbon triple bond, unsaturated carbon.
an alicyclic hydrocarbon with a saturated ring.
any straight-chain or branched-chain alkane, alkene, or alkyne.
an organic compound that contains a benzene ring or other ring in which the bonding is like that of benzene.
a hydrocarbon substituent. Ex. the methyl group (–CH3)

60. How are organic compounds classified?
functional group is a specific arrangement of atoms in an organic compound that is capable of characteristic chemical reactions

62. Halogen Substituents
Halocarbons – a class of organic compounds containing covalently bonded F, Cl, Br, or I; all halogens (Group 7 nonmetals)
IUPAC: named as substituents on parent hydrocarbon
Common name: Consists of 2 parts
Name the hydrocarbon portion of the molecule as an alkyl group, such as methyl- or ethyl-
Give the halogen an –ide ending.
Fluorine
Fluoro-
Chlorine
Chloro-
Bromine
Bromo-
Iodine
Iodo-

63. Halogen Substituents
Alkyl halides - halocarbons in which a halogen is attached to a carbon of an aliphatic chain
Aryl halides - Halocarbons in which a halogen is attached to a carbon of an aromatic (arene) ring

64. Halogen Substituents
Alkyl halide
Alkyl halide
Aryl halide

66. How are halocarbons prepared?
A common type of organic reaction is a substitution reaction, in which an atom, or a group of atoms, replaces another atom or group of atoms.
A halogen can replace a hydrogen atom on an alkane to produce a halocarbon.

67. Substitution Rx.
A halogen can replace a hydrogen atom on an alkane to produce a halocarbon.
A catalyst is needed to break relatively strong covalent bonds.

68. Substitution Rx.
Simple halogenation reactions can produce a mixture of mono-, di-, tri-, and tetrachloromethanes.
Common names are in parenthesis

69. Treating benzene with a halogen in the presence of a catalyst causes the substitution of a hydrogen atom in the ring.

70. Were you paying attention?
Organic molecules are classified according to their
functional groups.
longest chain.
derivatives.
number of rings.

71. 2. What is the correct IUPAC name for the compound CH2BrCH2CH2Br?
methylbromoethylbromide
dibromopropane
1,3-dibromopropane
propyl-1,3-dibromide

72. 3. Which reaction will produce a halocarbon?
hydrogenation of an alkyl halide
substitution reaction of a halogen with an alkane
reaction of potassium hydroxide with an aryl halide
reaction of sodium hydroxide with an alkyl halide

73. How are functional groups introduced to alkenes?
Addition reactions of alkenes are an important method of introducing new functional groups into organic molecules.
In an addition reaction, a substance is added at the double or triple bond of an alkene or alkyne.
Double and triple bonds between carbon atoms are much more reactive than single bonds between carbon atoms.

74. Addition Rx. Addition rx. across a double bond.
Hydrogen halides, such as HBr or HCl add to a double bond to produce a monosubstituted halocarbon.

75. Addition Rx.
When the reagent X-Y is a halogen molecule such as chlorine or bromine, the product of the rx is a disubstituted halocarbon.
Bromine can be used to identify unsaturated compounds. a) Bromine has a brownish-orange color. b) A few drops of bromine solution are added to an unsaturated organic compound. c) The bromine reacts to form a colorless halocarbon.

76. Addition Rx. (Reduction)
The addition of hydrogen to a carbon–carbon double bond to produce an alkane is called a hydrogenation reaction.
Hydrogenation reactions usually require a catalyst. Platinum (Pt) or Palladium (Pd), high heat & pressure.

77. Addition Rx. (Reduction)

78. Were you paying attention?
What type of reaction would convert CH2=CH—CH3 into CHBr—CHBr—CH3?
substitution
hydrogenation
addition
hydration