Properties of Matter Matter: anything that has mass and takes up space Substance: matter that has a uniform and unchanging composition. An element is a substance that has only one kind of atom. Gold A compound is a substance that has two or more types of atoms in fixed proportions. Water (H 2 O)

Substances are identified by their... Physical and Chemical properties

Substances are identified by their... Physical and Chemical properties

Physical properties can be observed and measured WITHOUT permanently changing the material. Observable physical properties: Color, shape, hardness, odor, texture state of matter (solid, liquid or gas) luster (how light reflects off of it)

Measurable physical properties: Density-mass contained in 1 mL of material Melting point-Temperature at which material begins to melt Freezing point-Temperature at which material begins to freeze Boiling point-Temperature at which material begins to boil

Chemical properties can only be observed or measured by PERMANENTLY CHANGING the material. Examples: Flammability, toxicity (how poisonous it is), acidity, radioactivity, reactivity with oxygen, light sensitivity

Physical ChangeChemical Change meltingLight or flame given off boiling Color/odor change evaporating dissolving Forming a solid freezing Temperature change grinding Gas bubbles formed cutting

Chemical or physical change? 1. When heated, a substance goes from a liquid to a gas. 2. When heated, the color of a substance changes from blue to white. 3. When heated, a substance burns. PHYSICAL! CHEMICAL!

Chemical or physical change? 4. When hit with a hammer, a substance explodes. 5. When hit with a hammer, a substance flattens. 6. When hit with a hammer, a substance breaks apart into smaller pieces. CHEMICAL! PHYSICAL!

Chemical or physical change? 7. When water is added to a blue liquid, it changes to a lighter blue. 8. When a clear liquid is added to a blue liquid, a white solid is formed. 9. When water is added to a blue liquid, it forms a blue layer and a clear layer. PHYSICAL! CHEMICAL! PHYSICAL!

Indicators of chemical change A color change Gas evolution (bubbles) Precipitate (solid) formation Temperature change Energy given off (light or flames)

Mixture: a combination of two or more substances. The composition of mixtures is variable. Uh oh!

Heterogeneous mixture: a mixture in which the physical properties are different in different parts of the mixture. heterogeneous Homogeneous mixture: a mixture in which the physical properties are the same throughout. A solution soluble dye

Types of solutions Gas/gas Gas/liquid Liquid/liquid Solid/liquid Solid/solid Air is 78% N 2 and 21% O 2 Carbonated sodas are made by dissolving CO 2 gas in water 8 carat gold is a solid solution of Cu, Ag and Au Vinegar is 5% acetic acid, 95% water Sports drinks are 0.1% NaCl, 5% sugar and 94.9% water.

Colloids: very small particles are suspended in solution Gold/silver alloy particles in glass Water droplets in air

Tyndall Effect: Scattering of light off of colloidal particles No Tyndall effect = not a colloid

Separating Mixtures Mixtures can be separated by taking advantage of differences in physical properties. Filtration: a porous barrier is used to separate a solid from a liquid. The filter can only separate out particles of solid that are LARGER than the pores through the filter.

Distillation: separation of substances by differences in boiling point. The substance with the lower boiling point will distill off first.

Crystallization: formation of a pure solid substance from a solution containing the dissolved substance. Sodium acetate in water p-dichlorobenzene in chloroform