S1.1 Introduction to the Particulate Nature of Matter

What happens to particles during melting in terms of energy?

During melting, particles absorb thermal energy which is converted into kinetic energy, allowing them to move more freely.

What is the relationship between temperature and kinetic energy during melting?

During melting, temperature remains constant while energy is used to break bonds between particles, with no increase in kinetic energy.

State what is meant by the term element.

An element is a substance made of atoms that all contain the same number of protons and cannot be split into anything simpler.

True or False? Nitrogen is an element.

True. Nitrogen is an element.

True or False? Water is an element.

False. Water is a compound composed of hydrogen and oxygen atoms chemically combined.

State what is meant by the term compound.

A compound consists of atoms of different elements chemically bonded together in a fixed ratio.

True or False? Compounds can be separated into their elements by physical means.

False. Compounds cannot be separated into their elements by physical means.

What is a mixture?

A mixture contains more than one element or compound in no fixed ratio, which are not chemically bonded.

What is the difference between a compound and a mixture?

A compound consists of two or more elements that are chemically combined, while a mixture consists of two or more substances that are not chemically combined.

True or False? All substances can be classified as elements, compounds, or mixtures.

True. All substances can be classified into one of these three types.

Classify the following as an element, compound, or mixture: Air, Ammonia (NH3), Chlorine (Cl2), Copper sulfate (CuSO4).

Air = mixture; Ammonia, NH3 = compound; Chlorine, Cl2 = element; Copper sulfate, CuSO4 = compound.

What is the difference between an element and a compound?

An element consists of only one element, while a compound consists of two or more elements that are chemically combined.

Is a copper wire an element or compound?

Copper wire is an element.

Why is copper sulfate not on the Periodic Table?

Copper sulfate is not in the Periodic Table because it is a compound / not an element.

Define the term homogeneous mixture.

A homogeneous mixture is a mixture with a uniform composition and properties throughout.

True or False? Air is an example of a heterogeneous mixture.

False. Air is an example of a homogeneous mixture.

A mixture that has a non-uniform composition and different properties throughout is called a __________ mixture.

A heterogeneous mixture.

Is concrete an example of a heterogeneous or homogeneous mixture?

Concrete is an example of a heterogeneous mixture.

What does simple distillation separate?

Simple distillation is used to separate: • a liquid and soluble solid from a solution (e.g., water from a solution of salt water) • a pure liquid from a mixture of liquids.

State what is meant by the term simple distillation.

Simple distillation is a technique used to separate a liquid from a solution by boiling the solution and condensing the vapour.

What is fractional distillation?

Fractional distillation is a technique used to separate two or more liquids that have different boiling points from a mixture.

Which technique separates solutions with more than one type of dissolved solid (solute)?

Chromatography.

What does filtration separate?

Filtration separates an undissolved solid from a mixture of solid and liquid.

What is crystallisation used for?

Crystallisation is used to separate a dissolved solid from a solution.

In terms of the solid (solute), what is important about the solvent used for recrystallisation?

It is important that the solid (solute) is more soluble in hot solvent than in cold.

What is paper chromatography used for?

Paper chromatography is used to separate substances that have different solubilities in a given solvent, such as identifying the components of a mixture.

True or False? In filtration, the filtrate is the solid left behind on the filter paper.

False. In filtration, the residue is the solid left behind on the filter paper. The filtrate is the liquid that passes through the filter.

What is recrystallisation used for?

Recrystallisation is used to purify impure solids.

Why can two liquids be separated using distillation?

Liquids can be separated using distillation because they have different boiling points.

What is the principle behind recrystallisation?

Recrystallisation uses a hot solvent to dissolve both the organic solid and impurities; as the solution cools, the solid crystallises out and leaves the impurities in solution.

Name the state change that takes place when a liquid becomes a solid.

Freezing.

What is boiling?

Boiling is when a liquid changes into a gas at a constant temperature.

What type of energy allows particles to move in the liquid state?

Kinetic energy.

True or False? Energy is needed to change a gas to a liquid.

False. Energy is released when a gas changes into a liquid.

What is melting?

Melting is when a solid changes into a liquid.

True or False? The melting point and freezing point of a substance are the same.

True. There is no difference between melting point and freezing point.

What is freezing?

Freezing is when a liquid changes into a solid.

What happens to the forces of attraction when a solid turns to a liquid?

They are overcome or broken.

What is condensation?

Condensation is when a gas changes into a liquid, usually on cooling.

What is evaporation?

Evaporation is when a liquid changes into a gas.

State the melting and boiling point of pure water.

Melting point = 0 °C; Boiling point = 100 °C.

True or False? Evaporation only occurs at the boiling point of a liquid.

False. Evaporation occurs below boiling point over a range of temperatures.

What happens to particles during melting in terms of energy?

Particles absorb thermal energy which is converted into kinetic energy, allowing them to move more freely.

What is the relationship between surface area and evaporation rate?

The larger the surface area, the faster the evaporation.

What is the main difference in particle movement between solids and liquids?

In solids, particles vibrate in position but cannot change location. In liquids, particles move and slide past each other.

Which state of matter has particles with the highest energy?

Gas.

What does (s) represent in a chemical equation?

Solid state.

What does (g) represent in a chemical equation?

Gaseous state.

What does (aq) represent in a chemical equation?

Aqueous (dissolved in water).

True or False? Changes of state are chemical changes.

False. Changes of state are physical changes.

What is deposition?

Deposition is the change of a substance from a gas to a solid.

Define the term sublimation.

Sublimation is the change of a substance from a solid directly into a gas.

Define absolute zero.

Absolute zero is the lowest possible temperature (0 K or -273.15 °C), where atoms and molecules have zero kinetic and potential energy.

True or False? All particles of different substances at the same temperature have the same velocity.

False. Particles may have the same average kinetic energy but different velocities due to mass.

What is the relationship between temperature and kinetic energy during melting?

Temperature stays constant; energy is used to break bonds between particles, not to increase kinetic energy.

What happens to particle movement as temperature increases?

As temperature increases, particle movement increases, giving higher average kinetic energy.

What is 300 K in degrees Celsius?

27 °C (300 - 273).

True or False? A change in temperature of 1 K is equal to a change of 1 °C.

True.

50 °C in Kelvin is _____.

323 K.

True or False? There is no change in temperature during a change of state.

True.