levo

Alkanes

Alkanes as saturated hydrocarbons

  • 3 things to know
  • Unit AS 2

Overview

Term hydrocarbon, general formula of the alkanes and bond joins the carbon atoms in an alkane.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

What is meant by the term hydrocarbon?

Key term

Why are alkanes described as saturated hydrocarbons?

Key term

State the general formula of the alkanes.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is meant by the term hydrocarbon?

    Model answer

    A hydrocarbon is a compound containing the elements carbon and hydrogen only.

  2. 2

    Why are alkanes described as saturated hydrocarbons?

    Model answer

    Every bond between the carbon atoms is a single bond, so each molecule already holds the largest possible number of hydrogen atoms and cannot take up any more.

  3. 3

    State the general formula of the alkanes.

    Model answer

    The alkanes have the general formula CₙH₂ₙ₊₂.

  4. 4

    Give the molecular formula of the unbranched alkane containing eight carbon atoms.

    Model answer

    Putting n = 8 into CₙH₂ₙ₊₂ gives the molecular formula C₈H₁₈.

  5. 5

    What type of bond joins the carbon atoms in an alkane?

    Model answer

    The carbon atoms are joined by single covalent sigma bonds formed by the head-on overlap of orbitals.

  6. 6

    State the bond angle around each carbon atom in an alkane and explain it.

    Model answer

    The bond angle is 109.5°, because each carbon atom has four bonding pairs of electrons that repel one another equally into a tetrahedral arrangement.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Formulae, Equations and Amounts of Substance
Atomic Structure
Bonding
Intermolecular Forces and Structure

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

Yellow to .
brownbluegreen

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AThe reactants total 159.6 + 84.0 = 243.6.
BThe two moles of iron have a mass of 111.6.
CThe atom economy is 45.8%.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

There are 1000 cm³ in one dm³.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Alkanes, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Or £46 a year, about £3.83 a month. Cancel anytime.