Classification of Matter and Thermal Energy Physical Science Ms. Fezza

Composition of Matter O Substances O Pure O Elements O Compounds

Elements O All the atoms are alike O Examples O Aluminum O Lead O Break down the elements into the smallest pieces O Still the same atoms

Compounds O Two or more elements O Chemically combined in fixed amounts O Cannot be separated by physical means O Different properties than their elements O Examples: O Salt O Water O Chalk

Mixtures O Two or more substances that can be separated by physical means O Heterogeneous O Homogeneous

Heterogeneous Mixture O Different substances remain distinct O Ex: Salad dressing O Suspensions O Liquid and solid particles that settle O Colloids O Particles that never settle O Ex: Milk, Paint, Air O Beam of light through it and you will see light as light scatters– Tyndall Effect

Homogeneous O Remains constantly and uniformly mixed O Particles so small they cannot be seen with a microscope O Particles will never settle O AKA Solution O Solids dissolved in liquids O Gases in solids or liquids

Compare and Contrast O Mixtures VS Substances

Physical Properties O Characteristics that you can observe without changing the identity of the substance O Examples: O Color O Shape O Size O Density O Melting point O Boiling Point

Appearance O How do you describe an object? O Color, volume, temperature, size, etc

Behavior O Ex: O Magnetic O Conductor/Insulator O Viscosity

Physical Separation O Separating iron and sand O Magnetic property becomes useful O Recycling

Physical Change O Physical changes- identity stays the same O Changes size, shape, or state of matter O The kind of substance does not change O Density, specific heat, and melting/boiling points stay the same O Can change states if it gains enough energy O This does not change the substance’s identity

Distillation O Getting fresh water from salt water O Uses boiling point O Evaporates liquid and recondenses it

Chemical Properties O Observations that result in one or more new substances O Flammability O Burning produces new substances O Reaction has occurred

Chemical Changes O Change from one substance to another O Identity changes O Smell changes O Rotten eggs O Rust O CLUES: O Heating or cooling O Formation of bubbles or solids in a liquid are indicators of a reaction

Using chemical changes O Tarnishing O Cleaning of the silver sulfide from the reaction with air

Weathering O Splitting of rocks from cracking, water fills the cracks and freezes and____________. Then the rock cracks O Physical O Chemical Weathering O Calcium carbonate reacting with carbon dioxide in water O Forms calcium bicarbonate O Icicle shaped rocks in caves

Law of Conservation of Mass O The mass present before a chemical change (reactants) equals the mass after the chemical change (products) O After a reaction, the total mass stays the same O Problems 7 and 8 Page 476

Thermal Energy O Matter is always in motion O What is the relationship between kinetic energy and temperature? O How are the molecules of an object colliding as they heat up? O Thermal energy is the sum of kinetic and potential energy of the particles

Thermal Energy and Temp. O Thermal Energy depends on temperature O As temperature increases, the thermal energy __________.

Mass and Thermal Energy O More mass means that there is more thermal energy (Thermal Energy is summative) O A glass of water or a bucket of water both at 30 degrees Celsius. Which has more Thermal Energy? O Why?

Heat O Heat is the energy that is transferred between objects due to a temperature difference between the objects O Warmer objects always heat cooler objects O REVERSE NEVER HAPPENS O How does heat flow when you take your temperature?