Chapter 2 in hard cover text

2.1 PROPERTIES OF MATTER Describing Matter Extensive Properties – a property that depends on the amount of matter in a sample. MASS and VOLUME Intensive Properties – a property that depends on the type of matter in a sample, not the amount of matter HARDNESS, COLOR, and OTHER QUALITIES

Identifying Substance Pure Substance – matter that has uniform and definite composition Every sample of a pure substance has identical intensive properties because every sample has the same composition Physical Property – quality or condition of a substance that can be observed or measured w/o changing the composition temperature, hardness, color, conductivity, and malleability

States of Matter Solid – has definite shape and volume. The shape of a solid does not depend on the shape of the container. Particles are tightly packed in a rigid orderly arrangement. Liquid – has definite volume and indefinite shape. Particles are on close contact with one another and the container, yet are not in a rigid or orderly arrangement. Particles are free to flow from one location to another and take the shape of the container.

States of Matter (con’t) Gas – has indefinite shape and indefinite volume. Meaning that it takes the shape and volume of the container. Particles are much farther apart then the particles in a liquid. Because the space between particles gases are easily compacted into smaller volumes.

Physical Changes During a physical change some of the properties of a substance can change but the composition of the material does not Reversible – boil, freeze, melt, and condense Irreversible – break, split, grind, cut, crush

2.2 MIXTURES Classifying Mixtures Mixture – physical blend of two or more components Based on their components mixtures can be heterogeneous or homogeneous Heterogeneous Mixture – mixture in which the components are not uniform throughout Homogeneous Mixture – mixture in which the composition is uniform throughout Ex. A solution Phase – used to describe any part of a substance that is uniform throughout. Hetero – 2 or more phases Homo – only 1 phase

Separating Mixtures Differences in physical properties can be used to separate mixtures Filtration – the process of separating solid from a liquid by using a filter of some sort Example: pasta and water Distillation – a liquid is boiled to create vapor and cooled in a separate chamber and collected back to a liquid

2.3 ELEMENTS AND COMPOUNDS Distinguishing Elements & Compounds Elements – simplest form of matter that has unique set of properties Compounds – made of 2 or more elements and can be broken down into simpler substances by chemical means, but elements cannot

Breaking Down Compounds Chemical Change – a change that produces matter with a different chemical composition then the original matter Examples: cooking, baking, chemical reaction Properties of Compounds – in general the properties of compounds are very different then their component elements

Distinguishing Substances and Mixtures If the composition of a material is fixed (can’t change), the material is a pure substance. If the composition of a material may vary, the material is a mixture.

Symbols and Formulas Chemists use chemical symbols to represent elements and chemical formulas to represent compounds Elements have a one or two letter chemical symbol. The first letter is always capitalized. When a second letter is present, it is always lowercase. Formulas have the symbols together w /o spaces and each element keeps its capital letter. Subscripts denote multiple parts of an element Example: H 2 O, C 6 H 12 O 6

2.4 Chemical Reactions Chemical Changes Chemical Property – the ability of a substance to undergo a specific chemical change During a Chemical Change, the composition of the matter always changes. Chemical Reaction – another name for a chemical change. One or more substances change into one or more new substances during the process. Reactant – the substance ate the start of the chemical reaction Product – the substance produced or the result of a chemical reaction.

Recognizing Chemical Changes Possible clues to chemical change include a transfer of energy, a change of color, production of a gas, or the formation of a precipitate. Precipitate – solid that forms and settles out a liquid mixture

Conservation of Mass During a chemical reaction, the mass of the products is always equal to the mass of the reactants.