Polyatomic
ions
Nitrate
- Valency of -1 Sulfate
- NO3 - SO4 2-
- Valency 2-
Hydroxide
- OH - Ammonium
- Valency of -1 - NH4
- Valency 1+
Carbonate
- CO3
- Valency 2-
The particle nature of
matter
- State the distinguishing properties of solids, liquids and gases
Solids
- Strong forces of attraction between particles, particles are packed very closely
together in a fixed and regular pattern
- Atoms vibrate in position but can’t change position or move
- Solids have a fixed volume, shape and high density
Liquids
- Weaker attractive forces in liquids than in solids, particles are close together in an
irregular, unfixed pattern.
- Particles can move and slide past each other which is why liquids adopt the shape of
the container they’re in and also why they are able to flow.
- Liquids have a fixed volume but not a fixed shape and have a moderate to high
density.
Gases
- No intermolecular forces, particles are in random movement and so there is no
defined pattern
- Particles are far apart and move quickly (around 500 m/s) in all directions, they
collide with each other and with the sides of the container (this is how pressure is
created inside a can of gas)
, - No fixed volume, since there is a lot of space between the particles, gases can be
compressed
- Describe the structure of solids, liquids and gases in terms of particle separation,
arrangement and types of motion
-
- Describe changes of state in terms of melting, boiling, evaporation, freezing,
condensation and sublimation
Melting
- Melting is when a solid changes into a liquid
- Requires heat energy which transforms into kinetic energy, allowing the particles to
move
- Occurs at a specific temperature known as the melting point (m.p.) which is unique to
each pure solid
Boiling
- Boiling is when a liquid changes into a gas
- Requires heat which causes bubbles of gas to form below the surface of a liquid,
allowing for liquid particles to escape from the surface and within the liquid
- Occurs at a specific temperature known as the boiling point (b.p.) which is unique to
each pure liquid
Freezing
- Freezing is when a liquid changes into a solid
, - This is the reverse of melting and occurs at exactly the same temperature as melting,
hence the melting point and freezing point of a pure substance are the same. Water
for example freezes and melts at 0ºC
- Requires a significant decrease in temperature (or loss of thermal energy) and
occurs at a specific temperature which is unique for each pure substance
Evaporation
- When a liquid changes into a gas. Evaporation occurs only at the surface of liquids
where high energy particles can escape from the liquid’s surface at low temperatures,
below the b.p. of the liquid
- The larger the surface area and the warmer the liquid/surface, the more quickly a
liquid can evaporate
- No heat is required and evaporation occurs over a range of temperatures
Condensation
- When a gas changes into a liquid, usually on cooling. When a gas is cooled its
particles lose energy and when they bump into each other they lack the energy to
bounce away again, instead they group together to form a liquid
- No energy is required for condensation to occur and it takes place over a range of
temperatures
Sublimation
- When a solid changes directly into a gas
- This happens to only a few solids such as iodine or solid carbon dioxide
- The reverse reaction also happens and is also called sublimation (sometimes called
deposition or desublimation)
- Sublimation occurs at a specific temperature which is unique for a pure substance
, - Explain changes of state in terms of the kinetic theory
Changes in State & Kinetic Theory
- When substances are heated, the particles absorb thermal energy which is converted
into kinetic energy. This is the basis of the kinetic theory of matter
- Heating a solid causes its particles to vibrate more and as the temperature increases,
they vibrate so much that the solid expands until the structure breaks and the solid
melts
- On further heating, the now liquid substance expands more and some particles at the
surface gain sufficient energy to overcome the intermolecular forces and evaporate
- When the b.p. temperature is reached, all the particles gain enough energy to escape
and the liquids boils
- These changes in state can be shown on a graph which is called a heating curve
- Cooling down a gas has the reverse effect and this would be called a cooling curve
- These curves are used to show how changes in temperature affect changes of state
ions
Nitrate
- Valency of -1 Sulfate
- NO3 - SO4 2-
- Valency 2-
Hydroxide
- OH - Ammonium
- Valency of -1 - NH4
- Valency 1+
Carbonate
- CO3
- Valency 2-
The particle nature of
matter
- State the distinguishing properties of solids, liquids and gases
Solids
- Strong forces of attraction between particles, particles are packed very closely
together in a fixed and regular pattern
- Atoms vibrate in position but can’t change position or move
- Solids have a fixed volume, shape and high density
Liquids
- Weaker attractive forces in liquids than in solids, particles are close together in an
irregular, unfixed pattern.
- Particles can move and slide past each other which is why liquids adopt the shape of
the container they’re in and also why they are able to flow.
- Liquids have a fixed volume but not a fixed shape and have a moderate to high
density.
Gases
- No intermolecular forces, particles are in random movement and so there is no
defined pattern
- Particles are far apart and move quickly (around 500 m/s) in all directions, they
collide with each other and with the sides of the container (this is how pressure is
created inside a can of gas)
, - No fixed volume, since there is a lot of space between the particles, gases can be
compressed
- Describe the structure of solids, liquids and gases in terms of particle separation,
arrangement and types of motion
-
- Describe changes of state in terms of melting, boiling, evaporation, freezing,
condensation and sublimation
Melting
- Melting is when a solid changes into a liquid
- Requires heat energy which transforms into kinetic energy, allowing the particles to
move
- Occurs at a specific temperature known as the melting point (m.p.) which is unique to
each pure solid
Boiling
- Boiling is when a liquid changes into a gas
- Requires heat which causes bubbles of gas to form below the surface of a liquid,
allowing for liquid particles to escape from the surface and within the liquid
- Occurs at a specific temperature known as the boiling point (b.p.) which is unique to
each pure liquid
Freezing
- Freezing is when a liquid changes into a solid
, - This is the reverse of melting and occurs at exactly the same temperature as melting,
hence the melting point and freezing point of a pure substance are the same. Water
for example freezes and melts at 0ºC
- Requires a significant decrease in temperature (or loss of thermal energy) and
occurs at a specific temperature which is unique for each pure substance
Evaporation
- When a liquid changes into a gas. Evaporation occurs only at the surface of liquids
where high energy particles can escape from the liquid’s surface at low temperatures,
below the b.p. of the liquid
- The larger the surface area and the warmer the liquid/surface, the more quickly a
liquid can evaporate
- No heat is required and evaporation occurs over a range of temperatures
Condensation
- When a gas changes into a liquid, usually on cooling. When a gas is cooled its
particles lose energy and when they bump into each other they lack the energy to
bounce away again, instead they group together to form a liquid
- No energy is required for condensation to occur and it takes place over a range of
temperatures
Sublimation
- When a solid changes directly into a gas
- This happens to only a few solids such as iodine or solid carbon dioxide
- The reverse reaction also happens and is also called sublimation (sometimes called
deposition or desublimation)
- Sublimation occurs at a specific temperature which is unique for a pure substance
, - Explain changes of state in terms of the kinetic theory
Changes in State & Kinetic Theory
- When substances are heated, the particles absorb thermal energy which is converted
into kinetic energy. This is the basis of the kinetic theory of matter
- Heating a solid causes its particles to vibrate more and as the temperature increases,
they vibrate so much that the solid expands until the structure breaks and the solid
melts
- On further heating, the now liquid substance expands more and some particles at the
surface gain sufficient energy to overcome the intermolecular forces and evaporate
- When the b.p. temperature is reached, all the particles gain enough energy to escape
and the liquids boils
- These changes in state can be shown on a graph which is called a heating curve
- Cooling down a gas has the reverse effect and this would be called a cooling curve
- These curves are used to show how changes in temperature affect changes of state
