Introduction to Chemistry

Question 1

Three types of hydrocarbons (they all begin with ‘a’)

Answer 1

Aliphatic - carbon atoms form straight or branched chains

Alicyclic - carbon atoms form a ring

Aromatic - carbon atoms form a ring but there are also delocalised electrons between the carbon atoms

Question 2

Homologous series

Answer 2

Compounds with:

• the same general formula
• similar chemical properties
• a trend in physical properties
• compounds differ from each other by a CH2 unit

Question 3

Functional group

Answer 3

• a group of atoms which determine the chemical properties of a compound
• this part of the compound will determine the homologous series that it is part of, also when this group of atoms is present in different compounds it will cause them to have similar chemical reactions*

Question 4

9 KEY FUNCTIONAL GROUPS (HANA KEACA)

Answer 4

Halogens (bromo, chloro, iodo)
Alcohol
Nitrile (C triple bond N)
Alkane
Ketone (C with two Rs attached and the an oxygen attached by a double bond)
Ester (C with double bond oxygen and single bond oxygen)
Amine (N with two Hs and one R group attached)
Carboxylic acid (C with a double bond oxygen and a single bond OH)
Alkene

Question 5

Just a lil quick fact for ya …. what is catenation?

Answer 5

The unusual property of carbon atoms where they can form four bonds and so they can connect with other carbon atoms, making a chain.

:)

Question 6

Nomenclature - 5 ideas

Answer 6

1) count longest carbon chain possible
2) use appropriate suffix (eg. aldehydes are ‘al’ - propanAL, esters are ‘yl’ then ‘oate’ - ethYL ethanOATE)
3) the number shows the position of the group (so if it says 3-bromo it means that there is a bromine atom coming off the third carbon)
4) ‘di’ or ‘tri’ is however many groups, eg. Methyl, in the entire compound. (So if there are two methyl groups branching off of the carbon chain then somewhere in the name it will say ‘dimethyl’ ASK WHAT OTHER TYPES OF GROUPS YOU COULD GET)
5) If a chain has different groups so like a bromo, chloro and methyl group, you have to say these in the name according to alphabetical order

Question 7

Structural isomerism

Answer 7

Structural isomerism - compounds have the same molecular formula but a different ?displayed?(ask) and structural formula; the atoms are arranged in a different order.

Chain Isomerism
Isomers will be straight chained or branched

Position isomerism
The basic carbon skeleton remains the same but the functional group branching off changes position. (For example, Butan-1-ol has the OH attached to the last carbon but butan-2-ol has the OH attached to the second carbon) Anotherrrrr example: the functional group changes position on a benzene ring.

Functional group isomerism
Compounds have the same molecular formula but different functional groups [and are essentially completely different] (For example, ethanol and methoxymethane have the molecular formula C2H6O and yet as you can tell from the names they are NOTHING like each other!! Ethanol is an alcohol and methoxymethane is an ether -)

Question 8

Stereoisomerism

Answer 8

Stereoismerism - compounds with the same molecular and structural formula but a different spatial arrangement. ONLY OCCURS IN THINGS WITH DOUBLE BONDS

Geometrical isomerism
This is a type of stereoisomerism, it is also known as cis/trans or E/Z isomerism.

Here we go ….

THREE KEY IDEAS:

• In order for stereoisomerism to occur, the groups attached to the carbon atom cannot be the same, there has to be at least one different group. (Eg. Ethene cannot be a stereoisomerism because the carbon has two hydrogen’s attached to it and these are the same)
• E/Z isomerism exists because there is restricted rotation around a C=C double bond, it cannot rotate 360 degrees, it can only rotate a tiny bit.
• the group with the highest priority is the group with the highest molecular mass.

A            B
    \        /
     C=C
     /       \
   C         D

In the diagram above stereoisomerism CAN occur because both carbons have groups which are different to each other

H          H
  \          /
    C=C
    /      \
  H       H

In the diagram above stereoisomerism CANNOT occur because the carbons both have the same groups attached to them.

E isomers:
Entgagen (opposite), [enemies] an isomer that has the two highest priority groups DIAGONALLY OPPOSITE each other. These are also known as trans isomers when an isomer only has two different groups on the C=C (eg. there are two diagonal Hs and then a diagonal Br and Cl).

Z isomers:
Zusammen (together) [zame zide], an isomer that has the two highest priority groups adjacent to each other. These are also known as cis isomers when an isomer only has two different groups on the C=C.

How to work out the kind of isomer - focus on the double bond then look at the groups attached to it. Work out which two are the highest priority groups by imagining a vertical line through the C=C, adding up the molecular masses and compare which group out of the two on the RHS has a higher mass and which group out of the two on the LHS has a higher mass. Look at the positions of the two highest priority groups to determine if it’s an E or Z isomer.

always make sure that BOTH of the carbons have two different groups attached otherwise it’s not a stereoisomerism at all

Question 9

units of molar mass

Answer 9

g mol^-1