Why does a substance with stronger forces between its particles have a higher melting point ?

A stronger force between particles requires more energy to overcome. This means a higher temperature is needed to give the particles enough energy to move around each other, so the melting point is higher.

In a solid, particles are arranged in a .......... pattern, are .......... together, and .......... about fixed positions.

In a solid, particles are arranged in a regular pattern, are very close together, and vibrate about fixed positions.

True or False? Gas particles are regularly arranged and vibrate about fixed positions.

False. Gas particles are randomly arranged with large gaps between them and move quickly in all directions . It is solid particles that vibrate about fixed positions in a regular arrangement .

What is the difference between boiling and evaporation ?

Boiling occurs at a specific temperature (the boiling point) and involves bubbles of gas forming inside the liquid. Evaporation occurs over a range of temperatures and only at the surface of the liquid, where high-energy particles escape.

What is sublimation ?

Sublimation is the process by which a solid changes directly into a gas without passing through the liquid state. Examples include iodine and solid carbon dioxide .

Condensation occurs when a .......... changes into a .......... on cooling, and takes place at a single temperature for a .......... substance.

Condensation occurs when a gas changes into a liquid on cooling, and takes place at a single temperature for a pure substance.

Why is a change of state described as a physical change ?

A change of state is a physical change because the particles themselves remain unchanged. Only the forces between particles change. They weaken on heating and strengthen on cooling.

True or False? Particles in a liquid are randomly arranged and move around each other.

True. Unlike solids , where particles vibrate about fixed positions in a regular arrangement , liquid particles are randomly arranged and move around each other , which is why liquids can flow.

What happens to the particles of a solid when it melts ?

When a solid melts, particles absorb heat energy which is used to overcome the forces between particles . The particles break free from their fixed positions and begin to move around each other as a liquid. During melting, the temperature stays constant because the energy is used to break forces, not to increase the speed of particles.

True or False? The freezing point of a pure substance is the same temperature as its melting point.

True. Freezing is the reverse of melting and occurs at the same temperature. For example, water freezes and melts at 0 °C.

Diffusion is the movement of particles from a region of high concentration to a region of low concentration , due to the random motion of particles. It requires no energy input.

Diffusion happens .......... at higher temperatures because particles have more .......... energy and move more quickly.

Diffusion happens faster at higher temperatures because particles have more kinetic energy and move more quickly.

True or False? Diffusion requires an input of energy to move particles from high to low concentration.

False. Diffusion is a spontaneous process that requires no energy input . Particles move from high to low concentration due to their natural random motion .

Why does diffusion occur faster in gases than in liquids ?

In a gas, particles are far apart and move quickly in all directions , so they mix more easily. In a liquid, particles are closer together and move more slowly, so diffusion is slower.

Dilution is the process of adding more .......... to a solution. This .......... the concentration of the solute and spreads the particles further .......... .

Dilution is the process of adding more solvent to a solution. This decreases the concentration of the solute and spreads the particles further apart .

True or False? Dilution removes solute particles from a solution.

False. Dilution does not remove particles. It spreads them out by adding extra solvent. The solute is still present but at a lower concentration.

Why does a coloured solution become paler when diluted?

Adding more solvent spreads out the solute particles, so fewer are present in any given volume. The colour appears paler because the coloured particles are less concentrated, but they are not destroyed.

True or False? Both diffusion and dilution provide evidence that matter is made of tiny, moving particles.

True. In diffusion , particles spread out spontaneously. In dilution , particles remain present but become more spread out as solvent is added. Both results are explained by kinetic particle theory .

A solution is formed when a solute dissolves in a .......... . The dissolved substance is the .......... and the dissolving liquid is the .......... .

A solution is formed when a solute dissolves in a solvent . The dissolved substance is the solute and the dissolving liquid is the solvent .

What is a saturated solution ?

A saturated solution is a solution that contains the maximum amount of solute that can be dissolved in the solvent at a given temperature. No more solute can dissolve.

True or False? A saturated solution can dissolve more solute if more is added.

False. A saturated solution already holds the maximum amount of dissolved solute . Any additional solute added will remain undissolved.

What is the difference between a soluble and an insoluble substance?

A soluble substance dissolves in a solvent to form a solution. An insoluble substance does not dissolve in the solvent. For example, salt is soluble in water but sand is insoluble.

In sea water, the water acts as the .......... and the dissolved salt acts as the .......... .

In sea water, the water acts as the solvent and the dissolved salt acts as the solute .

True or False? A solution is a type of mixture where the solute is evenly distributed.

True. A solution is a homogeneous mixture formed when a solute dissolves in a solvent . The solute particles are evenly spread throughout the solvent.

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States of Matter (Edexcel IGCSE Science (Double Award): Chemistry): Flashcards

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FrontThe Three States of Matter
Why does a substance with stronger forces between its particles have a higher melting point?

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Why does a substance with stronger forces between its particles have a higher melting point?
A stronger force between particles requires more energy to overcome. This means a higher temperature is needed to give the particles enough energy to move around each other, so the melting point is higher.
In a solid, particles are arranged in a .......... pattern, are .......... together, and .......... about fixed positions.
In a solid, particles are arranged in a regular pattern, are very close together, and vibrate about fixed positions.
True or False?
Gas particles are regularly arranged and vibrate about fixed positions.
False.
Gas particles are randomly arranged with large gaps between them and move quickly in all directions. It is solid particles that vibrate about fixed positions in a regular arrangement.
What is the difference between boiling and evaporation?
Boiling occurs at a specific temperature (the boiling point) and involves bubbles of gas forming inside the liquid. Evaporation occurs over a range of temperatures and only at the surface of the liquid, where high-energy particles escape.
What is sublimation?
Sublimation is the process by which a solid changes directly into a gas without passing through the liquid state. Examples include iodine and solid carbon dioxide.
Condensation occurs when a .......... changes into a .......... on cooling, and takes place at a single temperature for a .......... substance.
Condensation occurs when a gas changes into a liquid on cooling, and takes place at a single temperature for a pure substance.
Why is a change of state described as a physical change?
A change of state is a physical change because the particles themselves remain unchanged. Only the forces between particles change. They weaken on heating and strengthen on cooling.
True or False?
Particles in a liquid are randomly arranged and move around each other.
True.
Unlike solids, where particles vibrate about fixed positions in a regular arrangement, liquid particles are randomly arranged and move around each other, which is why liquids can flow.
What happens to the particles of a solid when it melts?
When a solid melts, particles absorb heat energy which is used to overcome the forces between particles. The particles break free from their fixed positions and begin to move around each other as a liquid. During melting, the temperature stays constant because the energy is used to break forces, not to increase the speed of particles.
True or False?
The freezing point of a pure substance is the same temperature as its melting point.
True.
Freezing is the reverse of melting and occurs at the same temperature. For example, water freezes and melts at 0 °C.
What is diffusion?
Diffusion is the movement of particles from a region of high concentration to a region of low concentration, due to the random motion of particles. It requires no energy input.
Diffusion happens .......... at higher temperatures because particles have more .......... energy and move more quickly.
Diffusion happens faster at higher temperatures because particles have more kinetic energy and move more quickly.
True or False?
Diffusion requires an input of energy to move particles from high to low concentration.
False.
Diffusion is a spontaneous process that requires no energy input. Particles move from high to low concentration due to their natural random motion.
Why does diffusion occur faster in gases than in liquids?
In a gas, particles are far apart and move quickly in all directions, so they mix more easily. In a liquid, particles are closer together and move more slowly, so diffusion is slower.
Dilution is the process of adding more .......... to a solution. This .......... the concentration of the solute and spreads the particles further ...........
Dilution is the process of adding more solvent to a solution. This decreases the concentration of the solute and spreads the particles further apart.
True or False?
Dilution removes solute particles from a solution.
False.
Dilution does not remove particles. It spreads them out by adding extra solvent. The solute is still present but at a lower concentration.
Why does a coloured solution become paler when diluted?
Adding more solvent spreads out the solute particles, so fewer are present in any given volume. The colour appears paler because the coloured particles are less concentrated, but they are not destroyed.
True or False?
Both diffusion and dilution provide evidence that matter is made of tiny, moving particles.
True.
In diffusion, particles spread out spontaneously. In dilution, particles remain present but become more spread out as solvent is added. Both results are explained by kinetic particle theory.
A solution is formed when a solute dissolves in a .......... . The dissolved substance is the .......... and the dissolving liquid is the .......... .
A solution is formed when a solute dissolves in a solvent. The dissolved substance is the solute and the dissolving liquid is the solvent.
What is a saturated solution?
A saturated solution is a solution that contains the maximum amount of solute that can be dissolved in the solvent at a given temperature. No more solute can dissolve.
True or False?
A saturated solution can dissolve more solute if more is added.
False.
A saturated solution already holds the maximum amount of dissolved solute. Any additional solute added will remain undissolved.
What is the difference between a soluble and an insoluble substance?
A soluble substance dissolves in a solvent to form a solution. An insoluble substance does not dissolve in the solvent. For example, salt is soluble in water but sand is insoluble.
In sea water, the water acts as the .......... and the dissolved salt acts as the ...........
In sea water, the water acts as the solvent and the dissolved salt acts as the solute.
True or False?
A solution is a type of mixture where the solute is evenly distributed.
True.
A solution is a homogeneous mixture formed when a solute dissolves in a solvent. The solute particles are evenly spread throughout the solvent.

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