Unit 1. Matter and Change Do Now: What are the parts of the scientific method and explain each part? Objective Identify the common steps of scientific methods Identify types of variables Describe the difference between a theory and a scientific law Identify the characteristics of a substance Distinguish between physical and chemical properties Differentiate among the physical states of matter Objectives Continued Define physical and chemical changes and list common changes Apply the law of conservation of mass to chemical reactions Activities: Q&A Solve problems Exit Ticket Scientific Method (p12) Systematic approach used in scientific study Method for scientists to verify the work of others Steps of Scientific Method Observation Hypothesis Experiments Conclusion Theory/ Scientific Law Observation Act of gathering information Qualitative Data- color, shape, odor other physical characteristics Quantitative Data – some type of measurement. It is numerical. Ex. Height, weight, how fast, how slow etc. Hypothesis Tentative explanation for what has been observed. Experiment Set of controlled observations used to test the hypothesis Must carefully plan and set up one or more laboratory experiments in order to change and test one variable at a time. Independent Variable – Variable that you plan to change. ( what you can control) Dependent Variable – variable that changes based on the independent variable Conclusion Judgment obtained based on the information Ch. 3 - Matter I. Kinetic Molecular Theory States of Matter A. Kinetic Molecular Theory KMT Particles The of matter are always in motion. kinetic energy (speed) of these particles increases as temperature increases. Three States of Matter Solids very low KE - particles vibrate but can’t move around fixed shape fixed volume Three States of Matter Liquids low KE - particles can move around but are still close together variable fixed shape volume Three States of Matter Gases high KE - particles can separate and move throughout container variable shape variable volume Vapor- Gaseous state of a substance that is a solid or liquid at room temperature. Matter and its Properties It’s Classified! Physical vs. Chemical Physical Property can be observed without changing the identity of the substance Extensive Chemical or intensive properties Property describes the ability of a substance to undergo changes in identity Extensive vs. Intensive Extensive Property depends on the amount of matter present ex,.- Intensive Property depends on the identity of substance, not the amount Ex.- Extensive vs. Intensive Extensive Property depends on the amount of matter present ex,.- Volume, mass, Energy Intensive Property depends on the identity of substance, not the amount Ex.- melting point, boiling point, conduct electricity or heat WHAT ABOUT DENSITY?? A. Extensive vs. Intensive Examples: boiling point volume mass density conductivity A. Extensive vs. Intensive Examples: boiling point…… intensive Volume …. extensive Mass ….. extensive Density ….. intensive Conductivity ….. intensive Physical vs. Chemical Physical Change changes the form of a substance without changing its identity properties remain the same Chemical Change changes the identity of a substance products have different properties Signs of a Chemical change in color or odor formation of a gas formation of a precipitate (solid) change in light or heat B. Physical vs. Chemical Examples: melting point physical flammable chemical density physical magnetic physical tarnishes chemical in air B. Physical vs. Chemical Examples: melting point physical flammable chemical density physical magnetic physical tarnishes chemical in air B. Physical vs. Chemical Examples: rusting iron dissolving in water burning a log melting ice grinding spices B. Physical vs. Chemical Examples: rusting iron dissolving in water chemical physical burning a log chemical melting ice physical grinding spices physical Law of Conservation of Mass Mass is neither created nor destroyed during a chemical reaction. It is conserved In a chemical reaction, the mass of the reactants must equal the mass of the products Law of Conservation of Mass Pg. 78 #7 A student carefully placed 15.6 g of sodium in a reactor supplied with an exess quantity of chlorine gas. When the reaction was complete, the student obtained 39.7f of sodium chloride. Calculate how many grams of chlorine gas reacted. How many grams of sodium reacted? Law of Conservation of Mass Pg. 78 #7 A student carefully placed 15.6 g of sodium in a reactor supplied with an exess quantity of chlorine gas. When the reaction was complete, the student obtained 39.7f of sodium chloride. Calculate how many grams of chlorine gas reacted. How many grams of sodium reacted? 24.1 g of chlorine gas, 15.6 of sodium Law of Conservation of Mass Pg. 78 #7 A student carefully placed 15.6 g of sodium in a reactor supplied with an exess quantity of chlorine gas. When the reaction was complete, the student obtained 39.7f of sodium chloride. Calculate how many grams of chlorine gas reacted. How many grams of sodium reacted? 24.1 g of chlorine gas, 15.6 of sodium HW Pg 79 (10 and 13 only) Do Now: DO NOW: What is a solution? Describe the difference between a heterogeneous and homogenous mixture Calculate % by Mass Objective: SWBAT: Contrast Mixtures and substances Classify mixtures as homogeneous or heterogeneous List and describe several techniques used to separate mixtures. Distinguish between elements and compounds Activities Q&A Solve problems Exit Ticket Objective: Activities: A. Matter Flowchart MATTER yes Can it be physically separated? MIXTURE yes Is the composition uniform? Homogeneous Mixture (solution) PURE SUBSTANCE no Heterogeneous Mixture Colloids no yes Can it be chemically decomposed? Compound Suspensions no Element A. Matter Flowchart Examples: graphite pepper sugar paint soda (sucrose) A. Matter Flowchart Examples: graphite element pepper hetero. mixture sugar compound (sucrose) paint hetero. mixture soda solution Pure Substances Element composed of identical atoms EX: copper wire, aluminum foil Pure Substances Compound composed of 2 or more elements in a fixed ratio properties differ from those of individual elements EX: table salt (NaCl) Pure Substances Law A given compound always contains the same, fixed ratio of elements. Law of Definite Composition of Multiple Proportions Elements can combine in different ratios to form different compounds. Pure Substances For example… Two different compounds, each has a definite composition. Pure Substances (constant composition) Elements Listed on the Periodic Table Cannot be broken down into unique components Na, Cl, Al, O2, S8 Compounds Made of elements that are chemically joined Can be broken down NaCl, H2O, AlCl3, H2SO4 Diatomic Elements Hydrogen Nitrogen Oxygen Fluorine Chlorine Bromine Iodine There are 7 diatomic elements These atoms are never alone, if they are the pair up with the same atom C. Mixtures Variable combination of 2 or more pure substances. Heterogeneous Homogeneous C. Mixtures Solution homogeneous very small particles no Tyndall effect Tyndall Effect C. Mixtures Colloid heterogeneous medium-sized particles Tyndall effect particles don’t settle EX: milk C. Mixtures Suspension heterogeneous large particles Tyndall effect particles settle EX: fresh-squeezed lemonade Mixtures (variable composition) Homogeneous Solutions – evenly distributed Heterogeneous not evenly distributed Tea – Homogeneous Mixture Air – Homogeneous Mixture Alloys – Homogeneous Mixtures Cereal – Heterogeneous Mixture Sand – Heterogeneous Mixture C. Mixtures Examples: mayonnaise muddy water fog saltwater Italian salad dressing C. Mixtures Examples: mayonnaise colloid muddy suspension water fog colloid saltwater solution Italian suspension salad dressing % by Mass = Percent by Mass AKA % composition Example P 88 # 19 A 78.0 g sample of an unknown compounds contains 12.4 g of hydrogen. What is the present by mass of hydrogen in the compound? Example P 88 # 19 A 78.0 g sample of an unknown compounds contains 12.4 g of hydrogen. What is the present by mass of hydrogen in the compound? % mass = (12.4/78.0) * 100 = 15.9% Extra problems: Pg 88 (# 22-23) HW Pg 90 (28) Pg 94 (32, 37, 38, 40, 42, 43,44,50,52, 57,58,60, 62, 64, 76, 92) Do Now: Look at your periodic table. What important information can you get from the PTOE? Objectives Find patterns in the Periodic Table Classify elements as metals, non-metals or metalloids Distinguish between metals, non-metals or metalloids Activities PPT Group work The Periodic Table A. Mendeleev Dmitri Mendeleev (1869, Russian) Organized elements by increasing atomic mass. Elements with similar properties were grouped together. There were some discrepancies. C. Johannesson A. Mendeleev Dmitri Mendeleev (1869, Russian) Predicted properties of undiscovered elements. C. Johannesson B. Moseley Henry Moseley (1913, British) Organized elements by increasing atomic number. Resolved discrepancies in Mendeleev’s arrangement. C. Johannesson How PTOE is organized Metals Nonmetals Metalloids C. Johannesson B. Blocks Main Group Elements Transition Metals Inner Transition Metals C. Johannesson Periods and Families Periods: horizontal rows on the periodic table physical and chemical properties change somewhat regularly across a row. Elements closer to each other in the same period tend to be similar than those that are farther apart. Families: groups vertical rows of elements, aka Each group contains similar chemical properties Types of Elements METALS: Shiny Conductors of heat and electricity Most metals are malleable (can be pounded into thin sheets; a sugar cube sized chunk of gold can be pounded into a thin sheet which will cover a football field), Most metals are ductile (can be drawn out into a thin wire). All are solids at room temp (except Mercury, which is a liquid) Metals tend to have low ionization energies, and typically lose electrons (i.e. are oxidized) when they undergo chemical reactions Alkali metals are always 1+ (lose the electron in s subshell) Alkaline earth metals are always 2+ (lose both electrons in s subshell) Compounds of metals with non-metals tend to be ionic in nature. Types of Elements NON- METALS: Vary greatly in appearance Non-lustrous Poor conductors of heat and electricity The melting points of non-metals are generally lower than metals Seven non-metals exist under standard conditions as diatomic molecules: H2(g) N2(g) O2(g) F2(g) Cl2(g) Br2(l) I2(l) (volatile liquid evaporates readily) Nonmetals, when reacting with metals, tend to gain electrons (typically attaining noble gas electron configuration) and become anions: Nonmetal + Metal -> Salt Compounds composed entirely of nonmetals are molecular substances (not ionic) Types of Elements Metalloids: Elements may share properties of metals and non-metals. Exit Ticket: Classify the following as either a METAL, NON-METAL or METALLOID: a. Au b. Si c. Br d. An element that is brittle and conducts electricity e. An element that is malleable f. An element that has tendency to become an anion Review of Unit List topics we have covered. Study for test!