CHEMISTRY World of Zumdahl Zumdahl DeCoste

Chapter 2 Matter Copyright© by Houghton Mifflin Company. All rights reserved.

Overview Learn about the composition of matter Learn the difference between elements and compounds Distinguish between physical and chemical properties and changes Distinguish between mixtures and pure substances Learn 2 methods of separating mixtures Copyright© by Houghton Mifflin Company. All rights reserved. 3

Did you ever wonder?... How do plants grow & why are they green? Why is the sun hot? Why does a hot dog get hot in a microwave? Why does wood burn and rocks do not? How does soap work? Why does pop fizz? What’s happening when iron rusts? Why doesn’t aluminum foil rust? How does a hair permanent work? Copyright© by Houghton Mifflin Company. All rights reserved. 4

The Particulate Nature of Matter Matter: the “stuff” the universe is composed of – Has mass and occupies space – Comes in many forms: the stars, your chair, brain tissue Composed of tiny particles called atoms – Scanning tunneling microscope produces images of atoms – Can’t see with naked eye, similar to looking at beach from far away; can only see sand particles when you get close Copyright© by Houghton Mifflin Company. All rights reserved. 5

Elements and Compounds Atoms: all matter is composed of these tiny particles – Over 100 different atoms – Similar to words, all made from 26 different letters – All matter made from about 100 different atoms Copyright© by Houghton Mifflin Company. All rights reserved. 6

7 Compounds: substances made by bonding atoms together in specific ways -Contain 2 or more different types of atoms -Same throughout Compound: always contains atoms of different elements (water = H2O) Molecule: made up of atoms that are “stuck” together

Atom Combinations Copyright© by Houghton Mifflin Company. All rights reserved. 8

Elements Elements: substances that contain only one type of atom Some atoms can combine with like atoms to form molecules: H 2 & O 2 Carbon bonds forming large groups Copyright© by Houghton Mifflin Company. All rights reserved. 9

Top Ten Copyright© by Houghton Mifflin Company. All rights reserved. 10

Figure 2.5: The three forms of the element carbon: Diamond. Copyright© by Houghton Mifflin Company. All rights reserved. 11

Figure 2.5: The three forms of the element carbon: Graphite. Copyright© by Houghton Mifflin Company. All rights reserved. 12

Figure 2.5: The three forms of the element carbon: Buckminsterfullerene. Copyright© by Houghton Mifflin Company. All rights reserved. 13

The States of Matter Copyright© by Houghton Mifflin Company. All rights reserved. 14

Figure 2.7: The three states of water: Solid. Solids: Rigid; have a fixed shape and volume Copyright© by Houghton Mifflin Company. All rights reserved. 15

Figure 2.7: The three states of water: Liquid Liquid: has a definite volume but takes the shape of its container Copyright© by Houghton Mifflin Company. All rights reserved. 16

Figure 2.7: The three states of water: Gas. Gas: has no fixed volume or shape; uniformly fills any container Copyright© by Houghton Mifflin Company. All rights reserved. 17

Physical and Chemical Properties and Changes Physical Properties: Odor, color, volume, state, density, melting point, and boiling point Copyright© by Houghton Mifflin Company. All rights reserved. 18

Copyright© by Houghton Mifflin Company. All rights reserved. 19 Chemical properties: refer to a substances ability to form new substances Examples: wood burning, rusting of steel, digestion of food, growth of grass Given substance changes to a fundamentally different substance or substances

Chemical vs. Physical change in water Physical changes solid → liquid → gas Change of state: H 2 O molecules still present Chemical change = electrolysis – water changed into different substances (water decomposes to hydrogen & oxygen)

Figure 2.8: Electrolysis, the decomposition of water by an electric current, is a chemical process. Copyright© by Houghton Mifflin Company. All rights reserved. 21

Physical & Chemical Changes Physical change involves a change in one or more physical properties, but no change in fundamental components of substance. Most common are changes in state. Chemical change involves a change in the fundamental components of the substance. Chemical changes are called reactions.

Mixtures and Pure Substances Mixture: something that has variable composition – Examples: soda, coffee, tap water, air Composition of mixtures varies, but composition of compounds is always the same Composition depends on how much of each component is used when mixture is formed Can be separated into pure substances: elements and/or compounds

Figure 2.9: The composition of air. Copyright© by Houghton Mifflin Company. All rights reserved. 24

Chart examining each substance of air. Copyright© by Houghton Mifflin Company. All rights reserved. 25

Mixtures: Alloys Alloys: mixtures of metals – Many gold alloys: mixture of gold, copper, and silver – They are not compounds! (like water) – Composition varies

Figure 2.10: Twenty-four-karat gold is an element Eighteen-karat gold is an alloy. Fourteen-karat gold is an alloy. Copyright© by Houghton Mifflin Company. All rights reserved. 27

Homogeneous and Heterogeneous Homogeneous mixture is the same throughout, & also called a solution – Examples: salt water, air, brass (mixture of copper and zinc) Heterogeneous mixture contains regions that have different properties from other regions – Examples: sand/water mixture, rocky road ice cream, chocolate chip cookie dough

Copyright© by Houghton Mifflin Company. All rights reserved. 29 A solution is a homozygous mixture solute: dissolved in solvent solvent: the dissolving agent Saturated: can hold no more solute Concentrated: large amount of solute Dilute: small amount of solute

Copyright© by Houghton Mifflin Company. All rights reserved. 30 Suspensions: cloudy mixtures. They mix together but do not dissolve. ex. Starch water, peanut butter Emulsion: suspension of 2 liquids ex. Mayo., and lotion

Figure 2.11: Representation of H 2 O molecules. Copyright© by Houghton Mifflin Company. All rights reserved. 31

Distillation: Separation Process Boil water (or other liquid) Vaporizes (turns into gas = steam) Condense (cool steam in tube) – turns back to liquid Minerals are left behind Pure water collected Physical change

Figure 2.14: The solution is boiled and steam is driven off. Copyright© by Houghton Mifflin Company. All rights reserved. 33

Figure 2.14: Salt remains after all water is boiled off. Copyright© by Houghton Mifflin Company. All rights reserved. 34

Figure 2.15: No chemical change occurs when salt water is distilled. Copyright© by Houghton Mifflin Company. All rights reserved. 35

Filtration: Separation Process Pour mixture onto a mesh, such as filter paper Liquid passes through, solid is left behind on filter paper

Figure 2.16: Filtration separates a liquid from a solid. Copyright© by Houghton Mifflin Company. All rights reserved. 37

Figure 2.17: Separation of a sand-saltwater mixture. Copyright© by Houghton Mifflin Company. All rights reserved. 38

Pure Substances Pure substances are either elements or compounds Always have same chemical and physical properties

Figure 2.18: The organization of matter. Copyright© by Houghton Mifflin Company. All rights reserved. 40

Setup to boil water. Copyright© by Houghton Mifflin Company. All rights reserved. 41