Chemistry Chapter 2

Instructions for Jigsaw Chapter 2 – 4 Corners Each of the six lab groups sends one person, with their review workbook to one of the four corners Group 1 – Completes Section 2.1 “Matter” Group 2 – Completes Section 2.2 “Mixtures” Group 3 – Completes Section 2.3 “Elements & Compounds” Group 4 – Completes Section 2.4 “Chemical Reactions” If there are five members in a group, the fifth member completes “Interpreting Graphics” After working with members of other lab groups and answering the review module pages, the students return to their original lab groups and share out the answers to their individual section.

The Elements

Chemistry Notes Chapter 2 Matter and Change 2.1 Matter A.Properties of Matter - (anything that has mass and takes up space) 1) mass – the amount of matter an object contains 2) matter that has a uniform and definite composition is called a substance a) all samples of a substance will have identical physical properties. b) a physical property is a quality of a substance that can be observed or measured without changing the substance’s composition - physical properties include color, solubility (ability to dissolve), hardness, odor, density, melting point and boiling point B.States of Matter 1.solid – definite shape, definite volume, expands little with heating, almost incompressible, molecules packed tightly together 2.liquid – indefinite shape, definite volume, some expansion with heat, almost incompressible, liquids can flow and take the shape of the container 3.gas – indefinite shape, indefinite volume, expands greatly with heat, readily compressible, gases flow to take the shape of any container 4.vapor – (not one of the three states of matter) it is a gaseous state of a substance that is normally liquid at room temperature C.Physical Change – alters matter without changing the chemical composition (cut, grind, bend, tear, melt, crush, boil, break, split, freeze)

Chemistry Notes Chapter 2 Matter and Change 2.2Mixtures A. Classifying Mixtures – most samples of matter are mixtures 1.mixture – a physical blend of two or more substances, their composition may vary throughout the mixture 2.heterogeneous mixture – a mixture that varies and is not uniform in composition throughout, i.e. a salad 3.homogeneous mixture - a mixture that is completely uniform throughout a. a homogeneous mixture is also called a solution b. solutions may be: gas – gas (i.e. air), liquid – gas (i.e. moist air) gas - liquid (i.e. soda), liquid – liquid (vinegar), solid – liquid (salt water), solid – solid (steel) c. any part of a system with a uniform composition and properties is called a phase d. heterogeneous mixtures consist of matter in two or more phases B.Separating Mixtures 1. Some mixtures can be separated by simple physical methods 2. distillation is a method of separating mixtures that are not easily separated by hand. In distillation, a liquid is boiled to produce a vapor that is then condensed back into a liquid, solid particles initially dissolved in the liquid separate out when the liquid is boiled because they do not turn into vapor as easily

Chemistry Notes Chapter 2 Matter and Change 2.3 Elements and Compounds A.Distinguishing Elements and Compounds 1. Elements are the simplest forms of matter that can exist under normal laboratory conditions, cannot be separated into simpler substances by chemical means 2. Two or more elements combined chemically form compounds, compounds can only be separated into simpler elements by chemical means a.the properties of compounds (elements joined together) can be very different from any of the elements that make up the compound b.it is sometimes difficult to differentiate between a homogeneous mixture and a compound B.Symbols and Formulas 1. Each element known to exist is represented by a universal chemical symbol a.symbols are usually 1 -2 letters b.the first letter of a symbol is capitalized, the second letter lower case c.the symbols are often based on the element’s name in Latin or Greek 2. Chemical formulas indicate how many of each element are present in a compound a.elements making up a particular compound are always found in the same proportions b.the formula for a specific compound is always the same

Chemistry Notes Chapter 2 Matter and Change 2.4 Chemical Reaction A.Changing Reactants to Products 1. Elements have the capability to combine chemically with other elements to form compounds through chemical reactions 2. In any chemical reaction, reactants react to form products 3. The ability of an element to undergo a chemical reaction is its chemical property 4. a chemical change always results in a change of chemical composition of the substances 5. words such as burn, rot, rust, explode, ferment usually signify a chemical change 6. Chemical reactions are written with reactants on the left side of an arrow (normally) and products are written on the right side of an arrow, the arrow itself means that something has “changed into” 7. Chemical reactions are often accompanied by: a.energy release or absorbtion b.change in color or odor c.production of a gas from a solid or liquid d.irreversibility – you cannot change the product back into the reactant easily B.Conservation of Mass 1. During any chemical reaction, the quantity of matter is unchanged 2. The mass of the products always equals the mass of the reactants, this is called the law of conservation of mass 4. the law states that in any chemical or physical reaction, mass is neither created nor destroyed, it is conserved