GCSE Core Chemistry Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together Keywords: Distillation, hydrocarbons, alkanes, molecular formula, saturated hydrocarbons, structural formula Prior Learning: Metal extraction, properties of metals links to usage

GCSE Core Chemistry Exam tip; The line between 2 atoms in the molecule is the 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 C n H 2n+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 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 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 chemical bond holding them together Types 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 previous slide? What is the molecular formula? STRUCTURAL FORMULA C 4 H 10

GCSE Core Chemistry Exam tip; The line between 2 atoms in the molecule is the 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- = 4 Use 1.The molymod kits, 2.Your knowledge of electrons in the outer shell of H & C 3. 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 chemical bond holding them together Patterns? Can you see any patterns in 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? C n H 2n+2, So C 45 H (2x45) + 2 which is C 45 H 92

GCSE Core Chemistry Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together DEMO: Let’s investigate alkanes Starting with the smallest carbon chain 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 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 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 Octane Pentane

GCSE Core Chemistry Exam tip; The line between 2 atoms in the molecule is the chemical bond holding them together Alkane series NAMEFormulaB.P./ o CM.P./ o room temp. (20 o C) MethaneCH gas EthaneC2H6C2H gas PropaneC3H8C3H gas ButaneC 4 H gas PentaneC 5 H liquid HexaneC 6 H liquid HeptaneC 7 H liquid OctaneC 8 H liquid NonaneC 9 H liquid DecaneC 10 H 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 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 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 C n H 2n+2 to give the formula of an alkane, when n is given.