Go to section Pretest 1.What instrument would you use to measure temperature? 2.Which of the following is a unit of volume? a.gram b.atmosphere c.meter d.liter 3.What characteristic of matter can you measure using a graduated cylinder? Chapter 2

Go to section Pretest (continued) 4.The sides of a cube are 2 cm by 2 cm. What is the volume of the cube? 5.What additional quantity would you need to calculate the density of the cube described in Question 4? 6.Which of the following is NOT studied in chemistry? a.composition of matter b.reactions of substances c.properties of materials d.motion of large objects Chapter 2

Pretest Answers 1.What instrument would you use to measure temperature? 2.Which of the following is a unit of volume? a.gram b.atmosphere c.meter d.liter 3.What characteristic of matter can you measure using a graduated cylinder? volume Chapter 2 a thermometer Click the mouse button to display the answers.

Chapter 2 Pretest Answers (continued) Click the mouse button to display the answers. 4.The sides of a cube are 2 cm by 2 cm. What is the volume of the cube? 5.What additional quantity would you need to calculate the density of the cube described in Question 4? 6.Which of the following is NOT studied in chemistry? a.composition of matter b.reactions of substances c.properties of materials d.motion of large objects 8 cm 3 the cube’s mass

Go to section Interest Grabber Classifying Items People classify objects for different reasons. Classifying foods into groups, such as grains, vegetables, and fruits helps people plan meals that maintain a healthy diet. Biologists classify organisms into groups that have similar characteristics, which makes the relationships among organisms easier to see. 1.Devise a classification system for the following items: orange, lime, plum, apple, pear, rose, violet, daisy, gold, and silver. 2.Explain what criteria you used to place items into each category of your classification system. Section 2.1

Interest Grabber Answers 1.Devise a classification system for the following items: orange, lime, plum, apple, pear, rose, violet, daisy, gold, and silver. 2.Explain what criteria you used to place items into each category of your classification system. Answers may vary. Sample answer: Fruit—orange, lime, plum, apple, pear; Flower—rose, violet, daisy; and Element— gold, silver. You could also classify the list based on whether or not the item is a color name. Section 2.1

Go to section 2.1 Classifying Matter A.Pure Substances= matter that always has the same composition B.Elements= substance that cannot be broken down into a simpler substance 1.Ex: Carbon, Oxygen 2.Most elements are solids at room temperature 3.Composed of one type of atom a.Atom= smallest particle of an element 4.Symbols: a.Letters used to represent the element b.Ex: N, Au

Go to section 2.1 C.Compounds = substance made of two or more substances that can be broken down into simpler parts. 1.Made of elements or compounds 2.Always formed in fixed proportion Ex. Water is H 2 O, two hydrogen one oxygen Ex. Carbon Dioxide is CO 2

Go to section 2.1 D.Mixtures= properties vary because composition is not fixed 1. Heterogeneous mixtures=parts are noticeably different a. Ex: soil, chex-mix, sand 2. Homogeneous mixtures= substances are evenly distributed, difficult to tell apart a. Ex: juice, pudding

Go to section 2.1 E.Solutions, Suspensions & Colloids: Classified based on the size of the largest particle 1.Solutions= mixture that dissolves in water homogeneously (Ex: sugar in water) 2.Suspensions= heterogeneous mixture that separates into layers (Ex: Mud or muddy water, Flour suspended in water, Paint, Chalk powder suspended in water, Dust particles suspended in air) 3.Colloids= contains intermediate sized particles, does not form layers, particles are suspended (Ex: milk, fog, Paint, ink, detergents)

Go to section Interest Grabber Distinguishing Features Physical characteristics can be used to describe and distinguish a person from other people. An accurate physical description can often be used to identify a person in a crowd. Practice identifying physical characteristics with the animals listed below. Your teacher will supply you with pictures of each animal. lioncheetah ocelotleopard tigerbobcat 1.What characteristics make these animals similar? 2.What characteristics make them different? Section 2.2

Go to section Interest Grabber Lion Leopard Ocelot Cheetah Tiger Bobcat

Interest Grabber Answers 1.What characteristics make these animals similar? Answers will vary. All the animals have four legs, fur, sharp teeth, and a tail. 2.What characteristics make them different? Answers will vary. There are differences in color, size, and shape of face and body. Section 2.2

Go to section 2.2 A.Examples of Physical Properties 1.Physical Properties= any characteristic of a material that can be observed or measured without changing the composition of the substance a. Viscosity= resistance to flowing i.Decreases with heat b.Conductivity= ability to allow heat to flow i.Usually also conducts electricity c.Malleability= ability of a metal to be hammered without shattering

Go to section 2.2 Physical Properties Cont. d. Hardness= likelyhood to be scratched e. Melting points= temperature at which a solid turns to a liquid f. Boiling point= temperature at which a liquid turns to a gas g. Density= ratio of mass to volume

Go to section Melting and Boiling Points of Some Substances Figure 12

Go to section 2.2 B.Using Physical Properties 1.Physical properties are used to identify a substance (crime scenes, experiments, etc.) 2.Properties determine which substances to use for various purposes. C.Using Properties to Separate Mixtures 1.Filtration= process that separates mixtures based on size of particles 2.Distillation= process separating mixtures based on their boiling points

Go to section 2.2 D.Physical Changes= when some of the properties of the material change but the substances in the material stay the same 1.Solids to liquids 2.Liquids to gases 3.Tearing 4.Ironing

Go to section Interest Grabber Safety Symbols It is important to pay attention to warning labels when working with chemicals. Look at the safety symbols at the right. Write a brief statement for each symbol explaining what actions you need to take to avoid a possible danger. Section 2.3

Interest Grabber Answers A.No flames, sparks, or exposed sources of heat should be present during an experiment. B.When working with poisonous or irritating vapors, work in a well-ventilated area. Avoid inhaling a vapor directly. C.Avoid getting corrosive chemicals on skin or clothing, or in the eyes. D.Tie back long hair and loose clothing, and put on safety goggles before using a burner. Section 2.3

Go to section 2.3 A.Chemical Properties=ability to change the composition of matter 1.Flammability=ability to burn in the presence of oxygen 2.Reactivity= how readily a substance combines chemically with another substance B.Recognizing Chemical Changes: 1.Chemical change= occurs when a substance reacts and forms one or more new substances a.Signs: i. Changes color ii. Produces gas iii. Forms a precipitate

Chapter 2 Go Online More on the issue of arsenic-treated wood Self-grading assessment Articles on properties of matter For links on mixtures, go to and enter the Web Code as follows: ccn For links on chemical and physical changes, go to and enter the Web Code as follows: ccn

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