Unit 1 - Foundation Chemistry (Key Terms)

Question 1

Alkane?

Answer 1

A hydrocarbon with C-C and C-H single bonds only, with the general formula Cn H2n+2.

Question 2

Allotropes?

Answer 2

Pure elements which can exist in different physical forms in which their atoms are arranged differently. E.g. Diamond, Graphite & Buckminsterfullerene are allotropes of carbon.

Question 3

Atom Economy?

Answer 3

The efficiency of a chemical reaction by comparing total number of atoms in the product with total number of atoms in starting materials.
Defined by:
Mass of Desired Product / Total Mass of Reactants x 100

Question 4

Avogadro Constant?

Answer 4

The total number of particles in a mole of a substance.

Question 5

Catalyst?

Answer 5

A substance that alters the rate of a chemical reaction but is not used up in the reaction.

Question 6

Catalytic Cracking / Cracking?

Answer 6

With the help of a catalyst or high temperature, the breaking of long-chain alkane molecules into shorter chain hydrocarbons (alkanes & alkenes).

Question 7

Carbon-neutral?

Answer 7

A process, in which as much carbon dioxide is absorbed from the air as is released.

Question 8

Coordinate / Dative Covalent Bonding?

Answer 8

Covalent bonding in which both electrons in the bond come from one of the atoms in the bond.

Question 9

Covalent Bonding?

Answer 9

A pair of electrons shared between 2 atoms.

Question 10

Delocalised?

Answer 10

Electrons that are spread over several atoms & help to bond them together.

Question 11

Dipole-Dipole Force?

Answer 11

An intermolecular force that results from the attraction between molecules with permanent dipoles.

Question 12

Displacement Reactions?

Answer 12

A chemical reaction in which one or a group of atoms replaces another in a compound.
E.g. Zn + CuO –> ZnO + Cu

Question 13

Displayed Formula?

Answer 13

The formula of a compound drawn out so that each atom & bond is shown.

Question 14

Electron Pair Repulsion Theory?

Answer 14

A theory which explains the shapes of simple molecules by assuming that pairs of electrons around a central atom repel each other (as far away as possible).

Question 15

Electronegativity?

Answer 15

The power of an atom to attract the electrons in a covalent bond.

Question 16

Empirical Formula?

Answer 16

The simplest whole number ratio in which atoms in a compound combine together.

Question 17

Endothermic?

Answer 17

A reaction in which heat is taken in as reactants change to products, the temperature drops.

Question 18

Enthalpy Change?

Answer 18

A measure of heat energy given out or taken in when a chemical or physical change occurs at constant pressure.

Question 19

Exothermic?

Answer 19

A reaction in which heat is given out as reactants change to products, the temperature rises.

Question 20

Fraction?

Answer 20

A mixture of hydrocarbons with similar boiling points.

Question 21

Free Radical?

Answer 21

A chemical species with an unpaired electron - highly reactive.

Question 22

Functional Group?

Answer 22

The part of a molecule of a (carbon) compound which is responsible for the characteristic reactions of that molecule.
E.g. Alkenes have a C=C double bond.

Question 23

Group?

Answer 23

A vertical column of elements in the periodic table. The elements have similar properties as they have the same outer electron arrangement.

Question 24

Homologous Series

Answer 24

A set of organic compounds with the same function groups. Compounds differ in their hydrocarbon chain lengths.

Question 25

Hydrogen Bonding?

Answer 25

An intermolecular force in which a hydrogen atom covalently bonded to an electronegative atom interacts with another elctronegative atom.

Question 26

Incomplete Combustion?

Answer 26

A combustion reaction in which there is insufficient oxygen for all the carbon in the fuel to burn to carbon dioxide. Carbon monoxide &/or carbon (soot) are formed.

Question 27

Ionic Bonding?

Answer 27

A chemical bond in which an electron or electrons are transferred from one atom to another. A strong electrostatic force of attraction between oppositely charged ions is formed.

Question 28

Ionisation Energy?

Answer 28

The energy required to remove a mole of electrons from a mole of gaseous atoms or ions.

Question 29

Isomers?

Answer 29

One of two (or more) compounds with same molecular formula but different structural formula. E.g. Same atoms arranged differently.

Question 30

Isotopes?

Answer 30

Atoms of the same element (same atomic number) but different mass numbers (different numbers of neutrons).

Question 31

Atomic Number?

Answer 31

The number of protons in the nucleus of an atom.

Question 32

Mass Number?

Answer 32

The total number of protons & neutrons in the nucleus of an atom.

Question 33

Fractional Distillation?

Answer 33

The physical separation of a mixture of liquids which have different boiling points.

Question 34

Chain Isomers?

Answer 34

Compounds with the same molecular formula, but the carbon "backbone" of the molecule is of different lengths of side branches. E.g. Butane & Methylpropane.

Question 35

Function Group Isomers?

Answer 35

Compounds with the same molecular force, but molecules have a different functional group. E.g. C4H8 could be butene (alkene) or cyclobutane (cyclic alkane).

Question 36

Lone Pair / Unshared Pair?

Answer 36

A pair of electrons in the outer shell of an atom that's not involved in bonding.

Question 37

Metallic Bonding?

Answer 37

A chemical bond in which outer electrons are spread over a lattice of metal ions.

Question 38

Mole?

Answer 38

A quantity of a substance that contains the Avogadro number of particles.

Question 39

Molarity (M)?

Answer 39

The concentration of a solution expressed in moles per cubic decimetre (litre).

Question 40

Molecular Formula?

Answer 40

The number of atoms of each element in a molecule of a compound.

Question 41

Monomer?

Answer 41

A small molecule that combines with many other monomers to form a polymer.

Question 42

Nucleus?

Answer 42

The tiny, positively charged centre of an atom, made up of protons & neutrons.

Question 43

Percentage Yield?

Answer 43

The actual amount of product produced divided by the theoretical amount expressed as a percentage.

Question 44

Period?

Answer 44

A horizontal row of elements in the periodic table. There are trends in the properties of elements across a period.

Question 45

Periodicity?

Answer 45

The regular recurrence of the properties of elements when arranged in atomic number order (periodic table).

Question 46

Polar Molecule (permanent dipole)?

Answer 46

A molecule in which the charge is not symmetrically distributed; one area is positively charged & another negatively charged.

Question 47

Positional Isomers?

Answer 47

Compounds with same molecular formula & same carbon chain length, but substituent or functional group is in different place along the chain. E.g. 1-chloropropane & 2-chloropropane.

Question 48

Reduction?

Answer 48

Atom(s) gain electrons.

Question 49

Oxidation?

Answer 49

Atom(s) lose electrons.

Question 50

Relative Atomic Mass?

Answer 50

The average mass of an atom of an element compared with 1/12th the mass of a carbon-12 atom.

Question 51

Relative Molecular Mass?

Answer 51

The average mass of a molecule compared with 1/12th the mass of a carbon-12 atom.

Question 52

Structural Formula?

Answer 52

Each carbon atom is written separately with atom(s) attached to it. E.g. Butan-2-ol is written CH3CH2CH(OH)CH3

Question 53

Structural Isomer?

Answer 53

Compounds with the same molecular formula, but different structural formulae. Three types of structural isomerism: Chain, Positional & Functional Group.

Question 54

Van der Waals force?

Answer 54

An intermolecular force of attraction caused by instantaneous dipoles & acts between all atoms & molecules.