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Chapter 4 Preview Section 1 Elements Section 2 Compounds
Elements, Compounds, and Mixtures Preview Section 1 Elements Section 2 Compounds Section 3 Mixtures Concept Mapping
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Chapter 4 Section 1 Elements Bellringer Refer to Figure 4 in your book for help answering the following questions: What do gold, iron, and aluminum have in common? What do oxygen, neon, and sulfur have in common? How is silicon different from aluminum or oxygen?
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Chapter 4 Objectives Describe pure substances.
Section 1 Elements Objectives Describe pure substances. Describe the characteristics of elements, and give examples. Explain how elements can be identified. Classify elements according to their properties. Copyright © by Holt, Rinehart and Winston. All rights reserved.
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Elements, the Simplest Substances
Chapter 4 Section 1 Elements Elements, the Simplest Substances An element is a pure substance that cannot be separated into simpler substances by physical or chemical means. Only One Type of Particle A substance in which there is only one type of particle is a pure substance. Elements are made of particles called atoms.
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Properties of Elements
Chapter 4 Section 1 Elements Properties of Elements Each element can be identified by its unique set of properties. An element may share a property with another element, but other properties can help you tell the elements apart. Identifying Elements by Their Properties Elements can be identified by using their physical properties and their chemical properties.
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Classifying Elements by Their Properties
Chapter 4 Section 1 Elements Classifying Elements by Their Properties Categories of Elements Three major categories are: Metals are shiny, and they conduct heat energy and electric current. Nonmetals conduct heat and electricity poorly. Metalloids have properties of both metals and nonmetals.
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Classifying Elements by Their Properties, continued
Chapter 4 Section 1 Elements Classifying Elements by Their Properties, continued Categories Are Similar By knowing the category to which an unfamiliar element belongs, you can predict some of its properties. The next slide show examples and properties of metals, nonmetals, and metalloids.
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Chapter 4 Section 1 Elements
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Chapter 4 Section 2 Compounds Bellringer The word compound refers to something that consists of two or more parts. How might you make a compound using elements? What are some compounds that you know? Write your answer in your science journal.
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Chapter 4 Objectives Explain how elements make up compounds.
Section 2 Compounds Objectives Explain how elements make up compounds. Describe the properties of compounds. Explain how a compound can be broken down into its elements. Give examples of common compounds.
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Compounds: Made of Elements
Chapter 4 Section 2 Compounds Compounds: Made of Elements A compound is a pure substance composed of two or more elements that are chemically combined. Elements combine by reacting with one another. A particle of a compound is a called a molecule. Molecules of compounds are formed when atoms of two or more elements join together.
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Compounds: Made of Elements
Chapter 4 Section 2 Compounds Compounds: Made of Elements The Ratio of Elements in a Compound Elements join in a specific ratio according to their masses to form a compound. For example, every sample of water has a 1:8 mass ratio of hydrogen and oxygen.
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Properties of Compounds
Chapter 4 Section 2 Compounds Properties of Compounds Each compound can be identified by its physical and chemical properties. Properties: Compounds Versus Elements A compound has properties that differ from those of the elements that form it.
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Breaking Down Compounds
Chapter 4 Section 2 Compounds Breaking Down Compounds Compounds can be broken down into their elements or into simpler compounds by chemical changes. Methods of Breaking Down Compounds Sometimes, energy is needed for a chemical change to happen. Two ways to add energy are to apply heat and to apply an electric current.
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Compounds in Your World
Chapter 4 Section 2 Compounds Compounds in Your World Compounds in Nature Some compounds found in nature are proteins, carbon dioxide, and carbohydrates. Compounds in Industry Some compounds must be broken down for use in industry. Other compounds, are made in industry for use as medicines, food preservatives, and synthetic fabrics.
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Chapter 4 Section 3 Mixtures Bellringer When you add sugar to coffee, tea, iced tea, or lemonade, the sugar disappears. What do you think happens to the sugar? Write your answer in your science journal.
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Chapter 4 Objectives Describe three properties of mixtures.
Section 3 Mixtures Objectives Describe three properties of mixtures. Describe four methods of separating the parts of a mixture. Analyze a solution in terms of its solute and solvent.
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Chapter 4 Objectives, continued
Section 3 Mixtures Objectives, continued Explain how concentration affects a solution. Describe the particles in a suspension. Explain how a colloid differs from a solution and a suspension.
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Properties of Mixtures
Chapter 4 Section 3 Mixtures Properties of Mixtures A mixture is a combination of two or more substances that are not chemically combined. No Chemical Changes in a Mixture No chemical changes happen when a mixture is made. So, each substance has the same chemical makeup it had before the mixture was formed.
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Properties of Mixtures, continued
Chapter 4 Section 3 Mixtures Properties of Mixtures, continued Separating Mixtures Through Physical Methods Mixtures can be separated by using physical changes. Physical changes do not change the identities of the substances. The next slide shows some common ways to separate mixtures by using physical changes.
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Chapter 4 Section 3 Mixtures
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Properties of Mixtures, continued
Chapter 4 Section 3 Mixtures Properties of Mixtures, continued The Ratio of Components in a Mixture The components of a mixture do not need to be mixed in a definite ratio. For example, granite is a mixture of three minerals. Different ratios of the minerals give granite different colors, but the mixture is always called granite.
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Chapter 4 Section 3 Mixtures Solutions A solution is a mixture that appears to be a single substance. The process in which particles of substances separate and spread evenly throughout a mixture is known as dissolving. In a solution, the solute is the substance that is dissolved. The solvent is the substance in which the solute is dissolved.
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Chapter 4 Solutions, continued
Section 3 Mixtures Solutions, continued Examples of Solutions Liquid solutions include soft drinks, gasoline, and tap water. Solutions may also be gases, such as air. Solutions may also be solids, such as steel. Alloys are solid solutions of metals or nonmetals dissolved in metals.
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Solutes, Solvents, and Solutions
Chapter 4 Section 3 Mixtures Solutes, Solvents, and Solutions Click below to watch the Visual Concept. Visual Concept
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Chapter 4 Solutions, continued
Section 3 Mixtures Solutions, continued Particles in Solutions The particles in solutions are so small that they never settle out. They also cannot be removed by filtering. The particles in solutions are so small that they don’t even scatter light.
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Concentrations of Solutions
Chapter 4 Section 3 Mixtures Concentrations of Solutions A measure of the amount of solute dissolved in a solvent is concentration. Concentrated or Dilute? Solutions can be described as being concentrated or dilute. But these two terms do not tell you the amount of solute that is dissolved. The next slide shows how to calculate concentration.
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Chapter 4 Section 3 Mixtures
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Concentrations of Solutions, continued
Chapter 4 Section 3 Mixtures Concentrations of Solutions, continued Solubility is the ability of a solute to dissolve in a solvent at a certain temperature. The solubility of most solids in water increases with temperature. The graph on the next slide shows this relationship.
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Chapter 4 Section 3 Mixtures
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Concentrations of Solutions, continued
Chapter 4 Section 3 Mixtures Concentrations of Solutions, continued Dissolving Gases in Liquids Gases become less soluble in liquids as the temperature is raised. Dissolving Solids Faster in Liquids Three ways to make a solute dissolve faster are mixing the solution, heating the solution, and crushing the solute into smaller particles.
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Chapter 4 Section 3 Mixtures Suspensions A suspension is a mixture in which particles of a material are dispersed throughout a liquid or a gas but are large enough that they settle out. The particles in a suspension are large enough to scatter or block light. A suspension can be separated by passing it through a filter.
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Chapter 4 Section 3 Mixtures Colloids A colloid is a mixture in which the particles are dispersed throughout but are not heavy enough to settle out. Particles in a colloid are large enough to scatter light. A colloid cannot be separated by passing it through a filter.
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Chapter 4 Concept Mapping
Elements, Compounds, and Mixtures Concept Mapping Use the terms below to complete the Concept Mapping on the next slide. mixture colloid filter element suspension solution compound
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Chapter 4 Elements, Compounds, and Mixtures
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Chapter 4 Elements, Compounds, and Mixtures
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