Properties of Matter Chemistry I Matter Occupies space (volume) Has a mass Is represented by three phases: Solid (s) Liquid (l) Gas (g) General Properties of Matter SOLID LIQUID GAS COMPRESSIBILITY NONE NONE HIGH RIGIDITY HIGH NONE NONE FLUIDITY NONE HIGH HIGH SHAPE DEFINITE NOT NOT DEFINITE DEFINITE DEFINITE DEFINITE NOT DEFINITE VOLUME Physical Properties of Matter Characteristics that can be observed or measured without changing the sample’s composition. Extensive Properties: depend upon the amount of the substance present. Intensive Properties: independent of the amount of substance present. Examples: mass, length, volume Examples: density, color, state, melting point, boiling point, texture, conductivity, malleability, ductility Intensive properties can help identify what an unknown substance is, extensive cannot. Chemical Properties of Matter A chemical property relates to a substances ability to undergo a chemical change that will change it to a NEW substance with different properties. Examples are: alkalinity, acidity, corrosiveness, ability to react with water, flammibility Changes in Matter - Physical Are changes in a substance that does not involve a change in the identity of the substance. Examples: cutting, grinding, any phase change. Changes in Matter - Chemical A chemical change is a change in a chemical property. This is also called a chemical reaction. A new substance is formed as a result of a chemical change. Examples: explode, rust, oxidize, corrode, tarnish, ferment, burn, rot No matter is lost or gained during a chemical change. This is called the Law of Conservation of Mass. How do you observe a chemical change? A chemical change is evidenced by: A change in color and/or The production of bubbles, indicating a gas has formed, and/or A change in temperature and/or Formation of a precipitate (a solid which is produced when 2 liquid substances are combined). A chemical change is represented by a chemical equation A chemical equation has two basic parts, the reactants and the products. Reactants: starting substances Products: new substances formed Reactant + Reactant → Product + Product H2 + O2 → H2O2 Practice Physical/Chemical Changes Classify the following as physical or chemical changes: 1. 2. 3. 4. 5. 6. 7. 8. Bending a piece of wire Burning coal Cooking a steak Dissolving sugar in water Cutting grass Growing grass Souring of milk Stretching a rubber band Law of Conservation of Mass Mass is neither created or destroyed during a chemical reaction, it is conserved. Massreactants = Massproducts Mercury (II) oxide yields mercury + oxygen 216 g = 200 g + 16 g Classifying Matter Matter Pure Substances Elements Compounds Mixtures Homogeneous Heterogeneous Pure substances One material only Has a consistent composition throughout Elements Simplest form of matter Made up of atoms with the same number of protons Cannot be broken into any simpler form of matter Combine in simple whole ratios to form compounds Representative particle is the atom Elements Elements Diatomic Polyatomic Monatomic Monatomic Elements Exist in nature as single atoms Most of the elements on the periodic table are monatomic Diatomic Elements Are found in nature as two atoms of the same element that are chemically joined These elements, in their pure uncombined form, are diatomic: Hydrogen (H2) Oxygen (O2) Fluorine (F2) Bromine (Br2) Iodine (I2) Nitrogen (N2) Chlorine (Cl2) Remember the first seven common diatomic elements as: HOFBrINCl Polyatomic Elements Exist in nature as 3 or more atoms of the same element found bonded together. Phosphorus, Carbon, and Sulfur are polyatomic elements Atoms combine to make compounds Diatomic hydrogen Diatomic oxygen Two molecules of hydrogen + one molecule of oxygen form two molecules of water Compounds One material made of two or more elements Compounds can be separated by chemical means (chemical reaction is required) Mixtures Mixtures are made up of two or more substances that are not chemically combined Separation of mixtures is by physical means Filtering Crystallization Distillation/Evaporation if the two substances have different boiling points Homogenous Mixtures Homogeneous Mixtures Solutions All homogeneous mixtures are solutions Solutions Solutions exist as a mixture of two or more substances that are evenly distributed throughout the entire mixture. Solutions are made of two components: Solute – the substance that dissolves Solvent – the dissolving medium. The solvent is present in greater quantity. Solutions continued Solutions Solid solutions are known as alloys Examples of alloys are brass (copper & zinc), bronze (copper & tin), and pewter (copper, tin, & antimony) Liquid solutions can be solid, liquid, or gas phase Examples: salt water, sugar water, water & alcohol Gas solutions Example: air Solutions do not settle or scatter light since the solute particle is extremely small Heterogenous Mixtures Heterogeneous mixtures Colloids Suspensions Heterogeneous mixtures The two or more substances in this mixtures are not evenly distributed throughout the substance. Colloids – have intermediate particle size Can not be filtered Scatter light (known as the Tyndall effect) Do not settle Colloids Examples: fog, milk, blood, gelatin, mayonnaise Tyndall effect The solute particles reflect the light as it passes through making it visible. Suspensions Have a large solute particle Scatter light Can be separated by filtration Solute particles settle if left undisturbed Examples: Italian salad dressing, muddy water Separating Mixtures Filtration: using a porous barrier to separate a solid from a liquid. Separating Mixtures Distillation: separation technique that is based on differences in boiling points of the substances involved. Separating Mixtures Crystallization: separation technique that results in the formation of pure solid particles of a substance from a solution. Separating Mixtures Chromatography: technique that separates the components of a mixture. Periodic Table The Periodic Table organizes the known elements in increasing Atomic Number. This arrangement creates trends and groups that can be used to predict properties of elements. Periods go across the table, while Groups go down the table. Groups are also called families and include: Alkali metals, Alkaline earth metals, Halogens, Noble gases, and Transition metals. Metal, Nonmetals, Metalloids Periodic Table Groups