Quick Review Matter is anything that: a) has mass, and b) takes up space Mass = a measure of the amount of ―stuff‖ (or material) the object contains (don’t confuse this with weight, a measure of gravity) Volume = a measure of the space occupied by the object
States of Matter1) Solid- matter that can not flow (definite shape) and has definite volume.2) Liquid- definite volume but takes the shape of its container (flows).3) Gas- a substance without definite volume or shape and can flow. Vapor- a substance that is currently a gas, but normally is a liquid or solid at room temperature. (Which is correct: ―water gas‖, or ―water vapor‖?)4) Plasma- Ionized gas that contains positive ions and electrons
States of Matter Result of a Definite Definite Temperature Will it Compress? Volume? Shape? Increase? SmallSolid YES YES Expansion NO SmallLiquid YES NO Expansion NO LargeGas NO Expansion NO YES
The 6 Phase Changes1. Melting: Solid to Liquid2. Freezing: Liquid to Solid3. Evaporation: Liquid to Gas4. Condensation: Gas to Liquid5. Sublimation: Solid to Gas6. Deposition: Gas to Solid
Describing MatterProperties used to describe matter can beclassified as: 1) Extensive – depends on the amount of matter in the sample - Mass, volume, calories are examples 2) Intensive – depends on the type of matter, not the amount present - Hardness, Boiling Point
PropertiesWords that describe matter (adjectives)Physical Properties- a property that can be observed and measured without changing the material’s composition.Examples- color, hardness, m.p., b.p.
PropertiesChemical Properties- a property that can only be observed by changing the composition of the material.Examples- ability to burn, decompose, ferment, react with, etc.
Physical ChangePhysical change will change the visible appearance, without changing the composition of the material.Can be reversible, or irreversible Boil, melt, cut, bend, split, crack Is boiled water still water? ***ALL 6 PHASE CHANGES ARE PHYSICAL CHANGES!***
Chemical ChangeChemical Change - a change where a new form of matter is made. Rust, burn, decompose, ferment
Signs of a Chemical Change1. Gas production2. Precipitate formation3. Energy production (light, sound)4. Change in Temperature5. Change in color6. Change in chemical or physical property
Chemical vs. Physical ChangeAsk yourself: Is anything new being made?
3 Types of Matter1. Elements2. Compounds3. Mixtures a. Heterogeneous b. Homogeneous (Solutions)
Pure Substances Pure substances can be either Elements Compounds
1. ElementsSimplest kind of matterCannot be broken down any simpler and still have properties of that element!All one kind of atom. Atoms– the smallest particle or unit of an element that has the properties of that element.
2. CompoundsSubstances that can be broken down only by chemical methods When broken down, the pieces have completely different properties than the original compound. Made of two or more atoms, chemically combined (not just a physical blend!)
3. Mixtures Mixtures are a physical blend of at least two substances; have variable composition. Every part keeps it’s own properties. They can be either:
3. Mixtures (cont.) 1) Heterogeneous – the mixture is not uniform in composition Ex. Chocolate chip cookie, gravel, soil.
3. Mixtures (cont.) 2) Homogeneous - same composition throughout; called ―solutions‖ • Kool-aid, air, salt water
More on Homogenous (solutions) Mixed molecule by molecule, thus too small to see the different parts Can occur between any state of matter: gas in gas; liquid in gas; gas in liquid; solid in liquid; solid in solid (alloys), etc. Most common solutions consist of 1 or more substances dissolved (the dissolved ―stuff‖ is called the solute) in a liquid (called the solvent) If the solvent is water—aqueous solution A true solution will never separate or settle out on its own.
Ways of Separating Mixtures Differences in physical properties can be used to separate mixtures.1) Filtration - separates a solid from the liquid in a heterogeneous mixture (by size)2) Distillation – separates a solution by boiling pointsThere are other ways as well: magnets, evporationchromotography
During any chemical reaction, the mass of the products (right side of arrow) is always equal to the mass of the reactants (left side of arrow).All the mass can be accounted for: Burning of wood results in products that appear to have less mass as ashes; where is the rest?
Example ProblemWhen methane gas burns, and reacts andcombines with oxygen to produce carbondioxide and water vapor. If 4 grams ofmethane reacts with 16 grams of oxygen toproduce 11 grams of carbon dioxide, howmuch water vapor is produced?