Chapter 2 Matter and Change

Properties of Matter Properties are a way to _________ matter and can be classified as ________________ –Extensive – depends on __________ –Intensive – depends on _______, not _______ Substance – definition Every sample of substance has same intensive properties because _______________

Properties Properties can be used to identify matter Physical properties describe a substance with no interactions with other substances

Physical Properties Physical properties – definition –Examples, Table 2.1 – Are these intensive or extensive properties? –Intensive examples – –Extensive examples – –Remember, all samples of the substance have the same intensive property. Will 2000 liters of water have the same boiling point as 2.0 mL of water? Why?

2.1

–A 22.4 cm long copper wire has an orange- brown color, and will conduct electricity. The wire is ductile and can be made into various shapes (malleable). It has a density of 8.92 grams per cubic centimeter and it will melt at 1085 degrees Celsius. –List any extensive properties. –List any intensive properties.

States of matter – intensive physical properties (why?) –Solid, liquid, gas –Page 41 – describe the differences in shape, volume, and arrangement of particles in a solid, liquid and gas –_______________ of particles determines shape and volume –_____________of particles determines the arrangement

States of Matter –Solids A solid is a form of matter that has a definite shape and volume. Not easily compressed 2.1

States of Matter –Liquid A liquid is a form of matter that has an indefinite shape, flows, yet has a fixed volume. Not easily compressed 2.1

States of Matter –Gases A gas is a form of matter that takes both the shape and volume of its container. Easily compressed 2.1

Physical Changes Physical changes –Some properties of a material change, but the ____________ does not –Same substance is present after the change –Reversible changes – –Irreversible changes –

Physical changes depend on physical properties. What property determines each change? PHYSICAL CHANGE Ice melts Sugar dissolves A car is dented The window shatters PHYSICAL PROPERTY

Page 39, vocabulary Page 42, # 1-8 and elements handbook Page 44, vocabulary

Mixtures Mixture – definition Heterogeneous – composition is _________ Examples: Homogeneous – composition is _________ throughout Examples: Phase – definition

______________ mixtures consist of one phase ______________ mixtures consist of two or more phases

Homogeneous Mixtures –Homogeneous mixtures can be solutions or substances Solution – consist of solutes dissolved in solvents –Composition can vary if amount of solute or solvent varies Solutions can be liquid, gas or solid (examples) Substances - have uniform and definite composition –Either an element or compound Substances are mixtures that are chemically combined. Solutions are mixtures that are a physical blend.

Substance vs Mixture (Solution) How are substances and solutions alike? How are substances and solutions different?

Separating Mixtures Separating mixtures (homogeneous solutions or heterogeneous mixtures) Physical properties are used to separate components in mixtures –Since mixtures are physical blends, physical properties can separate the components –Separate aluminum from iron – conceptual problem 2.1, page 46 – what properties are used?

Filtration – definition – what properties? Distillation – definition – what properties? Chromatography Evaporation

–Filtration The process that separates a solid from the liquid in a heterogeneous mixture is called filtration. A colander is used to separate pasta from the water in which it was cooked. This process is a type of filtration. Could filtration separate sugar from water? Explain. 2.2

–Distillation During a distillation, a liquid is boiled to produce a vapor that is then condensed into a liquid. –Vapor – definition condensed - definition Separate liquids with different boiling points 2.2

Page 47, Section Assessment # 11 – 17 –#15 – use definitions for each term Page 48, vocabulary

Substances Element – definition Compound – definition –Properties of compounds are different from component elements, figure 2.10 Properties of oxygen? Properties of hydrogen? Properties of water?

A change in composition produced a change in properties –How is the composition of water different from the composition of oxygen or hydrogen? Compounds can be broken down into simpler substances by chemical changes but not physical changes Since compounds are chemical combinations

Distinguishing Elements and Compounds Sodium is stored under oil to keep it from reacting with oxygen or water vapor in the air. Sodium vapor produces the light in some street lamps. 2.3

Distinguishing Elements and Compounds Sodium Chloride (commonly known as table salt) is used to season or preserve food. 2.3

Chemical changes Chemical changes – definition –Compounds can be broken down into simpler substance by chemical changes. Elements cannot be broken down into anything simpler. –Physical changes will not break down compounds into simpler substances

Distinguishing Elements and Compounds –Breaking Down Compounds A chemical change is a change that produces matter with a different composition than the original matter. When table sugar is heated, it goes through a series of chemical changes. 2.3

Distinguishing Elements and Compounds The final products of these chemical changes are solid carbon and water vapor. The following diagram summarizes the process. 2.3

Substances and solutions (both homogeneous mixtures) Review: –Definitions of substance, mixture, solution –Figure 2.11 –How are substances and solutions different? –How are substances and solutions the same? Page 51, Conceptual Problem 2.2

Practice Problem # 18 & 19, page 51

Classification of Matter Matter that is composed of components that are physically combined in variable composition can be –Heterogeneous mixtures –Homogeneous mixtures – solutions Matter that is composed of components that are chemically combined in definite composition are –Homogeneous substances – elements and compounds

Classifying Matter This flowchart summarizes the process for classifying matter. 2.3

Symbols and Formulas Symbols – definition Formulas – definition Berzelius Table 2.2 – memorize symbols from Latin names Subscripts – represent relative proportions of elements in a compound –Compounds have fixed composition

Symbols and Formulas 2.3

Page 52, Section Assessment # , skip #24 Page 52, Writing Activity Page 53, Vocabulary

Chemical Reactions Review - Chemical changes produce matter with ________________________. A chemical change is also called a chemical reaction Reactants – definition Products - definition

Because compounds are ____________ combined substances, a ____________ change will separate the compound into its component elements Chemical changes also combine elements into compounds

Chemical properties Chemical properties – definition Involve how or if a substance will react with another substance –Examples – Observed only when a substance undergoes a chemical change

Chemical changes depend on chemical properties CHEMICAL CHANGE Paper burns The car rusts Aluminum foil disintegrates in hydrochloric acid PROPERTY

Page 53, figure 2.13 – distinguish between physical change and chemical change

Chemical Changes vs Physical Change A magnet separates iron from sulfur. This is an example of a physical change. 2.4

Chemical Changes vs Physical Change A mixture of iron and sulfur is heated. The iron and sulfur react and form iron sulfide. This is an example of a chemical change. 2.4

Chemical Change vs Physical Change –During a chemical change, the composition of matter always changes. –Recall that during a physical change, the composition of matter never changes. –Describe a physical change you could make to paper. Describe a chemical change you could make to paper. 2.4

Recognizing Chemical Changes 4 signs of a chemical change –Energy transfer, formation of precipitate, formation of gas, color change Precipitate - definition –Signs are not absolute

Chemical Changes Page 54, figure 2-14 A – bubbles of gas form B – color changes C – milk separates into curds and whey 2.4

Page 55, figure 2-15 How do you know that a chemical reaction took place when the 2 liquids in A were mixed? 2.4

Examples of chemical changes For each example what is one sign that a chemical change has occurred? –Metal reacts with acid –Calcium reacts with water –Bags of Reactions lab –Iron rusts

Conservation of Mass When wood burns, where does the matter go? In any chemical or physical change, the mass of the products must equal the mass of the reactants State the Law of Conservation of Mass –More easily observed in a closed container Mass is defined as __________________

Page 55, Section Assessment - # Chapter 2 Assessment –Page , # 35 – 72, skip 38, 53, 65 –Page 60, #77 and 81 ******Standardized Test Prep - #

Chapter 2 Outline Physical properties –Intensive & extensive –Include states of matter Physical changes –Reversible & irreversible –Used to separate mixtures Distillation, filtration, chromatography

Mixtures –Homogeneous & heterogeneous Physical combinations –Substance – compound & element Chemically combined Symbols and formulas Chemical changes, chemical reactions Chemical properties Chemical change vs. Physical change Law of conservation of Mass