Module 2 - Keywords

Question 1

Isotopes

Answer 1

Atoms of the same element with different numbers of nuetrons and different masses but the same number of protons and electrons

Question 2

Relative isotopic mass

Answer 2

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

Question 3

Relative atomic mass

Answer 3

Weighted mean mass of an atom compared with 1/12 the mass of carbon-12

Question 4

Relative molecular mass, Mr

Answer 4

Mass of a molecule compared with 1/12th the mass of carbon-12

Question 5

Mole

Answer 5

The unit for an amount of substance (6.02x10²³ mol^-1)

Question 6

Avogadro constant

Answer 6

The number of particles per mole, 6.02x10²³ mol^-1

Question 7

Molar mass

Answer 7

Mass per mole, units: gmol^-1

Question 8

Mass spectrometry

Answer 8

Method used to determine the relative abundances of different isotopes

Question 9

Empirical formula

Answer 9

Simplest whole number ratio of atoms of each element present in a compound

Question 10

Molecular formula

Answer 10

Number and type of atoms of each element in a molecule

Question 11

Anhydrous

Answer 11

Contains no water

Question 12

Hydrated

Answer 12

Contains water of crystallisation

Question 13

Ideal gas equation

Answer 13

pV=nRT

Question 14

Stoichiometric relationships

Answer 14

The whole number relationships between particles of reactants and products

Question 15

Percentage yield

Answer 15

actual yield/expected yield x100

Question 16

Atom economy

Answer 16

Useful products/total product x100

Question 17

Acid

Answer 17

Proton donor, release H⁺ in aqueous solution

Question 18

Base

Answer 18

Proton acceptor

Question 19

Alkalis

Answer 19

A substance that releases OH^- ions in aqueous solution

Question 20

Neutralisation reaction

Answer 20

A reaction of H⁺_(aq) + OH^-_(aq) → H₂O_(l)

Question 21

Titration

Answer 21

The slow addition of one solution of a known concentration to a known volume of another solution of unknown concentration until the end point

Question 22

Strong acid

Answer 22

An acid that completely dissociates in water HA → H⁺ + A^-

Question 23

Weak acid

Answer 23

An acid that only partially dissociates in water HA ⇌ H⁺ + A^-

Question 24

Dilute acid

Answer 24

An acid with only a few particles dissolved per litre (e.g. 0.01 moldm^-3)

Question 25

Concentrated acid

Answer 25

An acid with lots of particles dissolved per litre (e.g. 50 moldm^-3)

Question 26

Oxidation number

Answer 26

A measure of the number of electrons involved in bonding. Used to work out what has been oxidised/reduced

Question 27

Oxidation

Answer 27

Loss of electrons, increase in oxidation mumber, adding oxygen

Question 28

Reduction

Answer 28

Gain of electrons, decrease in oxidation number, removing oxygen

Question 29

Redox

Answer 29

A reaction in which one substance is oxidised and another reduced

Question 30

Salt

Answer 30

A compound formed when the hydrogen in an acid is replaced by a metal

Question 31

Orbital

Answer 31

A region around the nucleus that can hold up to 2 electrons, with opposite spins

Question 32

Subshell

Answer 32

Orbitals which have the equivalent energy levels. s subshells contain 1 orbital, p subshells contain 3 orbitals, d subshells contain 5 orbitals

Question 33

Electron configuration

Answer 33

Shows how the electrons are arranged in the subshells

Question 34

Ionic bond

Answer 34

Electrostatic attraction between positive and negative ions

Question 35

Giant ionic lattices

Answer 35

Structure resulting from oppsoitely charges ions strongly attracted in all directions e.g. NaCl

Question 36

Covalent bond

Answer 36

The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

Question 37

Dative covalent bond

Answer 37

A shared pair of electrons where both electrons originated from the same atom

Question 38

Average bond enthalpy

Answer 38

A measurement of covalent bond strength. It’s the energy changes associated with breaking 1 mole of bonds in gaseous molecules

Question 39

Electron pair repulsion theory

Answer 39

The idea that electron pairs repel and so affect the shape of the particles. Non bonding pairs (lone pairs) repel more than bonded pairs

Question 40

Linear

Answer 40

Shapes caused by having 2 bonding pairs and 0 non bonding electron pairs, which repel as far as possible. Bond angle: 180°

Question 41

Non linear

Answer 41

Shape caused by having 2 bonding and 1/2 non bonding electron pairs which repel as far as possible. The non bonding pairs repel more than bonding pairs. Bond angle: 118°/104.5°

Question 42

Trigonal planar

Answer 42

Shape caused by having 3 bonding and 0 non bonding electron pairs which repel as far as possible. Bond angle: 120°

Question 43

Pyramidal

Answer 43

Shape caused by having 3 bonding and 1 non bonding electron pairs which repel as far as possible. The non bonding pairs repel more than bonding pairs. Bond angle: 107°

Question 44

Tetrahedral

Answer 44

Shape caused by having 4 bonding and 0 non bonding electron pairs which repel as far as possible. Bond angle: 109.5°

Question 45

Octahedral

Answer 45

Shape caused by having 6 bonding and 0 non bonding electron pairs which repel as far as possible. Bond angle: 90°

Question 46

Electronegativity

Answer 46

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

Question 47

Polar bond

Answer 47

A covalent bond in which there is a permanent dipole due to different electronegativites of the bonded atoms

Question 48

Dipole

Answer 48

Having a positive and a negative end

Question 49

Induced dipole

Answer 49

An instantaneous dipole caused by dipoles on neighbouring molecules

Question 50

London forces

Answer 50

Induced dipole-dipole interactions between molecules

Question 51

Hydrogen bond

Answer 51

Intermolecular bonding between molecules containing N, O or F and the H atom of -NH, -OH or HF