Module 3 Periodicity

Question 1

D block

Answer 1

The part of the periodic table in which the element have their highest energy electron in the d orbital

Question 2

p-block

Answer 2

the part of the periodic table in which the elements have their highest energy
electron in a p-orbital

Question 3

s-block

Answer 3

the part of the periodic table in which the elements have their highest energy
electron in an s-orbital

Question 4

First ionisation energy

Answer 4

The removal of one mole of electrons from one mole of gaseous atoms. Factors which affect the first ionisation energy are: the strength of attraction between the electron and the nucleus, the nuclear charge and the atomic radius. There is a small decrease in first ionisation energy due to s- and p-subshell energies (between Be and B) and p-orbital repulsion.

Question 5

Electron configuration

Answer 5

The arrangement of electrons into orbitals and energy levels around the nucleus of an atom.

Question 6

Giant covalent lattice

Answer 6

A network of atoms connected by strong covalent bond. Giant covalent lattices typically insoluble with a high melting and boiling point due to the presence of strong covalent bonds. They are also poor electrical conductors as they don’t contain mobile charges particles.

Question 7

Metallic Bonding

Answer 7

strong electrostatic attraction between cations and delocalised electrons.

Question 8

Giant Metallic Lattice Structure

Answer 8

the structure of all metals, made up of cations and delocalised electrons. Giant metallic structures are typically insoluble with a high melting and boiling points due to strong electrostatic forces of attraction between cations and electrons.
Metals are good electrical conductors due to the presence of delocalised electrons.

Question 9

Periodicity

Answer 9

a repeating trend in physical and chemical properties across the periods of the
periodic table

Question 10

Successive Ionisation Energies

Answer 10

the energy required to remove each electron one-by-one
from one mole of gaseous atoms / ions

Question 11

Electron Configuration

Answer 11

the arrangement of electrons into orbitals and energy levels around
the nucleus of an atom/ ion. Group 2 elements have an s2
outer shell electron configuration

Question 12

First Ionisation Energy

Answer 12

the removal of one mole of electrons from one mole of gaseous
atoms. Factors which affect the first ionisation energy are: the strength of attraction between the electron and the nucleus, the nuclear charge and the atomic radius.

Question 13

Group 2 Oxide

Answer 13

a compound with the general formula MO, where M is a group 2 element.
When group 2 oxides react with water, they form an alkaline solution, with alkalinity increasing down the group.

Question 14

Second Ionisation Energy

Answer 14

the removal of one mole of electrons from one mole of gaseous
1+ ions to form one mole of 2+ ions

Question 15

Boiling Point

Answer 15

the temperature at which a liquid boils and becomes a gas. Boiling point
increases down group 7 due to the increasing strength of London Forces between the halogen molecules

Question 16

Diatomic Molecules

Answer 16

molecules that are made up of 2 atoms. Halogens are diatomic

Question 17

Displacement Reaction

Answer 17

a reaction in which one atom is replaced by another. Halogens can
undergo displacement reactions as their reactivity decreases down the group. The more reactive halogen will displace the less reactive halogen from a solution of its salt.

Question 18

Disproportionation

Answer 18

the oxidation and reduction of the same element. Examples include the
water treatment (reacting chlorine with water) and bleach formation (reacting chlorine with cold, dilute aqueous sodium hydroxide)

Question 19

Precipitation Reaction:

Answer 19

a reaction in which two aqueous solutions are combined to form an
insoluble salt (a precipitate). Halide anions undergo precipitation reactions with aqueous silver ions

Question 20

Water Treatment

Answer 20

the addition of chlorine to water to kill bacteria. The risks associated with
the use of chlorine to treat water are the hazards of toxic chlorine gas and the possible risks from the formation of chlorinated hydrocarbons

Question 21

Carbonate

Answer 21

a salt containing the CO3 2- anion. A reaction between a carbonate and H+ will form CO2

Question 22

Ammonium Ion

Answer 22

an ion with the formula NH4+ The test for ammonium ions is a reaction with warm NaOH, which forms NH3

Question 23

halides

Answer 23

a salt containing a group 7 anion. Cl-, Br-and I- can be tested for using a solution of
silver ions as this reaction forms a coloured precipitate. The solubility of the precipitate is then tested using dilute and concentrated ammonia

Question 24

Qualitative Analysis

Answer 24

identifies the elements present in a substance, typically using
test-tube reactions

Question 25

Sulfate

Answer 25

a salt containing the anion SO4 2-. A reaction between SO4 2- and Ba2+(aq) will form a precipitate

Question 26

Activation Energy

Answer 26

the minimum energy required for a reaction to take place.

Question 27

Average Bond Enthalpy

Answer 27

the energy required to break one mole of gaseous bonds. Actual bond enthalpies may differ from the average as the average bond enthalpy considers a particular bond in a range of molecules

Question 28

Endothermic

Answer 28

a reaction which takes in energy (ΔH is positive). More energy is required to break bonds than is released by making bonds.

Question 29

Exothermic

Answer 29

a reaction which gives out energy (ΔH is negative). More energy is released by bond making than is used in bond breaking

Question 30

Enthalpy (H)

Answer 30

a value that represents the heat content of a system.

Question 31

Enthalpy Change (ΔH)

Answer 31

the change in the heat content of a system during a reaction. This can be determined from experimental results using q = mcΔT (where q is the heat change of the surroundings, m is the mass of the surroundings, c is the specific heat capacity and ΔT is the change in temperature) ΔH=q/mols

Question 32

Enthalpy Change of Combustion (ΔcH)

Answer 32

the enthalpy change that takes place when one mole of a substance is completely combusted

Question 33

Enthalpy Change of Formation (ΔfH)

Answer 33

the enthalpy change that takes place when one mole of a compound is formed from its elements.

Question 34

Enthalpy Change of Neutralisation (ΔneutH)

Answer 34

the enthalpy change that takes place when one mole of water is formed from a neutralisation reaction

Question 35

Enthalpy Change of Reaction (ΔrH)

Answer 35

the enthalpy change that is associated with a particular chemical equation.

Question 36

Enthalpy Profile Diagram

Answer 36

shows the difference in the enthalpy of reactants and products as well as the activation energy of a reaction.

Question 37

Hess’ Law

Answer 37

the enthalpy change of a reaction is independent of the route it takes.

Question 38

Standard Conditions

Answer 38

a pressure of 100 kPa and a temperature of 298K

Question 39

Standard State

Answer 39

the physical state (s, l, g, aq) of a substance under standard conditions

Question 40

Boltzmann Distribution

Answer 40

a graph showing the distribution of the energies of molecules in relation to the activation energy. Increasing temperature will increase the proportion of molecules with energy above the activation energy. A catalyst lowers the activation energy meaning more molecules will have sufficient energy to reac

Question 41

Catalyst

Answer 41

a substance that speeds up the rate of a reaction without being used up. A catalyst allows the reaction to proceed via a different route with a lower activation energy. Catalysts are important in terms of economics and sustainability as they enable processes to take place at lower temperatures meaning less energy is required

Question 42

Collision Theory

Answer 42

the theory which states that molecules must collide with sufficient energy at the correct orientation for a reaction to occur.

Question 43

Concentration

Answer 43

the amount of a substance that is dissolved per unit volume of solution. Increasing the concentration increases the rate of reaction as there are more molecules in the same volume meaning more frequent successful collisions

Question 44

Enthalpy Profile Diagram

Answer 44

shows the difference in the enthalpy of reactants and products as well as the activation energy of a reaction

Question 45

Heterogeneous Catalyst

Answer 45

a catalyst that is in a different state to the reactants (e.g. a solid catalyst with gaseous reactants)

Question 46

Homogeneous catalyst

Answer 46

a catalyst which is in the same state as the reactants

Question 47

Pressure

Answer 47

the force that a gas exerts on the walls of a container. Increasing the pressure increases the rate of reaction as there are more molecules in the same volume (or the same number of molecules in a smaller volume) meaning more frequent successful collisions.

Question 48

Rate of Reaction

Answer 48

a measure of how quickly a reactant is used up/ a product is formed. Rate can be determined by measuring concentration, the volume of gas produced or the mass lost over time

Question 49

Compromise

Answer 49

balancing several different factors in order to get the best possible outcome. In industry, the position of the equilibrium and rate of reaction must be considered when deciding the conditions for the reaction. These factors must also be balanced with safety and economics.

Question 50

Dynamic Equilibrium:

Answer 50

a closed system in which the rates of the forward and reverse reactions are equivalent. The concentrations of reactants and products don’t change.

Question 51

Homogeneous Equilibrium

Answer 51

an equilibrium in which all reactants are in the same state.

Question 52

Le Chatelier’s Principle

Answer 52

when a system in dynamic equilibrium is subject to change, the position of equilibrium will shift to minimise the change. This principle is used to determine the effect of changing pressure, temperature or concentration on the position of equilibrium.

Question 53

KC

Answer 53

the equilibrium constant that is equal to the concentration of products raised to their stoichiometric coefficients divided by the concentration of reactants to the power of their stoichiometric coefficients. When KC is greater than 1, the equilibrium favours the products. When KC is less than 1, the equilibrium favours the reactants

Question 54

Enthalpy of formation equation

Answer 54

Reaction energy= (sum of)products - (sum of)reactants

Question 55

Enthalpy of combustion equation

Answer 55

Reaction energy=(sum of) reactants - (sum of) products