Formulae and Facts

Question 1

Empirical Formula

Answer 1

The simplest whole number ratio of atoms of each element in a compound. e.g. C1H2.

Question 2

Molecular Formula

Answer 2

The true number of atoms of each element in a compound. e.g. C2C4 (ethene).

Question 3

General Formula

Answer 3

All members of a homologous organic series follow the general formula. e.g. Alkanes = CnH2n+2.

Question 4

Structural Formula

Answer 4

Shows the structural arrangement of atoms within a molecule. e.g. What links to each carbon atom but not the bonds between the carbons and the hydrogens.

Question 5

Displayed Formula

Answer 5

Shows every atom and every bond in an organic bond. e.g. Opposed to the structural formula, it does show the bonds between the carbons and the hydrogens.

Question 6

Homologous Series

Answer 6

A family of hydrocarbons (e.g. alkanes) with similar chemical and graded physical properties who share the same general formula.

Question 7

Isomers

Answer 7

Molecules with the same amount and types of molecules but structured differently* so called differently. e.g. Butane and 2-methylpropane.

Same molecular formula, different structural formula

Question 8

Functional Group

Answer 8

A certain group of atoms that can appear in many different compounds and affects them all in the same way. (similar chemical properties)

Question 9

Hydrocarbons

Answer 9

Molecules containing only hydrogen and carbon atoms. Alkanes and Alkenes are hydrocarbons.

Question 10

Other Organic Compounds

Answer 10

Molecules can contain oxygen, sulphur, chlorine atoms etc. These are not hydrocarbons.

Question 11

Carbon Monoxide

Answer 11

A colourless, odourless, poisonous gas.
It combines with haemoglobin in the blood, rendering it unable to carry oxygen around the body.
In large amounts, can restrict oxygen levels in the body enought for illness and even death.
Affects smaller children more than adults.