1. Elements, Compounds, & Mixtures

2. Objectives Describe pure substances Describe the characteristics of elements, and give examples Explain how elements can be identified Classify elements according to their properties Section 1: Elements

3. 3.1 Elements Element- A pure substance that cannot be separated into simpler substances by chemical or physical means. Pure Substance- A substance in which there is only one type of particles

4. Properties of Elements Each element has its own characteristic properties. These include boiling/melting point, density, reactivity, flammability, etc. An element may share one or two properties with another element, but it will not share all its properties with another element. There will be specific properties for each element.

5. Classifying Elements You can use properties to identify elements. Think about how many types of dogs there are. How do you tell one breed from another? Categories of Elements Metals Nonmetals Metalloids

6. Classifying Elements Metal- an element that is shiny and conducts heat and electricity well Properties Malleable – ability to be hammered into sheets Ductile – ability to be drawn into wires

7. Classifying Elements Nonmetal – an element that conducts heat and electric poorly Properties 1. dull 2. brittle – not malleable Metalloid- an element that has properties of metals and nonmetals Properties 1.some are shiny 2. some are dull 3. somewhat malleable and ductile 4. some are good conductors of heat and electricity 5. some are poor conductors of heat and electricity

8. Classifying Elements

9. AppearanceConductivityPhysicallyExample Metal Shiny Good malleable., ductile Lead, Copper Nonmetal Dull Poor Brittle Sulfur, oxygen Metalloid Some Shiny/ some dull Some good/ some poor Somewhat malleable and ductile Silicon, boron

10. Section Review Please answer the objectives on your summary sheet 1.Describe pure substances 2.Describe the characteristics of elements, and give examples 3.Explain how elements can be identified 4.Classify elements according to their properties Section 1: Elements

11. 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 Section 2: Compounds

12. 3.2 Compounds Compound- a substance made up of atoms of two or more different elements joined by chemical bonds Examples: H 2 O (water), NaCl (table salt) A particle of a compound is called a molecule Elements do not randomly combine. They join into a specific ratios according to their masses.

13. Properties Compounds versus Elements A compound will have different ______________ than the elements that make it up Section 2: Compounds properties

14. Compounds Sodium Soft Silvery, white metal Reacts violently with Chlorine Gas Poisonous Greenish-yellow

15. But when chemically combined… You get…….. NaCl = Table salt!

16. Breaking Down Compounds Some compounds can be broken down into their elements or simpler compounds by chemical means. Sometimes energy in the form of heat is needed to do this.

17. Section Review Please answer the objectives on your summary sheet 1.Explain how elements make up compounds 2.Describe the properties of compounds 3.Explain how a compound can be broken down into its elements 4.Give examples of common compounds Section 2: Compounds

18. Objectives Describe three properties of mixtures Describe methods of separating the parts of a mixture Analyze a solution in terms of its solute and solvent Describe factors that affect solubility for solids, liquids, and gases Explain how concentration affects a solution Describe the particles in a solution, suspension, and colloid Explain the difference between colloids, solutions, and suspensions Section 3: Mixtures

19. 3.3 Mixtures Mixture- A combination of two or more substances that are not chemically combined. An example would be a salad (or salsa as in the picture). The cheese, sauce, and dough are still the same items after you make the pizza.

20. Properties of Mixtures Sometimes you cannot see all the components like in salt water This is called a homogeneous mixture. It includes salt and water. Since mixtures are not chemically combined, you can separate the different substances by physical methods. Components in a mixture do not need to be in a specific ratio. Sometimes you can just pick ingredients out of a mixture (pizza) This is called a heterogeneous mixture

21. Separating Mixtures  Other ways to separate mixtures include:  evaporation – separates a mixture based on boiling points Ex: salt in water Filtration - a process to separate materials based on their size. Ex: coffee filters and a screen to find artifacts at a historical site.  distillation – separates a mixture based on density. Ex: crude oil – gasoline & propane  centrifuge – separates based on particle size Ex: blood

22. Compounds vs. mixtures MixturesCompounds Made of elements, compounds or both Made of elements No change in original properties of components Change in original properties of components Separated by physical meansSeparated by chemical means Formed by using any ratio of components Formed using a set ratio of components

23. Mixture vs. compound vs. element

24. Solutions, Suspensions, & Colloids

25. Solutions Solution- A mixture that appears to be a single substance. Particles are small & cannot be filtered Solutions have the same composition throughout. Example: Salt Water Solute- Substance that is dissolved. (Salt) Solvent- The substance in which the solute is dissolved. (water)

26. Solutions Continued The term soluble means able to dissolve. Insoluble means unable to dissolve. Solutions can be solids, liquids, or gases. Solubility- Measure of the amount of solute dissolved in a solvent. This is expressed as g/mL To increase solubility: heat stir crush – smaller particles

27. How does temperature affect solubility? For liquid solvents A higher temperature makes a gas _______ soluble A higher temperature makes a solid _______ soluble USUALLY A higher temperature makes a liquid more soluble Section 3: Mixtures less more

28. To get solids to dissolve faster… Section 3: Mixtures Mix, stir, or shake Heat Crush

29. Colloids Colloid A type of mixture in which the particles are dispersed throughout but are not heavy enough to settle out Particle size is larger than that of a solution but small enough they will still pass through a filter. Examples of colloids: milk, fog

30. Colloids  Colloids scatter light. (fog) You can actually see the beam of light in the colloid.

31. Suspensions Suspensions- A mixture in which the particles of a material are dispersed throughout a liquid or gas but are large enough that they settle out. Particles are large enough to settle out. Suspensions can be separated by passing through a filter. Examples: Italian salad dressing, muddy water

32. Elements, Compounds, Mixtures ElementsCompoundsMixtures How many parts make it up? 1 2 or more 2 or more elements or compounds Pure: more than one substance? pure Not pure Chemically or physically combined? N/A Chemicallyphysically Chemical change to make them? N/A Yesno Fixed ratio? N/AYesno How separated: chemically/ physically? N/AChemicallyphysically

33. Solution, suspension, colliod ElementsCompoundsMixtures How many parts make it up? 1 2 or more 2 or more elements or compounds Pure: more than one substance? pure Not pure Chemically or physically combined? N/A Chemicallyphysically Chemical change to make them? N/A Yesno Fixed ratio? N/AYesno How separated: chemically/ physically? N/AChemicallyphysically

34. Section Review Please answer the objectives on your summary sheet 1.Describe three properties of mixtures 2.Describe methods of separating the parts of a mixture 3.Analyze a solution in terms of its solute and solvent 4.Describe factors that affect solubility for solids, liquids, and gases 5.Explain how concentration affects a solution 6.Describe the particles in a solution, suspension, and colloid 7.Explain the difference between colloids, solutions, and suspensions Section 3: Mixtures