Density an object’s mass per unit volume units:

Toothpaste Electricity A star Juice Sound The ocean Fear Peanut butter Saliva Helium Democracy Car exhaust Gasoline Paper Bacteria A cell Wisdom Heat Dog Wind Atoms Soil DNA Clouds batteries

Directions Classify these words into TWO groups. Give a name to each group. Add one more example to each group. Raise your hand when you are done.

Matter and Changes

matter: has volume (takes up space), and mass can be solid, liquid or gas

chemistry: the study of matter and changes to matter

physical change: the chemical composition (makeup or parts) of the matter stays the same. Ex: state changes (solid to liquid to gas), changing shape (ripping, squishing)

chemical change: a compound’s chemical composition (makeup) is changed – it becomes a new substance ex: burning, rusting, reacting

Chemical or Physical Change? burning paper folding a piece of paper the reaction of KI and Pb(NO3)2 combustion of gasoline hammering gold into a ring cutting a diamond acid rain “melting” a statue a pile of old iron rusting separating water into H and O by using electricity

Which of the following is an example of a chemical change? A. Ice cracking B. Sugar dissolving C. Milk souring D. Lead melting

Which of these describes a pollution-producing process that involves only a physical change? A. Coal with a high sulfur content is burned, producing gases that cause acid rain. B. Chlorofluorocarbons are released, changing ozone in the upper atmosphere into oxygen. C. Hot wastewater is discharged into a lake, lowering oxygen levels in the water. D. Nitrogen oxide emissions combine with water vapor, producing nitric acid.

Which of the following processes is an example of a physical change associated with an oak tree? A. Decomposition of bark by bracket fungi. B. Starches and sugars being broken down during energy production. C. Water and carbon dioxide being converted to glucose. D. Evaporation of water from the surface of the leaves.

Which of the following represents a physical property? a. Copper tarnishes to green when weathered. b. Oxygen is flammable when ignited. c. Iron rusts when exposed to oxygen. d. Ice melts if left at room temperature.

Write down one unique example of a physical change you see at school.

Write down one unique example of a chemical change you see in your neighborhood.

Water

H2O

Ice

Dihydrogen monoxide

TAKES SHAPE AND VOLUME OF CONTAINER! FIXED VOLUME FIXED SHAPE States of Matter low temperatures high temperatures slow particle movement fast particle movement TAKES SHAPE AND VOLUME OF CONTAINER! FIXED VOLUME NO FIXED SHAPE FIXED VOLUME FIXED SHAPE Solid Liquid Gas

State Shape Volume Den-sity Particle motion Forces solid liquid gas definite (fixed) definite high slight vibration liquid not definite medium gas low, varia-ble very, very fast

Which state… Fixed volume and shape No fixed shape and no fixed volume Fixed volume but no fixed shape Takes the shape and size of its container Takes the shape, but not the size of its container

Which state… Can be squeezed (compressed) into a smaller space? Exists at a low temperature? Has medium particle motion? Has particles that just vibrate a little bit?

States of Matter and Transitions (Phases) SOLID SUBLIMATION FREEZING MELTING DEPOSITION EVAPORATION LIQUID GAS CONDENSATION

Why does temperature change the state of a sample of matter? Kinetic Theory: all matter is made of particles that are always moving. Temperature: a measurement of Kinetic Energy (oC, K) 0 Kelvin: absolute zero: no particle movement 200 K is twice the particle movement of 100 K Kinetic energy can overcome bond forces

low kinetic energy (KE) high kinetic energy (KE) Solid Liquid Gas

Bond forces hold particles together. Kinetic energy may be great enough to break bonds between particles (in a gas)

State Shape Volume Density Particle motion Forces solid liquid gas definite (fixed) definite high slight vibration Greater than KE liquid not definite medium Similar to KE gas low, varia-ble very, very fast Much less than KE

What transition? Ice turns into water Water turns into steam Water turns into ice Water vapor (gas) turns into rain in clouds Water boils and turns to steam An ice cube looks like it’s making steam! Cream and sugar turns into ice cream. Snow turns into water vapor.

Which state… Has the lowest Kinetic Energy? Has very strong bond forces? Has the highest Kinetic Energy? Has bonds that are broken most easily? Has bond forces similar to its Kinetic Energy?