{Chemistry 20 ReviewElectrons, Protons, NeutronsAtomic/Molar MassLewis Diagrams & Structural FormulasNumber of Bonding ElectronsIntermolecular ForcesHydrocarbons and Melting/Boiling Point

Chemistry 20 ReviewElectrons, Protons, Neutrons…

Number of Protons is ALWAYS equal to the Atomic Number…..the number found on the periodic table.

Number of Electrons is equal to Protons ONLY IN NEUTRAL ATOMS!

In (Non-Un-Dis?)…..compounds/ions that are not neutral you have to look at the Overall Charge to determine how many electrons.

Overall Charge is the Protons (+) + Electrons (-).

Neutrons are usually equal to the number of protons…..***You need to know the Atomic/Molar mass to know for sure.***

Chemistry 20 ReviewAtomic/Molar Mass

Atomic mass is the combined weight of Protons, Neutrons, and Electrons.

Protons and Neutrons have the most weight….that extra little bit….usually a few decimals is the weight of the electrons…..they have a very small weight.

Atomic Mass….. H 1.01g/mol C 12.01g/mol Cl35.45g/mol

Atomic mass is equal to [#P + #N]….the extra little bit is the weight of the electrons.

Chemistry 20 ReviewAtomic/Molar Mass

How do you calculate the atomic/molar mass of a compound?

H2O?2 X H = 2.02g/mol1 X O = 16.00g/molTotal = 18.02g/mol

C6H12O6?6 X C = 72.00g/mol12 X H = 12.12g/mol6 X O = 96.00g/molTotal = 180.12g/mol

Chemistry 20 ReviewLewis Diagrams

Also known as Lewis Dot Diagrams.Diagrams where you put the symbol of the element in the center and draw the Valence electrons around it represented by dots.

Oxygen is in group VI A (group 16)…….so it has 6 valence electrons.So start at the top and go clock wise until you have put 6 “dots” around the O.

DONE

Chemistry 20 ReviewBonding Electrons

When we draw the Lewis Dot Diagram for oxygen we notice that there are 2 pairs.And 2 single electrons.

Single electrons are electrons that can form bonds.Singles electrons are called bonding electrons.

So, how many bonds can oxygen form?

2

Chemistry 20 ReviewStructural Diagrams/Formulae

Structural diagrams look very similar to Lewis diagrams.But they do not show electrons, they only show bonds in a compound OR polyatomic atom…H2 Cl2, F2, I2 S8 P4

CH4 CH

If we draw a Carbon Lewis Dot Diagram OR look to see its in group 14 which means it has 4 bonding electrons.

Well carbon can form 4 bonds and there’s 4 hydrogen’s, so put one on each side and connect them with a line to show a bond.

HH

H

Chemistry 20 ReviewIntermolecular Forces

3 Types of Intermolecular forces:

1. Dipole-Dipole Forces• Using electronegativity to assign

dipoles• Polar and Non-Polar Molecules

2. London Dispersion• Momentary Dipole-Dipole attraction.• Random chance of electrons of a

bond being unequally shared.3. Hydrogen Bonding

• Hydrogen bonded to another atom other than hydrogen.

• H-O H-Cl H-F H-N

Chemistry 20 ReviewHydrocarbon Melting/Boiling Points

A general rule to follow is that the greater the number of C’s and H’s a compounds has the higher its melting and boiling points.

Chemistry 20 ReviewPractice

Hydrocarbons are compounds containing Hydrogen and Carbon (Often referred to as fossil fuels).CH4

C2H6

C3H8

Hydrocarbons

What Kind of Chemical Potential Energy Do We Use…Have A Lot of In Alberta?

Where did the energy in things like Oil and Gas come from….originally?

From The Sun To Your Gas Tank

Photosynthesis Dead PlantCovered By Sediment

Millions of Years Pass By Fossil Fuel

Fossil fuels are the main source of hydrocarbons.There are many forms of fossil fuels such as:

Organic & InorganicOrganic

CompoundsInorganic

CompoundsComes from living sources, things that are now or were once alive.Often called Natural compounds because they can be found in nature.

Source of fossil fuels.

Main source of hydrocarbons.

“CHON”

Carbon, Hydrogen, Oxygen, Nitrogen.

Synthesized compounds.

Not natural, can be found, but not a large part of living things.

Usually Ionic Compounds.

CO3 CN- Na2CO3 NaCl CaC2

….Not CHON…..

Opposite or organic….. Its spelt different……It has “In” in front...

Refining Fossil FuelsMost fossil fuels in their raw/natural form cannot be used by humans.

In order to make fossil fuels into a form that can be used by humans they need to be refined.

Raw natural gas is actually a mixture of different hydrocarbons and poisonous Hydrogen Sulfide (H2S(g)) and needs to be refined before it can be used.

The first process that has to happen to raw natural gas is the removal of the poisonous component through a process called “sweetening”.

The removed Poisonous Hydrogen Sulfide (H2S(g)) and SO2(g) are then further reacted in a “Clause Converter” and are tuned into solid sulfur.

But even after the removal of the Hydrogen Sulfide (H2S(g)) the raw natural gas still contains a number of other hydrocarbons and must be further refined before it can be used.

Raw Natural Gas

***In general any hydrocarbon longer than 4 carbons is liquid at room temperature.

Naming Hydrocarbon “Chains”

1. you have to count the number of carbons in the hydrocarbon chain and use the prefix .Number of Carbons

IUPAC Name

1 Meth

2 Eth

3 Prop

4 But

5 Pent

Naming Hydrocarbon “Chains”

2. you have to determine is the hydrocarbon is saturated or unsaturated.

Saturated Hydrocarbons:

Unsaturated Hydrocarbons:

Saturated Hydrocarbons are hydrogen and carbon containing compounds that contain ONLY single bonds between carbons. Maximum number of hydrogens.

Unsaturated hydrocarbons are compounds that contain double or triple bonds between carbons.

Naming Hydrocarbon “Chains”

Alkanes, Alkenes, and AlkynesSaturated

SINGLE BONDS

Unsaturated DOUBLE BONDS Unsaturated

TRIPLE BONDS

Practice:

1 2 3 4

1. Count the number of carbons in the chain.

ButHydrocarbon Name:

2. Saturated (ONLY SINGLE BONDS) or Unsaturated (DOUBLE –ene or Triple-Yne)

ane

Structural Formula

Practice:1. Count the number

of carbons in the chain.

PentHydrocarbon Name:

2. Saturated (ONLY SINGLE BONDS) or Unsaturated (DOUBLE –ene or Triple-Yne)

ane

Structural Formula

Practice:

DecaneHydrocarbon Name:

Structural Formula

Branched Alkanes

Not all hydrocarbons are straight chains, often they have side branches like a tree.

Branched alkanes get named the same way as far as the long Parent chain is concerned.

You still look for the longest number of carbons in a row.

Branched Alkanes

1. Count the number of carbons in the chain.

But

2. Saturated (ONLY SINGLE BONDS) or Unsaturated (DOUBLE –ene or Triple-Yne)

ane

***To name the side branch, you need to indicate which carbon it is connected to.***

Branched Alkanes

Butane

So we have to number the longest chain so we can say where the “branch” is connected.

1 2 3 4

OrSo…

1234

***The rule is you number the carbons so that the branch is on the lowest number***

Branched Alkanes

Butane

1 2 3 4

So lets look just at the branch.

So just like with the parent chain, how many carbons long is the branch?

1 Carbon

Prefix for 1 carbon?Meth

Meth

***All side branches end in –yl***

yl

Branched Alkanes

Butane

1 2 3 4

Methyl

Last thing.

What number carbon is the Methyl branch connected to?

2-

Practice(easy)

1.

2.

Pentane

3. Number the carbons so the chain is on lowest carbon number.

1 2 3 4 5

4. Name the branch.

Ethyl5. What carbon is the

branch on?3-

Practice(Advanced)

1.

2.

Pentane

3. Number the carbons so the chain is on lowest carbon number.

1 2 3 4 5

4. Name the branches.Alphabetically…

Ethyl5. What carbon is the

branch on?3-

Ethyl

Methyl Methyl

Di

Dimethyl-2,4-

P. 371

Cycloalkanes are hydrocarbons that are bound together in a ring.

Name them the same as a straight branch, just write “Cyclo” in front.

1. 2.

hexaneCyclo

1. 2.

pentanecyclo

3. Number the carbons so the chain is on lowest carbon number…..Clockwise-Counter clockwise, whatever.

12

3

45

4. Name the branch.Methyl

MethylDi

dimethyl

5.

What carbon is the branch on?

1,2-

Different Hydrocarbon Formulae

Different Hydrocarbon Formulae

1. 2.

pentCyclo

3. Number the carbons so the chain is on lowest carbon number.

**** Have to start numbering at double bond…it has priority***

1

2

3

45Name the branch.4.

Challenging

Methyl

Methyl

Di

dimethyl

5.

What carbon is the branch on?

2,3-

pentCyclo

1

2

3

45

Challenging

Methyl

Methyl

Di

dimethyl2,3-

Are we done?

What carbon is the double bond on?

If we always number starting at the double bond…do we need to say 1?

ene

Saturated:

Unsaturated:

Contains as many Hydrogens as possible.

Do not contain as many Hydrogens as possible.

Hydrogenation:

The process of adding H2(g) to an UNSATURATED hydrocarbon causing it to become more saturated.

The naming system for Alkenes and Alkynes is the same as for Alkenes.

1. Count the number of carbons in the chain.

2. Saturated (ONLY SINGLE BONDS) or Unsaturated (DOUBLE –ene or Triple-Yne)

3. Number the carbons so the chain is on lowest carbon number.Name the branch.4.

5.

What carbon is the branch on?

1 2 3 4

Butenemethyl2-

4,4 – dimethyl pentene

4,4 – dimethyl hept-2-yne

5-ethyl-4-methylhept-2-yne

***you have to number the chain so that the “yne” as the lowest number***

Hydrocarbon cracking is the process of breaking large(single bonded….saturated) hydrocarbons into smaller (often unsaturated) hydrocarbons.

Hydrocarbon cracking is done HIGH TEMPERATURESWITH OR WITHOUT a catalyst.

HC-C-C-C-C-C-C-CHH

HHHHH HH

HHHHH HHH+ Heat

HC-C-C-C-HH

HHHH

HHHHC-C-C-C-H

HHHH

HHHH

Ethane cracking is the a special hydrocarbon cracking in which Ethane (single bonded-Saturated) is “cracked” into Ethyne (double bonded-unsaturated).

Aliphatics:

Aromatics:

Straight chain alkanes that DO NOT contain a benzene ring.

Hydrocarbon compounds that contain a benzene ring.

If a hydrocarbon contains this structure, its aromatic.

Don’t worry about naming compounds with benzene…..yet…..

Hydrocarbons

End of Chemist

ry 20