gcse core chemistry exam tip; the line between 2 atoms in the molecule is the chemical bond holding...
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GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
KeywordsKeywords:: Distillation, hydrocarbons, alkanes, molecular formula, Distillation, hydrocarbons, alkanes, molecular formula, saturated hydrocarbons, structural formulasaturated hydrocarbons, structural formula
Prior Learning:Prior Learning:Metal extraction, properties of metals links to usageMetal extraction, properties of metals links to usage
GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
Learning Objectives: Identify and explain •What crude oil is.• What an alkane is and how to represent them
I will be successful in this lesson if I can: (Level C)• Recognise that crude oil is a mixture and state that it can be separated by distillation.• Define and recognise simple alkanes.• Write the correct chemical formula of an alkane represented by a structural formula.(Level A)• Given named examples, draw diagrams and write the formulae of simple alkanes.• Recall and use the formula CnH2n+2 to give the formula of an alkane, when n is given.
GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
MATCHING – Which matches?
Alkane
Hydrocarbon
Alkane A molecule that contains only hydrogen and carbon atoms
A saturated hydrocarbon
More than 1 substance, not chemically joined together
GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
You have 2 mins to list as much information as you can about this
diagram
GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
Types of FormulasTypes of Formulas
1. Molecular formula tells us the number of each type of atom
2. Structural formula tells us how the atoms are bonded.
Which type of formula was shown on the Which type of formula was shown on the previous slide?previous slide?
What is the molecular formula?What is the molecular formula?
STRUCTURAL FORMULA
C4H10
GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
Alkanes:
are considered to be saturated!
How many electrons does H have in the outer shell?
How many does C have?
What can this tell us about the bonding capabilities of alkanes?
METH- = 1, ETH- = 2, PROP- = 3, BUT- = 4METH- = 1, ETH- = 2, PROP- = 3, BUT- = 4
Use 1.1. The molymod kits,The molymod kits,2.2. Your knowledge of electrons in the Your knowledge of electrons in the outer shell of H & Couter shell of H & C3. The above prefixes3. The above prefixes To build & name the first four alkanes
CHALLENGE
Write a mathematical formula to work out the little numbers on C & H
GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
Patterns?
Can you see any patterns in Can you see any patterns in these first four alkanes?these first four alkanes?
If boys were Hydrogen atoms and girls were carbon atoms act out
1. Methane
2. Ethane
3. Propane
4. Butane
Devise the general formula for alkanes based on patterns identified in these first 4
Using your formula, if a hydrocarbon had 45 carbon atoms
How many hydrogen atoms will it have?What is its molecular formula?
CnH2n+2,So C45H (2x45) + 2
which isC45H92
GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
DEMO: Let’s investigate alkanes
Starting with the smallest carbon chain Starting with the smallest carbon chain complete the following for all alkanes;complete the following for all alkanes;
1. Pour into a metal bowl containing mineral wool.
2. Comment on viscosity and colour
3. Ignite.
4. Comment on the ease of lighting & colour of the flame & time of burn.
GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
HOMEWORK (typical exam style questions): How do the properties of alkanes depend on the length of the carbon chain?
GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
We say that alkanes are a chemical family, but just like your family no 2
alkanes are the same.
Parrafin
OctanePentane
GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
Alkane seriesAlkane seriesNAME Formula B.P./oC M.P./oC State @ room temp. (20oC)
Methane CH4 -162 -183 gas
Ethane C2H6 -89 -172 gas
Propane C3H8 -42 -188 gas
Butane C4H10 -0.5 -135 gas
Pentane C5H12 36 -130 liquid
Hexane C6H14 69 -95 liquid
Heptane C7H16 98 -91 liquid
Octane C8H18 126 -57 liquid
Nonane C9H20 151 -54 liquid
Decane C10H22 174 -30 Liquid (the next 6 are liquid and the rest are solid)
As the number of carbon atoms increases, what happens to the boiling & melting points?
GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
How would you separate a hydrocarbon?Crude oil contains many different
compounds that boil at different temperatures so in order for them to be useful we have to separate crude oil into its fractions.
Simple distillation can separate liquids that boil at different temperature ranges.
Most compounds in crude oil are hydrocarbons (mainly alkanes).
GCSE Core Chemistry
Exam tip; The line between 2 atoms in the molecule is the Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together chemical bond holding them together
Learning Objectives: Identify and explain •What crude oil is.• What an alkane is and how to represent them
I will be successful in this lesson if I can: (Level C)• Recognise that crude oil is a mixture and state that it can be separated by distillation.• Define and recognise simple alkanes.• Write the correct chemical formula of an alkane represented by a structural formula.(Level A)• Given named examples, draw diagrams and write the formulae of simple alkanes.• Recall and use the formula CnH2n+2 to give the formula of an alkane, when n is given.