Unit 2: Properties of Matter

Properties of Matter 4 Physical Properties: –can be observed or measured without changing the composition of matter –Examples: size, shape, color, phase ( solid, liquid, gas ) 4 Chemical Properties –How a substance changes into a new substance –examples: flammability, reacts with oxygen and burns.

Physical Properties 4 Mass – amount of matter 4 Weight – response of mass to pull of gravity –All mass has gravity – depends on size 4 Volume – space taken up by matter 4 Density – amount of mass in space (D=m/V)

Physical and Chemical Changes 4 Physical Changes: –No new substances are formed –Physical properties (or states) may change –Examples: dissolving, melting, evaporating, grinding, tearing 4 Chemical Changes: –One or more new substances with new and different properties are formed –Examples: smoking, burning, bubbling, lose or gain heat, color change

States (or phases) of matter: 1. Solid 2. Liquid 3. Gas 4. Plasma -state depends on the motion of the particles in the sample

Kinetic theory of matter: -all matter is made up of tiny particles that are constantly in motion

Particles are on the move... The speed of the particles determines the temperature and the state of the matter.

Solids: - definite shape - definite volume -particles are held close together - particles vibrate back and forth - particles have the least amount of kinetic energy -particles are sometimes arranged as crystals

Solids If we could use “magic glasses” to see the molecules in ice, we would see organized crystals where particles vibrate in place and are “attached” to each other.

Crystal: - A solid with a distinctive shape because its atoms are arranged in repeating geometric patterns - Examples: -salt crystals are cubic -snowflakes are water crystals in the shape of a hexagon

Amorphous solids: -Solids that are not made up of crystals -Examples: -glass -wax -some plastics

Liquids: - No definite shape - Definite volume -particles are separated -particles have more kinetic energy than solids but less than gasses -Viscosity: resistance (how easy) to flow

Liquids Using “magic glasses” in liquid water, you would see molecules moving around each other and moving within their allowed volume.

Gases: - No definite shape - No definite volume -particles are far apart -particles have more kinetic energy than liquids and solids

Gases Using magic glasses on water vapor, we would see water molecules Flying wildly around at high rates of speed bumping other molecules To the point where they are pushed out of the way to create a bubble.

Plasmas(sun): - No definite shape - No definite volume -Most kinetic energy

Change of State Solids Liquids Gases To change the state of matter, energy is added or released.

Melting Matter changes from a solid to a liquid. Energy is needed or added to the matter. As energy is added, particles move faster. Some particles have enough energy to escape the crystal structure and escape to become a liquid. The energy needed to change a solid to a liquid is: Heat of Fusion = H f H f = 80 cal/g or 334 J/g for water.

Vaporization or boiling Matter changes from a liquid to a gas. Energy is needed or added to the matter. As energy is added, particles move faster. Some particles have enough energy to escape the attraction and change into a gas. The energy needed to change a liquid to a gas is: Heat of Vaporization = H v H v = 540 cal/g or 2260 J/g for water. Sublimation – Matter changes from a solid to a gas. Energy Is needed or added. Dry ice is a good example of sublimation.

Cooling Processes Condensation – the reverse of evaporation. Heat of Vaporization energy is released into the environment (H v = 540 cal/g). This makes The environment warmer. Freezing – the reverse of melting. Heat of Fusion energy is released into the Environment (H f = 80 cal/g). This also makes the environment warmer.

Calculating Energy To calculate the energy needed to change Ice to steam: (calculate Q or energy) to melt ice: Q f = m x H f to heat the water: Q h = m x  T to boil water: Q v = m x H v Then add them together to get the total heat.