What are the three states of matter ?

The three states of matter are solid , liquid and gas . A substance can usually exist in all three states depending on temperature.

What is the particle model ? (Higher Tier Only)

The particle model is a simplified model that explains how matter changes state depending on the energy and forces present between particles. Particles are represented as small, solid, inelastic spheres.

How are particles arranged and how do they move in a solid ?

In a solid , particles are in a regular arrangement , very close together, and vibrate about a fixed position. They cannot move freely past each other.

Give four limitations of the particle model. (Higher Tier Only)

The four limitations of the particle model are: It assumes all particles are spherical, which is not always true It assumes particles are inelastic, which is not always true It does not account for forces of attraction between particles It does not accurately represent the size of particles relative to the space between them

In a liquid , particles are .......... arranged and .......... together, and they .......... around each other.

In a liquid , particles are randomly arranged and close together, and they move around each other.

True or False? The particle model accurately represents the forces of attraction between particles. (Higher Tier Only)

False. The particle model does not account for forces of attraction between particles. This is one of its key limitations.

How are particles arranged and how do they move in a gas ?

In a gas , particles are randomly arranged , far apart , and move quickly in all directions. There is a lot of empty space between them.

Why does the temperature remain constant during a change of state on a heating curve? (Higher Tier Only)

The temperature remains constant during a change of state because the heat energy supplied is used to break the forces between particles rather than increasing kinetic energy. Once all forces are broken, the temperature rises again.

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

False. Evaporation occurs at any temperature below the boiling point. It is a surface process where some particles have enough energy to escape as gas. Boiling is a different process that occurs throughout the liquid at a fixed temperature.

The particle model represents particles as small, solid, .......... spheres. It does not account for .......... between particles or the .......... of particles relative to the space between them. (Higher Tier Only)

The particle model represents particles as small, solid, inelastic spheres. It does not account for forces of attraction between particles or the size of particles relative to the space between them.

Define physical change .

A physical change is a change that does not alter the identity of a substance. The particles themselves remain the same, and the change is usually reversible.

How does the strength of forces between particles affect the energy needed to change state? (Higher Tier Only)

The stronger the forces between particles, the higher the energy needed for melting and boiling to occur. Substances with strong intermolecular forces have higher melting and boiling points.

State changes at the melting point : .......... (solid → liquid) and .......... (liquid → solid).

State changes at the melting point : melting (solid → liquid) and freezing (liquid → solid).

True or False? The particle model accurately represents the size of particles relative to the spaces between them. (Higher Tier Only)

False. The particle model does not accurately represent the size of particles relative to the space between them. In reality, particles are much smaller than the gaps between them.

Why are physical changes such as changes of state generally easy to reverse?

Physical changes are easy to reverse because no new substance is formed . Only the forces between particles change. The particles themselves stay the same, so the process can be undone by changing the temperature.

What happens to particles in a solid when it is heated, and why does it eventually melt? (Higher Tier Only)

When a solid is heated, its particles absorb thermal energy and vibrate more vigorously . As temperature increases, the vibrations become so large that the bonds between particles break, and the solid melts into a liquid.

Define chemical change .

A chemical change (or chemical reaction) is a change in which one or more substances are converted into different substances. The reactants are converted into products .

State changes at the boiling point : .......... (liquid → gas) and .......... (gas → liquid).

State changes at the boiling point : boiling (liquid → gas) and condensing (gas → liquid).

True or False? Individual atoms share the same properties as bulk matter.

False. Individual atoms do not share the same properties as bulk matter. Properties like melting point and conductivity emerge from large collections of atoms, not from individual atoms.

Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration . It occurs because particles are in constant random motion and provides evidence for the particle model.

GCSEChemistryOCRChemistry A (Gateway)Flashcards1. ParticlesThe Particle Model

The Particle Model (OCR GCSE Chemistry A (Gateway)): Flashcards

Exam code: J248

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FrontThe Particle Model
What are the three states of matter?

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Cards in this collection (20)

What are the three states of matter?
The three states of matter are solid, liquid and gas. A substance can usually exist in all three states depending on temperature.
What is the particle model? (Higher Tier Only)
The particle model is a simplified model that explains how matter changes state depending on the energy and forces present between particles. Particles are represented as small, solid, inelastic spheres.
How are particles arranged and how do they move in a solid?
In a solid, particles are in a regular arrangement, very close together, and vibrate about a fixed position. They cannot move freely past each other.
Give four limitations of the particle model. (Higher Tier Only)
The four limitations of the particle model are:
1. It assumes all particles are spherical, which is not always true
2. It assumes particles are inelastic, which is not always true
3. It does not account for forces of attraction between particles
4. It does not accurately represent the size of particles relative to the space between them
In a liquid, particles are .......... arranged and .......... together, and they .......... around each other.
In a liquid, particles are randomly arranged and close together, and they move around each other.
True or False?
The particle model accurately represents the forces of attraction between particles. (Higher Tier Only)
False.
The particle model does not account for forces of attraction between particles. This is one of its key limitations.
How are particles arranged and how do they move in a gas?
In a gas, particles are randomly arranged, far apart, and move quickly in all directions. There is a lot of empty space between them.
Why does the temperature remain constant during a change of state on a heating curve? (Higher Tier Only)
The temperature remains constant during a change of state because the heat energy supplied is used to break the forces between particles rather than increasing kinetic energy. Once all forces are broken, the temperature rises again.
True or False?
Evaporation only occurs at the boiling point of a liquid.
False.
Evaporation occurs at any temperature below the boiling point. It is a surface process where some particles have enough energy to escape as gas. Boiling is a different process that occurs throughout the liquid at a fixed temperature.
The particle model represents particles as small, solid, .......... spheres. It does not account for .......... between particles or the .......... of particles relative to the space between them. (Higher Tier Only)
The particle model represents particles as small, solid, inelastic spheres. It does not account for forces of attraction between particles or the size of particles relative to the space between them.
Define physical change.
A physical change is a change that does not alter the identity of a substance. The particles themselves remain the same, and the change is usually reversible.
How does the strength of forces between particles affect the energy needed to change state? (Higher Tier Only)
The stronger the forces between particles, the higher the energy needed for melting and boiling to occur. Substances with strong intermolecular forces have higher melting and boiling points.
State changes at the melting point:
.......... (solid → liquid) and .......... (liquid → solid).
State changes at the melting point:
melting (solid → liquid) and freezing (liquid → solid).
True or False?
The particle model accurately represents the size of particles relative to the spaces between them. (Higher Tier Only)
False.
The particle model does not accurately represent the size of particles relative to the space between them. In reality, particles are much smaller than the gaps between them.
Why are physical changes such as changes of state generally easy to reverse?
Physical changes are easy to reverse because no new substance is formed. Only the forces between particles change. The particles themselves stay the same, so the process can be undone by changing the temperature.
What happens to particles in a solid when it is heated, and why does it eventually melt? (Higher Tier Only)
When a solid is heated, its particles absorb thermal energy and vibrate more vigorously. As temperature increases, the vibrations become so large that the bonds between particles break, and the solid melts into a liquid.
Define chemical change.
A chemical change (or chemical reaction) is a change in which one or more substances are converted into different substances. The reactants are converted into products.
State changes at the boiling point:
.......... (liquid → gas) and .......... (gas → liquid).
State changes at the boiling point:
boiling (liquid → gas) and condensing (gas → liquid).
True or False?
Individual atoms share the same properties as bulk matter.
False.
Individual atoms do not share the same properties as bulk matter. Properties like melting point and conductivity emerge from large collections of atoms, not from individual atoms.
Define diffusion.
Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration. It occurs because particles are in constant random motion and provides evidence for the particle model.

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