Matter: Properties and Changes Chapter 3.1: Properties of Matter
Substances Review: Matter is anything that has mass and takes up space. Matter with uniform and unchanging composition is pure substance. ie~ Table salt (NaCl) What about H2O? Pure water = yes; seawater / tap water = no.
Sates of Matter States of Matter All matter that exists can be classified into one of three forms: Each can be distinguished by the way it fills a container. Exception to rule: plasma (fourth state of matter) Found in lightning bolts and stars.
States of Matter Solid Definite shape and volume. Particles tightly packed. Expands slightly when heated.
States of Matter Liquid Flows and has constant volume. Particles not held in place and packed less closely. Able to move past one another. Takes shape of container. Expands when heated.
States of Matter Gas Flows to conform to shape of container & fills entire volume. Expands to fill containers. Particles are very far apart Easily compressible.
States of Matter Gases vs Vapor Do not mean the same thing! Gas is a substance that is naturally in the gaseous state at room temperature. Vapor refers to gaseous state of substance that is solid or liquid at room temperature Helium? Neon? Steam?
Physical Properties of Matter Characteristic that can be observed or measured without changing the composition. Also describe pure substances. Uniform and unchanging compositions = consistent and unchanging properties. Examples include: Density, color, odor, hardness, melting point, boiling point.
Physical Properties of Matter Two Types Extensive Dependent on the amount of substance present. Examples include: Length, mass, & volume.
Physical Properties of Matter Two Types Intensive Independent on the amount of substance present. Examples include: Density- always the same regardless of how much substance is present. Substances can be identified by intensive properties. ie~ scent
Chemical Properties of Matter The ability of a substance to combine with or change into one or more other substances. Composition of substance changes. Results from contact with other substances or addition of energy (thermal or electric). Example: Iron = Forms rust when in contact with oxygen in air Copper =
Chemical Properties of Matter Each substance has its own unique set of physical and chemical properties. Copper: Can be shaped into different forms (physical) or turns green when in contact with air (chemical)
Matter: Properties and Changes Chapter 3.2: Changes in Matter
Changes in Matter Physical Change Changes in appearance but not composition. Examples include: 1) Cutting sheet of paper 2) Breaking glass object 3) Crumpling piece of aluminum foil
Changes in Matter Phase Change Transition of matter from one state to another. Depends on temperature and pressure of surroundings. As temperature and pressure change, substances change from one phase to another. Example is the water cycle: 1) Ice (solid) is heated to become liquid water. 2) Add more heat, liquid water boils and is converted to steam (gas). What type of changes are these? Physical (Different appearance but same composition)
Changes in Matter Phase Change Melting and Boiling Points The temperature and pressure at which a substance undergoes a phase change. Intensive physical properties that can be used to identify unknown substances.
Changes in Matter Chemical Change One or more substances changing into new substances. aka~ chemical reaction New substances formed have different compositions and properties.
Changes in Matter Chemical Reaction Starting substances = reactants. New substances formed = products.
Changes in Matter Chemical Reaction Evidence includes a change in properties. ie~ spoiled food: What are some changes in properties? Look, taste, digestability...
Changes in Matter Law of Conservation of Mass Mass is neither created nor destroyed during a chemical reaction. It is conserved. mass of reactants = mass of products. Although chemical changes occur, total mass remains constant.
Changes in Matter Law of Conservation of Mass Mass is neither created nor destroyed during a chemical reaction. A 10.0 g sample of magnesium reacts with oxygen to form 16.6 g of Magnesium oxide. How many grams of oxygen reacted?
Matter: Properties and Changes Chapter 3.3: Mixtures of Matter
Changes in Matter Most everyday matter occurs as mixtures. Combination of two or more pure substances. Each pure substance retains its individual chemical properties. Composition of mixtures is variable.
Changes in Matter Types of Mixtures Heterogeneous Mixture that does not blend smoothly. Composition is not uniform. Substances remain distinct. Examples include: salad dressing, orange juice, etc.
Changes in Matter Types of Mixtures Homogeneous Has constant composition throughout. Always has single phase. Referred to as solutions.
Changes in Matter Solutions Most familiar with liquid forms. Examples include: tea, lemonade, etc Solution systems can be solid, liquid, or gas. Solid-solid solutions of metals are known as alloys. Examples include: steel, bronze, 14-karat gold.
Changes in Matter Solutions
Separating Mixtures Important to be able to separate mixtures to understand nature of matter. Use physical processes to separate mixtures based on physical properties. ie~ magnet to separate metal from sand.
Separating Mixtures Filtration Separates heterogeneous mixtures composed of solids and liquids. Uses a porous barrier.
Separating Mixtures Distillation Used to separate most homogeneous mixtures. Based on differences in boiling points. 1) Mixture is heated until lower boiling point boils to vapor. 2) Vapor is condensed into liquid and collected.
Separating Mixtures Crystallization Results in the formation of pure solid particles of a substance. Solid particles come from solution containing dissolved substance. Solids are highly pure Example: rock candy
Separating Mixtures Sublimation Solid changes to vapor without going through liquid phase. Used to separate one solid that sublimates form one that does not.
Separating Mixtures Chromatography Separates components of a liquid mixture (mobile phase) based on ability of each to travel across another material (stationary phase). Components flow through stationary phase at different speeds.
Matter: Properties and Changes Chapter 3.4: Elements and Compounds
Elements & Compounds Matter can take many different forms. All matter can be broken down into basic building blocks called elements. Element is a pure substance that cannot be separated into simpler substances by physical or chemical means. 92 natural elements Several others that have been developed
Elements & Compounds Elements have unique chemical names & symbols. Names consist of 1/2/3 letters. First ALWAYS capitalized; rest are lowercase. 92 natural elements not evenly distributed. H2: 75 % of mass of universe. O2, H2, C: 90% of human body Under normal conditions, elements can be found in each type of phase. (ie~ Cu, Hg, He)
Elements & Compounds Elements organized into a periodic table. Based on similarities and masses Rows = periods Columns = groups / families Elements in same group have similar chemical and physical properties.
Elements & Compounds Compounds made up of two or more different elements that are chemically combined. Most matter in the universe exists as compounds. Chemical formulas of compounds Composed of chemical symbols and subscripts. 10 million known; ~ 100,000 developed each year. Subscripts indicate number of elements in each compound. ie~ H2O, NaCl
Elements & Compounds Compounds can be broken down into simpler elements by chemical means. Compounds generally more stable than individual elements. Requires energy (ie~ heat or electricity). Electrolysis is breakdown of H 2O. *** What do you notice about the amount of H2 compared to the amount of O2?
Properties of Compounds Properties of a compound are different from those of the individual elements. ie~ H 2O How is H 2O different than H2 & O2?
Properties of Compounds Properties of a compound are different from those of the individual elements.
Properties of Compounds Organization of Matter Pure substances & mixtures. Separation???
Law of Definite Proportions Elements in compounds combine in definite proportions by mass. Law of Definite Proportions = Compound is composed of same elements in the same proportion by mass. Mass of the compound = sum of masses of elements that make up the compound.
Law of Definite Proportions Amounts of elements in a compound can be expressed as percent by mass. Ratio of the mass of each element to the total mass of the compound. A 1.0 g sample of hydrogen reacts with 19.0 g of fluorine. What is the % of hydrogen in the compound?
Law of Definite Proportions Amounts of elements in a compound can be expressed as percent by mass. Ratio of the mass of each element to the total mass of the compound. Percent by mass the same regardless of amount of sucrose; each has the same mass proportion
Law of Multiple Proportions Use when comparing different compounds composed of the same elements. Law of Multiple Proportions = Different compounds are formed by a combination of the same elements, different masses of one element combine with the same relative mass of the other element in a ratio of small whole numbers.
Law of Multiple Proportions mass ratio of Compound I mass ratio of Compound II = 1.793 g Cu / g Cl 0.8964 g Cu / g Cl = 2.000 Mass ratio of copper to chlorine in Compound 1 is exactly two times the mass ratio of copper to chlorine in Compound II. 2:1