Module 1 (Properties of Matter)

Question 1

Solution

Separation Methods

Answer 1

Utilises property of solubility.

A mixture of two solids which have significantly different solubilities can be entirely mixed into a solvent and some constituents will dissolve more readily.

The procedure must be performed with filtration, evaporation or crystallisation in order to remove the solvent afterwards.

Question 2

Magnetic Separation

Separation Methods

Answer 2

Utilises property of magnetism.

By inserting the magnet into the mixture of different sized solids and moving it around, the particles with magnetism will attach to the magnet.

This may need to be done multiple times and/or other particles may come up with the magnetic ones, such as powder.

Question 3

Crystallisation

Separation Methods

Answer 3

Utilises property of solubility in cold water.

A substance’s solubility in cold water can also be utilised where the entire mixture is dissolved in hot water.

The solution will then begin to cool, one substance crystallising sooner, while the other is left dissolved.

The solid components can then be separated through a method of filtration.

Question 4

Filtration

Separation Methods

Answer 4

Utilises property of particle size.

When the mixture is passed through a screen, often filter paper, undissolved solid particles of a larger particle size are unable to pass through, collecting above the screen while the liquid filtrate passes through.

Question 5

Evaporation

Separation Methods

Answer 5

Utilises property of boiling point.

A mixture consisting of two materials, one of which has a higher boiling point, can be put over a heat source, where one substance will evaporate more readily, leaving the other behind.

Used to collect the solid solute of a solution.

Question 6

Distillation

Separation Methods

Answer 6

Utilises property of boiling point.

While this utilises boiling point similarly to evaporation, distillation separates the liquids with the use of a condenser to capture and cool the vapour to condense it back into a liquid distillate in another container.

Used to collect the liquid solvent of a solution.

Separation Methods

Question 7

Fractional Distillation

Separation Methods

Answer 7

The method and setup are similar to distillation but this involves the separation of more than two liquids by utilizing their specific boiling points.

The setup includes evaporation and the use of a condenser, but the temperature of the original mixture must be monitored in order to ensure that the final distillate is composed of one substance only.

Question 8

Gas Chromotography

Separation Methods

Answer 8

Chromatography is effective in disclosing the individual components of a gas mixture by passing the entirety of the mixture through a glass or metal column.

The components can be detected and recorded due to the particle frequency at which they travel.

Question 9

Sieving

Separation Methods

Answer 9

Utilises the property of particle size.

A sieve, whose size of netting must be chosen in accordance with the mixture, utilises particle size to allow the smaller particles to fall through the holes while the larger particles are unable to pass through the gaps and can then be transferred into another container.

Question 10

Sedimentation

Separation Methods

Answer 10

Utilises the property of particle density.

Solid particles will eventually settle at the bottom of the liquid it is combined with due to gravity in that the solid particles have a higher density than the liquid, allowing them to settle towards the bottom of the container as sediment.

Question 11

Decantation

Separation Methods

Answer 11

Utilises the property of particle density.

This can be performed after sedimentation caused by particle density and is simply pouring off the liquid that is now sitting above the sediment.

Question 12

Centrifugation

Separation Methods

Answer 12

Utilises the property of particle density.

While this utilises particle density similarly to sedimentation, it occurs more rapidly through the use of a centrifuge, which is a spinning mechanism that will cause higher density substances to gravitate towards the edges while lower density substances gravitate towards the axis due to centrifugal force.

Question 13

Linear (2)

Molecular Shapes

Answer 13

Two atoms

Question 14

Linear (3)

Molecular Shapes

Answer 14

Three atoms.

No lone pairs on the central atom.

Question 15

Bent/Angular (with Single Bonds)

Molecular Shapes

Answer 15

Three atoms.

Two sets of lone pairs on the central atom.

Question 16

Bent/Angular (with Single and Double Bond)

Molecular Shapes

Answer 16

Three atoms.

One set of lone pairs on the central atom.

Question 17

Trigonal Pyramidal

Molecular Shapes

Answer 17

Four atoms.

One set of lone pairs on the central atom.

Question 18

Trigonal Planar

Molecular Shapes

Answer 18

Four atoms.

No lone pairs on the central atom.

Question 19

Tetrahedral

Molecular Shapes

Answer 19

Five atoms.

Four bonds on the central atom and no lone pairs.

Question 20

Homogenous Mixture

Answer 20

A mixture with equal concentration of all components throughout.

Question 21

Heterogenous Mixture

Answer 21

A mixture with a composition that is not uniform.

Question 22

Mineral

Gravimetric Analysis

Answer 22

A naturally-occurring solid element or compound with a definite composition/range of compositions e.g. quartz (silicone + oxygen)

Question 23

Rock

Gravimetric Analysis

Answer 23

Made up of two or more minerals.

Question 24

Ore

Gravimetric Analysis

Answer 24

Concentrations of minerals in rocks that are economically viable for extraction.

Question 25

Yield

Gravimetric Analysis

Answer 25

The quantity (often in %) of material recovered from an ore after it has been processed.

Question 26

Uses of Gravimetric Analysis

Three main uses

Answer 26

1. To measure the amount of mineral in an ore deposit to determine it if is worth extracting
2. To measure pollutant chemical quantities in water/air
3. To determine soil composition to see if it is suitable for growing crops

Question 27

Physical Properties of Metals

6

Answer 27

Lustrous

Malleable

Ductile/Tensile

Dense

High melting/boiling point

High conductivity of heat/electricity

Question 28

Physical Properties of Non-Metals

6

Answer 28

Dull

Not malleable

Not ductile

Not dense

Low melting/boiling point

Poor conductivity of heat/electricity

Question 29

Reactivity with Water

Chemical Properties

Answer 29

Group 1 alkali metals react vigorously with water to form hydroxides and hydrogen gas.

Question 30

Reactivity with Oxygen

Chemical Properties

Answer 30

Group 2 alkaline earth metals react with oxygen to form metal oxides.

Question 31

Electronegativity (EN)

Chemical Properties

Answer 31

A numerical measure of the electron-attracting power of the atom within a covalent bond. An atom’s ability to attract electrons. Increases diagonally from bottom left to top right.

0-1.7 → covalent bond
>1.7 → ionic bond

Question 32

Ionisation Energy

Chemical Properties

Answer 32

An atom’s ability to remove an electron from the electrostatic force of the positive nucleus.

Elements with low ionisation energy tend to lose electrons readily and form cations.

Question 33

Isotopes

Answer 33

Same protons, different neutrons.

Stable isotopes have a balanced number of protons and neutrons.
Unstable isotopes have an imbalance in the number of protons and neutron, leading to nuclear instability and radioactive decay.

Question 34

The Schrodinger Atomic Model

Answer 34

Electrons occupy orbitals instead of shells.

Each shell is spearated into subshells and each subshell into orbitals.

s subshell = 1 orbital
p subshell = 3 orbitals
d subshell = 5 orbitals
f subshell = 7 orbitals

Question 35

Pauli Exclusion Principle

Subshell Notations

Answer 35

Each orbital can contain a maximum of 2 electrons. Each electron has a different spin.

Question 36

Aufbau Principle

Subshell Notations

Answer 36

The lowest energy orbitals are always filled with electrons first.

Question 37

Hund’s Rule

Subshell Notations

Answer 37

Every orbital in a subshell must be filled with one electron with the same spin before an orbital is filled with a second electron.

Question 38

Relative Atomic Mass

Answer 38

The average mass of an element’s isotopes, weighted by their natural abundance.

Ar = ∑(Isotopic Mass × Abundance) / 100

Question 39

Emission Spectrum

Bohr Model

Answer 39

An emission spectrum is produced when heated atoms give off electromagnetic radiation (light), producing a number of coloured lines on a black background. Each line corresponds to a light of different energy (red = lowest, violet = highest).

After an element has absorbed energy, it rapidly reurns to its original energy level and drops down to its original electron shell, releasingthe energy as light.

Proves that subshells have different energy levels.

Question 40

Absorption Spectrum

Bohr Model

Answer 40

An absorption spectrum is produced when atoms absorb electromagnetic radiation, producing a number of black lines on a coloured background. Each line corresponds to a light of different energy (red = lowest, violet = highest).

When an element is heated, the electrons absorb the energy and briefly jump to the next shell.

Proves that subshells have different energy levels.

Question 41

Alpha Decay

Types of Radiation

Answer 41

Process:

1. The nucleus of an atom splits into 2 parts.
2. One part (the α particle, consisting of 2 protons and 2 neutrons or a helium nucleus) goes zooming off into space.
3. The nucleus left behind has its atomic number reduced by 2, and mass number reduced by 4 (by the 2 protons and 2 neutrons).

Properties:

• Very low penetration power, can be stopped by a sheet of paper, human skin, or a few centimetres of air.
• Very high ionising ability, meaning that they can remove electrons from atoms or molecules to create ions.

Question 42

Beta Minus

Types of Radiation

Answer 42

Occurs when the nucleus has too many neutrons compared to protons.

Process:

1. The nucleus breaks down, converting a neutron → proton
2. During this conversion, an electron (the β particle) is ejected from the nucleus and goes zooming off into space
3. The nucleus left behind has its atomic number increased by 1 (because it gained a proton) but the mass number remains the same (since the total number of protons and neutrons hasn’t changed; it lost a neutron but gained a proton)

Properties:

• Much lighter than alpha particles
• Moderate penetration power. Beta particles are stopped by a few mm of aluminium or plastic
• Moderate ionising ability

Neutron → Proton + Electron (β-) + Antineutrino.

Question 43

Beta Plus/Positron Emission

Types of Radiation

Answer 43

Occurs when the nucleus has too many protons compared to neutrons

Process:

1. Inside the nucleus, a proton → neutron
2. During this conversion, a positron (the positive counterpart of an electron) and neutrino are created
3. The positron (β+particle) is ejected from the nucleus and goes zooming off into space
4. The nucleus left behind has its atomic number reduced by 1 (because it lost a proton), but the mass number remains the same (since the total number of protons and neutrons hasn’t changed; it lost a proton but gained a neutron)

Properties:

• Much lighter than alpha particles
• Moderate penetration power. Beta particles are stopped by a few mm of aluminium or plastic
• Moderate ionising ability

Proton → Neutron + Positron (β+) + Neutrino.

Question 44

Gamma Radiation

Types of Radiation

Answer 44

Process:

1. After a nucleus undergoes alpha or beta decay, it might be in an excited energy state
2. To return to a stable state, the nucleus releases excess energy in the form of a high-energy photon, a gamma ray
3. The gamma ray goes zooming off into space
4. The nucleus left behind has the same atomic and mass number as before, but is now in a lower energy state

Properties:

• Very high penetration power, can pass through several cm of lead or metres of concrete
• Low ionising power per interaction

Question 45

States of Matter at Room Temperature

Periodicity

Answer 45

Elements in the same group often share the same state of matter at room temperature (25°C).

Across periods, elements typically start as gases on the right and become solids moving left.

Question 46

Electron Configuration and Atomic Radii

Periodicity

Answer 46

Down a group, elements have the same number of valence electrons but in higher energy levels, further from the nucleus (more shells). Atomic radium increases down a group.

Across a period, the number of electrons increases in the same energy level, leading to more protons in the nucleus and pulling the electrons closer. Atomic radium decreases across a period.

Question 47

First Ionisation Energy and Electronegativity

Periodicity

Answer 47

First ionisation energy decreases down a group because the outer electrons are further from the nucleus and more shielded by inner electrons. Electronegativity also decreases down a group due to increasing atomic size and shielding.

Increases across periods for both ionisation energy and electronegativity as nuclear charge increases, holding electrons more tightly.

Question 48

Reactivity with Water

Periodicity

Answer 48

Alkali metal reactivity increases down a group as the atomic radium increases, making it easier to lose the outer electron. Alkaline earth metals show the same trend but are less reactive than Group 1.

Metals are generally less reactive with water across periods as metals become less metallic and more nonmetallic.

Question 49

Lewis Dot Diagrams

Answer 49

1. Determine the central atom
   
   • The atom further to the right on the Periodic Table is generally an outer atom.
   • Hydrogens and halogens are almost always OUTER atoms.
2. Arrange outer atoms around central atom
3. Count up valence electrons
4. Draw a bond between each outer atom and the central atom. Count the atoms you’ve used and minus them from your total valence electrons
5. Use the remaining electrons to fill octets around the outer atoms
6. Now that all outer atoms have octets, fix up the central atom for an octet. Outer atoms may have electron pairs etc.

Question 50

Electronegativity Difference in Polar and Non-Polar Bonds

Answer 50

0.5-1.7 difference: covalent polar. More electronegative atom is slightly negatively charged and vice versa, as electrons are attracted to the atom with greater electronegativity.

Less than 0.5 difference: covalent non-polar.

Question 51

Allotropy

Answer 51

The existence of two or more different physical forms of the same element within the same physical state. These different forms, called allotropes, have distinct structures and properties, even though they are composed of the same element.

Allotropes differ in their arrangements of atoms or molecules, meaning their properties vary.

Question 52

Diamond

Carbon Allotropes

Answer 52

Structure: Each carbon atom is tetrahedrally bonded to four other carbon atoms in a 3D lattice.

Properties: Extremely hard, high melting point, transparent, and a good insulator.

Uses: Cutting tools, jewelry.

Question 53

Graphite

Carbon Allotropes

Answer 53

Structure: Each carbon atom is bonded to three others in flat layers or sheets, with weak forces between layers.

Properties: Soft, slippery, conductive of electricity, opaque.

Uses: Lubricants, pencils, electrodes.

Question 54

Graphene

Carbon Allotropes

Answer 54

Structure: A single layer of carbon atoms arranged in a hexagonal lattice.

Properties: Extremely strong, lightweight, excellent conductor of electricity and heat.

Uses: Electronics, nanotechnology.

Question 55

Fullerenes

Carbon Allotropes

Answer 55

Structure: Carbon atoms arranged in a hollow sphere (buckyballs), ellipsoid, or tube (carbon nanotubes).

Properties: Varies, but can be very strong, conductive, and have unique chemical properties.

Uses: Nanotechnology, medicine, materials science.

Question 56

Dioxygen (O2)

Oxygen Allotropes

Answer 56

Structure: Two oxygen atoms bonded together (double bond).

Properties: Colorless, odorless gas at room temperature, essential for respiration.

Uses: Breathing, combustion, industrial processes.

Question 57

Ozone (O3)

Oxygen Allotropes

Answer 57

Structure: Three oxygen atoms bonded together in a bent structure.

Properties: Pale blue gas with a strong odor, much less stable than O₂, powerful oxidizing agent.

Uses: Disinfection, ozone layer protection, industrial applications.

Question 58

Ionic Bonding Model

Answer 58

Large numbers of cations and anions combine to form a 3D lattice, held together strongly by the electrostatic attractive forces between the oppositely charged ions, called ionic bonding.

Question 59

Electrical Conductivity

Ionic Network

Answer 59

In the solid form, ionic compounds do not conduct electricity because the ions in the crystal lattice are not free to move. This makes ionic compounds useful for insulators.

When solid ionic compounds melt, the ions become free to move, enabling the cations and anions to conduct electricity. When an electric current is applied to either a molten ionic compound or a solution of the compound in water, positive ions move towards the negatively charged electrode, and negative ions move towards the positively charged electron, resulting in an electric current.

Electrolyte: solution or molten substance that conducts electricity by the movement of ions

Question 60

Melting/Boiling Point

Ionic Network

Answer 60

Ionic compounds have high melting points that indicate that the forces between the particles are strong, so a large amount of energy is needed to overcome the electrostatic attraction between the oppositely-charged ions to allow them to move freely.

Question 61

Hardness/Brittleness

Ionic Network

Answer 61

The strong electrostatic forces of attraction between ions in an ionic compound mean that a strong force is needed to disrupt the crystal lattice.

Although crystals are hard, they will shatter under a strong force, because it causes layers of ions to move relative to one another. Ions of like charge are shifted so that they are next to each other, resulting in repulsion that causes the crystals to shatter, which is why they are brittle.

Question 62

Solubility

Ionic Network

Answer 62

Some ionic compounds are very soluble in water but some are very insoluble.

Whether an ionic compound is soluble or insoluble depends on the relative strength of the forces of attraction between the positive and negative ions in the lattice, and the water molecules and the ions.

Question 63

Covalent Network

Answer 63

Contains neutral non-metal or semi-metal atoms bonded by convalent bonds in 3 dimensions.

Question 64

Electrical Conductivity

Covalent Network

Answer 64

No delocalised electrons makes majority of covalent networks insulators.

The exception is graphite, which has covalent bonds confined to 2D parallel planes, so delocalised electrons allow graphite electrical conductivity.

Question 65

Melting Point

Covalent Network

Answer 65

Strong covalent bonds hold the atoms together in the network.

Question 66

Hardness

Covalent Network

Answer 66

Strong covalent bonds hold the atoms together in the network.

Question 67

Graphite

Covalent Network

Answer 67

There are weak dispersion forces between the layers. Graphite is thus hard in one direction but slippery and soft in another direction. The weak intermolecular forces between graphite’s 2D parallel planes hold the structure together, and hence graphite powder is used as a dry lubricant.

Question 68

Diamond

Covalent Network

Answer 68

Brittle and does not conduct electricity because it has no freely moving charged particles.

Thermal conductivity is very high because atoms are held together very strongly.

No small molecules in diamond, so no weak forces between atoms = high sublimation point.

Only strong covalent bonds, no weak intermolecular forces present = hardest naturally occurring mineral known.

Question 69

Silicon Dioxide (Silica)

Covalent Network

Answer 69

Silica also exists as a continuous 3D covalent network structure. Each silicone atom is at the centre of a tetrahedron and is covalently bonded to four oxygen atoms. Each oxygen atom is bonded to 2 silicone atoms.

Silica is hard, has a high melting point and does not dissolve in water or organic solvents due to the strong covalent bonding between the silicone and oxygen atoms.

Question 70

Covalent Molecular

Answer 70

Contain individual molecules arranged in a pattern within the crystal lattice.

The atoms within each molecule are bonded covalently but the forces between each molecule involve weak intermolecular attractions.

Question 71

Brittle and Soft

Covalent Molecular

Answer 71

Weak intermolecular forces between each molecule

Question 72

Melting Point

Covalent Molecular

Answer 72

Weak intermolecular forces between each molecule break easily.

Question 73

Electrical Conductivity

Covalent Molecular

Answer 73

Absence of mobile charge carriers means that they do not conduct in the solid or liquid state.

Question 74

Metallic Bonding Model

Answer 74

Positive ions/cations are arranged in a closely packed 3D lattice, occupying fixed positions.

Sea of delocalised electrons from the outer shells of atoms belong to the lattice as a whole but can move freely throughout the lattice.

Cations are held in the lattice by the electrostatic attractive force between the cations and the delocalised electrons.

Does not explain the range in melting points, hardness and densities of different metals; the differences in electrical conductivities; and the magnetic nature of metals such as cobalt, iron, and nickel.

Question 75

Melting/Boiling Point

Metallic Structure

Answer 75

Delocalised electrons make the forces between the particles in the element are very strong.

Question 76

Electrical Conductivity

Metallic Structure

Answer 76

Metals are good conductors of electricity in both the solid and molten liquid states, because metals have freely-moving charged particles.

Question 77

Malleability/Ductility

Metallic Structure

Answer 77

Attractive forces between particles are stronger than the repulsive forces between the particles, when layers of particles are shifted.

Question 78

Heat Conductivity

Metallic Structure

Answer 78

Metals are good conductors of heat because energy is quickly transferred throughout the metal object.

When delocalised electrons bump into one another and into the metal ions, they transfer energy to each other. Heating a metal gives the ions and electrons more energy and causing them to vibrate faster, transmitting this energy rapidly throughout the lattice by the freely moving electrons.

Question 79

Lustrous

Metallic Structure

Answer 79

Refers to how light interacts with the surface of a crystal, mineral, or rock.

Metals, for example, are lustrous or reflective, meaning that free electrons are present, allowing for metals to reflect light of all wavelengths and appear shiny.

Question 80

Ion-Ion Interactions

Intermolecular Forces

Answer 80

Large ionic solids are held together by these strong intermolecular forces.

They have formal charges, and the interactions are between formally charged ions.

Question 81

Ion-Dipole

Intermolecular Forces

Answer 81

A side of the molecule with some electron excess and deficiency.

Question 82

Dipole-Dipole Forces

Intermolecular Forces

Answer 82

Ppolar molecules attract one another or other polar molecules.

The slightly positive end of one molecule will attract the slightly negative end of another. The presence of dipole-dipole attraction creates some ordering of molecules in the liquid and solid states.

The melting and boilign points of such molecules is higher than similar weight non-polar molecules, because of the increased attraction.

Question 83

Dispersion Forces

Intermolecular Forces

Answer 83

Non-polar molecules must attract one another, otherwise they couldn’t be condensed to form liquids/solids.

All covalent molecular sustances attract one another by weak intermolecular forces called dispersion forces, which arise due to the the formation of temporary dipoles between atoms and molecules.

Question 84

Temporary Dipoles

Intermolecular Forces

Answer 84

Caused by fluctuating electron distributions in atoms.

The heavier an atom/molecule, the larger the dispersion forces between neighbouring atoms.

Question 85

Hydrogen Bonds

Intermolecular Forces

Answer 85

A strong intermolecular force that arises from a type of polar attraction, the strongest intermolecular force. [FINISH]