Definitions

Question 1

What are isotopes?

Answer 1

Atoms of the same element with the same number of protons but different number of neutrons.

Question 2

What is relative isotopic mass?

Answer 2

The mass of an isotope compared with 1/12 of the mass of an atom of carbon-12.

Question 3

What is relative atomic mass?

Answer 3

The weighted mean mass of an atom of an element compared with 1/12 of the mass of an atom of carbon-12.

Question 4

What is Avogadro constant?

Answer 4

6.02 x 10^23, the number of atoms per mole of carbon-12.

Question 5

What is empirical formula?

Answer 5

The simplest whole number ratio of atoms of each element present in a compound.

Question 6

What is molecular formula?

Answer 6

The number and type of atoms of each element in a molecule.

Question 7

What is limiting reagent?

Answer 7

The reactant that is not in excess, which will be used up first and stop the reaction.

Question 8

What is an acid?

Answer 8

A species that releases H+ ions in aqueous solution.

Question 9

What is a base?

Answer 9

A compound that neutralises an acid to form a salt.

Question 10

What is an alkali?

Answer 10

A type of base that dissolves in water and releases OH- (hydroxide) ions in aqueous solution.

Question 11

What is a strong acid?

Answer 11

An acid that completely dissociates in solution and release all H+ ions.

Question 12

What is a weak acid?

Answer 12

An acid that partially dissociates in solution and releases some H+ ions.

Question 13

What is neutralisation?

Answer 13

The reaction of:
1. H+ and OH– to form H2O
2. acid and base to form salt

Question 14

What is titration?

Answer 14

A technique used to measure the volume of one solution that reacts exactly with another solution.

Question 15

What is a standard solution?

Answer 15

A solution of known concentration

Question 16

What is oxidation number?

Answer 16

The number of electrons involved in bonding to a different element.

Question 17

What is oxidation?

Answer 17

Loss of electrons and an increase in oxidation number.

Question 18

What is reduction?

Answer 18

Gain of electrons and a decrease in oxidation number.

Question 19

What is a redox reaction?

Answer 19

A reaction that involves both oxidation and reduction.

Question 20

What is disproportionation?

Answer 20

When the same element is both oxidised and reduced during a reaction.

Question 21

What are shells?

Answer 21

A group of atomic orbitals with the same principal quantum number N.

Question 22

What are atomic orbitals?

Answer 22

A region around the nucleus that can hold up to two electrons, with opposite spins.

Question 23

What is ionic bonding?

Answer 23

Electrostatic attraction between positive and negative ions.

Question 24

What are giant ionic lattices?

Answer 24

A three-dimensional structure of oppositely charged ions that are strongly attracted in all directions, bonded together by strong ionic bonds.

Question 25

What is covalent bonding?

Answer 25

Strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.

Question 26

What is dative covalent bonding?

Answer 26

A shared pair of electrons in which the bonded pair has been provided by one of the bonding atom only.

Question 27

What is electronegativity?

Answer 27

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

Question 28

What is a polar molecule?

Answer 28

A molecule with an overall dipole, considering any dipoles across bonds and the shape of the molecule.

Question 29

What is a non-polar molecule?

Answer 29

A molecule with no charge separation across its bonds.

Question 30

What is dipole?

Answer 30

Separation of opposite charges across a bond with one atom having a δ+ charge and one atom having a δ- charge.

Question 31

What is permanent dipole?

Answer 31

A dipole in a polar covalent bond that doesn't change.

Question 32

What are intermolecular forces?

Answer 32

A weak attractive force between molecules

Question 33

What is a simple molecular lattice?

Answer 33

A three-dimensional structure of molecules, bonded together by weak intermolecular forces.

Question 34

What is hydrogen bond?

Answer 34

A strong dipole-dipole attraction between a hydrogen atom and a lone pair of electrons on a highly electronegative atom containing N, O or F on a different molecule.

Question 35

What is a general formula?

Answer 35

The simplest algebraic formula of a member of a homologous series.

Question 36

What is a structural formula?

Answer 36

The minimal detail that shows the arrangement of atoms in a molecule.

Question 37

What is a displayed formula?

Answer 37

The relative positioning of atoms and the bonds between them.

Question 38

What is a skeletal formula?

Answer 38

The simplified organic formula, shown by removing hydrogen atoms from alkyl chains, leaving just a carbon skeleton and associated functional groups.

Question 39

What is a hydrocarbon?

Answer 39

A molecule that is made of hydrogen and carbon only.

Question 40

What is a homologous series?

Answer 40

A series of organic compounds that have the same functional group but with each successive (連續的) member differing by CH2.

Question 41

What is a functional group?

Answer 41

An atom that is responsible for the characteristic reactions of a compound.

Question 42

What is aliphatic?

Answer 42

A chain of carbon atoms

Question 43

What is alicyclic?

Answer 43

A ring of carbon atoms

Question 44

What is aromatic?

Answer 44

Anything that contains benzene

Question 45

What is saturated?

Answer 45

Only contains single carbon-carbon bonds

Question 46

What is unsaturated?

Answer 46

Contains at least one multiple carbon-carbon bond

Question 47

What is a structural isomer?

Answer 47

Compounds with the same molecular formula but different structural formula.

Question 48

What is homolytic fission?

Answer 48

The evenly breaking of a covalent bond which each bonding atom receiving one electron from the bonded pair, forming two radicals.

Question 49

What is heterolytic fission?

Answer 49

The breaking of a covalent bond which one bonding atom receiving both electrons from the bonded pair, forming a positive ion and a negative ion.

Question 50

What is a substitution reaction?

Answer 50

An atom/group of atoms on the molecule is swapped with a different atom.

Question 51

What is an addition reaction?

Answer 51

Adding an atom into the original molecule.

Question 52

What is an elimination reaction?

Answer 52

Removing an atom from the original molecule.

Question 53

What is an electrophile?

Answer 53

An electron pair acceptor / a species that is often positively charged and seeks out negatively charged area.

Question 54

What is a nucleophile?

Answer 54

An electron pair donor / a species that is often negatively charged and seeks out positively charged area.

Question 55

What are free radicals?

Answer 55

A species with an unpaired electron

Question 56

What are stereoisomers/geometric isomers?

Answer 56

Isomers that have the same structural formula but different arrangement in space.

Question 57

What is a carbocation?

Answer 57

An ion that contains a positively charged carbon atom.

Question 58

What is addition polymerisation?

Answer 58

Formation of a very long molecular chain by repeated addition reactions of many unsaturated alkene molecules.

Question 59

What are organohalogen molecules?

Answer 59

Compounds that contain at least one halogen joined to a carbon.

Question 60

What is CFC?

Answer 60

Chlorofluorocarbons

Question 61

What is a target molecule?

Answer 61

The compound that the chemist is attempting to prepare by organic synthesis.