Physical changes occur when objects change but do not change into a difference substance. A physical change involves a change in physical properties. Examples of physical properties include: texture, shape, size, color, odor, volume, mass, weight, and density. Examples of physical change are shape, size, state(phase), and mixture (solute into solvent).

Solute – a substance dissolved into another substance (solvent). Ex. Food coloring, salt

Solvent- a substance, solid, liquid, or gas that dissolves another solid, liquid, or gas. Ex: water

Solution-a mixture of a solute and a solvent that are mixed to the molecular level.

Thermal Expansion of SolidsTemperature- the average kinetic energy of

its particles.Thermal energy-the total kinetic energy of

the particles of a sample.Thermal expansion- the increase in size of

an object due to the increase in temperature.

The size of a solid, liquid, or gas depends on how hot or cold it is.

Hot = bigger and cold = smaller.

Examples are railroad tracks expanding because of the heat of a hot summer day or concrete squares of a road getting bigger because the day is hot.

Volume-is the amount of space a substance fills.Volume relates to Thermal Expansion because

thermal expansion involves an increase in volume.

The particles of matter are like the following: In gas the particles are far apart. In liquid the particles are close together but still fluid. In a solid the particles are bunched tightly together.

*Gas particles bounce against each other and the side of the container keeping it in the shape of the bottle.

*Gas particles contract when cold and cannot keep the bottle in shape. The air on the outside of the bottle presses the bottle shrinking it.

*The gas particles have a lot of energy and force the bottle to expand outward with the increased pressure.

*The greater the temperature the greater the pressure. The lower the temperature the lower the pressure.

Pressure-the amount of force exerted in a per unit area.

When gas particles in a flexible bottle have more pressure and thus more volume, they hit the side of the container more and more often expanding the bottle.

When gas particles are put into a less flexible container or when they are pumped into an area of limited space such as a basketball or a tire the pressure increases and the volume decreases.As pressure decreases volume increases.See the chart to the right.

There are three main states of matter: Solids where atoms are densely packed

together. Liquids where atoms have more energy

and are farther apart than a solid and more fluid.

Gases where atoms have a lot of energy, move around quickly, and are very far apart.

Review the chart here.

Freezing-particles losing energy (heat) and bunching together tightly.

Melting-particles gaining energy (heat) and moving away from each other becoming fluid.

Vaporization- particles in a liquid gaining energy (heat) enough to change from a liquid to a gas.

Condensation- particles losing energy (heat) and coming together to form a liquid.

Sublimation-the process in which a solid becomes a gas without first turning into a liquid.

Water freezes at 32oF(0oC) & boils at 212oF(100oC)