States of Matter and Their Changes

Solids have a fixed shape and volume because particles are closely packed in a regular arrangement.
Liquids have a fixed volume but not a fixed shape because particles are close together but can move around each other.
Gases have no fixed shape or volume because particles are far apart and move freely in all directions.

Increasing the mass of a substance increases the force of attraction between particles. This makes it harder for particles to move around, resulting in a more rigid state.

Brownian motion is the random movement of particles suspended in a fluid.
Diffusion is the movement of particles from an area of high concentration to an area of low concentration.
Both processes are driven by the kinetic energy of particles.

The changes of state are reversible, meaning they can occur in both directions.
The amount of energy required to change state depends on the strength of the intermolecular forces between the particles.

A heating and cooling curve shows the relationship between temperature and time for a substance as it is heated or cooled.
The curve has plateaus where the temperature remains constant even though heat is being added or removed. This indicates the phase change is occurring.

A mixture is a combination of two or more substances that are not chemically bonded.
A pure substance is a substance that is made up of only one type of atom or molecule.
Compounds are pure substances that consist of two or more elements chemically bonded together.

A solution is a homogeneous mixture containing a solute (the substance being dissolved) and a solvent (the substance doing the dissolving).
A colloid is a heterogeneous mixture where particles are larger than in a solution but smaller than in a suspension.
A soluble substance will dissolve in a solvent.

Filtration: Separates solids from liquids using a filter.
Evaporation: Separates a dissolved solid from a liquid by heating the mixture.
Distillation: Separates liquids with different boiling points by heating and cooling the mixture.
Chromatography: Separates components of a mixture based on their different affinities for a stationary phase.

Solids: Have a fixed shape and volume. Particles are tightly packed and vibrate in fixed positions.
Liquids: Have a fixed volume but take the shape of their container. Particles are closer together than in gases but can move around.
Gases: Have no fixed shape or volume. Particles are far apart and move freely.

Higher mass: Leads to stronger intermolecular forces, making it more difficult for particles to move. This results in substances being more likely to be solids at room temperature.
Lower mass: Leads to weaker intermolecular forces, making it easier for particles to move. This results in substances being more likely to be liquids or gases at room temperature.

Brownian motion: The random movement of particles suspended in a fluid (liquid or gas). This movement is caused by collisions with the molecules of the fluid.
Diffusion: The movement of particles from a region of high concentration to a region of low concentration. This movement is driven by the tendency of particles to spread out evenly.

Changes in state are caused by changes in temperature and pressure.
Heating provides energy to the particles, increasing their kinetic energy and causing them to move faster. This can lead to a change in state from solid to liquid to gas.
Cooling removes energy from the particles, decreasing their kinetic energy and causing them to move slower. This can lead to a change in state from gas to liquid to solid.

Heating Curve: A graph that shows the temperature of a substance as it is heated over time.
Cooling Curve: A graph that shows the temperature of a substance as it is cooled over time.
During changes in state, the temperature remains constant even though heat is being added or removed. This is because the energy is being used to break or form intermolecular bonds.
A dynamic equilibrium exists when the rate of the forward and reverse reactions are equal. For example, during a change in state, the rate of melting and freezing is the same.

Mixture: A combination of two or more substances that are not chemically bonded. Components can be separated using physical methods.
Pure substance: A substance that is made up of only one type of particle.
Compound: A substance formed when two or more elements are chemically combined. Cannot be separated by physical means.

Solution: A homogenous mixture where one substance (solute) dissolves in another substance (solvent). The solute particles are evenly distributed.
Colloid: A heterogeneous mixture where particles are dispersed in a medium but are large enough to be seen with a microscope. Particles do not settle out.
Solvent: The substance that dissolves the solute.

Homogenous mixture: A mixture where the components are evenly distributed throughout the mixture. Example: Saltwater.
Heterogeneous mixture: A mixture where the components are not evenly distributed throughout the mixture. Example: Sand and water.

Distillation: Separating liquids with different boiling points by heating and collecting the vapors.
Filtration: Separating a solid from a liquid using a filter paper.
Evaporation: Separating a dissolved solid from a liquid by heating the solution to its boiling point and allowing the liquid to evaporate.
Chromatography: Separating components of a mixture based on their different affinities for the stationary phase and mobile phase.
Magnetic separation: Separating magnetic materials from a mixture.
Decantation: Separating a liquid from a solid by carefully pouring off the liquid.
Crystallization: Separating a solid from a solution by cooling the solution to the point where the solid crystallizes out.