2.1

Classification of Matter Pure Substance - has a defined composition and cannot be separated into simpler substances by physical means. Each substances has a fixed, uniform composition. 2.1

Pure Substances Compounds - consist of atoms chemically combined together Elements - substance composed of only one type of atom 2.1

Pure Substances ELEMENTS Cannot be broken down into simpler substances. Can be found as solids, liquids, or gases Represented by symbols COMPOUNDS 2 more elements chemically joined together Can be broken down through chemical means Represented by a formula

Elements International symbols First 1-2 distinguishing letters in the name Symbols derived from non-English names : AntimonySbstibiumpotassium Kkalium Copper Cucuprumsilver Agargentum Gold Auaurumsodium Nanatrium Iron Feferrumtin Snstannum Lead Pbplumbumtungsten Wwolfram Mercury Hg hydragyrum 2.1

Compound Is composed of 2 or more different elements joined in a fixed proportions. Is a compound of Sodium and Chlorine The properties of a compound are different from those of the substances from which they are made. 2.1

Mixtures Mixtures - are impure matter Mixture - is composed of more than one element and or compound. The percentage composition varies from sample to sample. Components are chemically different and retain properties in a mixture do not melt/boil at a definite temperature 2.1

Types of Mixtures A homogeneous mixture has the same composition compounds throughout. Also called a solution. A heterogeneous mixture has different compositions and properties throughout. Sand 2.1

Solution Solution-homogeneous mixture where all components are of the same phase Air N 2 and O 2, Salt Water NaCl and H 2 O, White Gold Au and Pd They do not separate into distinct layers over time. The particles are too small to settle out, be trapper by a filter or scatter light. 2.1

Suspension “Shake well before using” Suspension-heterogeneous mixture in which the different components are in different phases Milk (water, solid proteins), Blood (water, solid proteins), Fog (air, tiny water droplets) The particles will settle out to the bottom of the container, will be trapped by a filter and will scatter light. 2.1

Colloids Homogenized milk is a colloid. Fog is a colloid. Contains particles that are intermediate in size. Like a solution, colloids will not separate into layers and you cannot filter it. The particles will scatter light. 2.1

Physical Properties Properties that can be observed and measured without changing the composition of the substance Color State of MatterSolid, liquid or gas Melting and Boiling Point Solubility Density Metallic Character Electrical Conductivity Thermal Conductivity Magnetic Properties MalleabilityEase of deformation ViscosityEase of flow 2.2

Viscosity The resistance to flowing The viscosity of a liquid usually decreases with heating. Water has a low viscosity Honey has a high viscosity 2.2

Conductivity The ability of a material to allow heat to flow through it. Good heat conductors are usually a good electrical conductor. 2.2

Malleability and Hardness The ability of a solid to be hammered without shattering. Most metals are malleable. Solids that shatter when struck are brittle. Hardness is based on which substance will scratch the other. 2.2

Melting point and boiling point Melting point is the point at which a substance changes from a solid to a liquid. Boiling point point is the point at which a substance changes from Liquid to a gas. 2.2

Density Is a ratio of the mass of a substance to the volume of the substance. Density can be used to test the purity of a substance. 2.2

Using Physical Properties To identify Materials 1. Decide which property to test. 2. Do the test on an unknown sample. 3. Compare the results with known material data. 2.2

Using Physical Properties To Choose Materials Don’t only look at one property Make sure it fits all your needs 2.2

Using Properties to Separate Mixtures Mixtures can be separated by Physical means. What are some ways to separate mixtures? 2.2

Filtration Separating an substance based on particle size. Using a strainer or screen. 2.2

Distillation The process that separates substances based on boiling points. 2.2

Distillation, Magnets & Evaporation

Separation of a Heterogeneous Mixture The iron chips in a mixture of iron and sulfur may be removed by stirring the heterogeneous mixture with a magnet.

Fractional Distillation 2.2

Recognizing Physical Change In a physical change, the substances are not altered chemically, but merely changed to another phase (i.e. gas, liquid, solid) or separated or combined. Uses little energy. Some can be reversed and some can not be reversed.

Chemical Properties Chemical properties are properties of an element or compound in chemical reactions. The fact that sodium reacts with water is a chemical property. Iron will rust when exposed to water and oxygen. Flammability (+ oxygen) Acidic or basic 2.3

Chemical Change In a chemical change, the substances are altered chemically and display different physical and chemical properties after the change. Needs a lot of energy. Is not easily reversible. 2.3

Signs of Chemical Change Release of gas 2.3

Signs of Chemical Change Color change 2.3

Signs of Chemical Change Formation of a precipitate 2.3

Signs of Chemical Change Energy change Exothermic Endothermic 2.3

The difference between physical and chemical change ONLY in a chemical change do you end up with a NEW substance Chemical changes cannot be reversed! Physical changes can be reversed!!! 2.3

Chemical Reactions Synonymous to chemical change. Atoms switch partners. Rust Bromine and Phosphorus A precipitate of cadmium sulfide 2.3

Elemental formula Is composed of 2 parts Chemical symbol representing the element Subscripts to show the number of atoms present O 2 or N 2 or H 2 or S 8 2.3

Chemical formula Is composed of 2 parts Chemical symbols representing the elements Subscripts to show the number of atoms of each element present 2.3