Understanding Elements, Compounds, and Mixtures

1. Warm Up • 1. A small amount of a strong smelling sulfur compound is dissolved in natural gas to give gas a detectable odor. Which substance is the solvent? • 2. True or False: A mixture has a set ratio of components. • 3. Carbon dioxide is a gas at room temperature, but the element carbon is a solid. How can these two substances be so different?

2. Elements • A substance that cannot be separated or broken down into simpler substances. • Pure substance – only has one type of particle (atoms). • Elements are found on the periodic table • 111 elements known

3. Elements • Every atom in a piece of gold is the same, no matter where it is found. • Every atom of iron is the same • spoon, steel rod, meteorite

4. I can describe the characteristics of elements, and give examples.

5. Properties of Elements • Characteristic properties – do not depend on the amt. of the element present. • Boiling point, melting pt., density, reactivity with acid, color, hardness, flammability • Can be used to identify elements

6. Properties of Elements • Identified by their physical and chemical properties • Categorized by similar properties • Metals, nonmetals, or metalloids

7. Classifying Elements • Metals • Shiny, conduct heat and electricity, malleable, ductile • All are solid except mercury • Examples: copper (Cu), tin (Sn), lead (Pb), iron (Fe), gold (Au), mercury (Hg)

8. Classifying Elements 2. Nonmetals • Opposite of metals • dull, poor conductors heat and electricity, brittle, not malleable, not ductile • Can be solid, liquid, or gas • Examples: sulfur (S), iodine (I), neon (Ne), chlorine (Cl), oxygen (O), hydrogen (H)

9. Classifying elements 3. Metalloids • Properties of both metals and nonmetals • Semi-conductors • Some shiny, some dull, somewhat malleable and ductile, some conduct heat and electricity • Solids • Examples: boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te)

10. I can distinguish between metals, nonmetals, and metalloids.

11. Substances • Matter that has the same composition and properties throughout is called a substance. • When different elements combine, other substances are formed.

12. Substances • Contains only one particle • Can exist in 3 states of matter • Can be elements or compounds Picture from http://www.ilpi.com/msds/ref/gifs/statesofmatter.gif

13. Compounds • A compound is a substance whose smallest unit is made up of atoms of more than one element bonded together. • Compounds often have properties that are different from the elements that make them up. • Examples: Water, salt, sugar

14. Compounds Have Formulas • H20 is the chemical formula for water, and H2O2 is the formula for hydrogen peroxide. • The formula tells you which elements make up a compound as well as how many atoms of each element are present.

15. How to read a formula H20 This is a subscript. It tells us how many atoms of that element exist in one unit of that compound. Hydrogen is made of 2 H atoms and 1 O atom. No subscript is used when only one atom of an element is present.

16. Let’s try it… • Using your white board tell how many atoms there are in each element. • Sulfuric Acid H2SO4 • 2 Hydrogen • 1 Sulfur • 4 Oxygen • Hydrogen Peroxide H2O2 • 2 Hydrogen • 2 Oxygen

17. And some more formulas… • Carbon Dioxide CO2 • 1 Carbon • 2 Oxygen • Carbon Monoxide CO • 1 Carbon • 1 Oxygen • Calcium Carbonate (Found in shells, eggshells, antacid) CaCO3 • 1 Calcium • 1 Carbon • 3 Oxygen

18. Compound Review •  A pure compound has the same elements and the same amount of elements all of the time • Elements are chemically combined • Compound properties are different from the properties of the elements • They cannot be separated physically • Physical properties such as boiling point or melting point of pure substances are do not change

19. Mixtures • A mixture is a combination of two or more substances where there is no chemical combination or reaction.

20. A mixture is a combination of two or more substances where there is no chemical combination or reaction.

21. Mixtures combine physically in no specific proportions. They just mix.

22. Solids, liquids and gases can be combined to create a mixture.

23. Mixture Types • MIXTURES MAY BE HOMOGENEOUS OR HETEROGENEOUS

24. Homogeneous Mixtures • Homogeneous Mixtures: • The prefix: "homo"- indicates the same • Have the same uniform appearance and composition throughout

25. Solutions • SOLUTIONS are homogeneous mixtures

26. What is a solution? • A solution is a mixture of two or more substances. • At least two substances must be mixed in order to have a solution

27. A solution has two parts • The substance in the larger amount is called the SOLVENT - it does the dissolving • IN most common instances water is the solvent • The substance in the smallest amount and the one that DISSOLVES is called the SOLUTE

28. Examples of solutions • Salt water • Clean Air • Vinegar

29. Heterogeneous Mixtures: • The prefix: "hetero"- indicates difference • A heterogeneous mixture consists of visibly different substances or phases • Two or more parts can be seen

30. Examples: • Pizza • Sandwich • Chex Mix

31. Suspensions • A SUSPENSION is a heterogeneous mixture of large particles • These particles are visible and will settle out on standing • Examples of suspensions are: fine sand or silt in water or Italian salad dressing

32. Compounds vs Mixtures Mixtures Compounds Not chemically combined Combine chemically forming molecules Can combine in any proportion Combine in set proportions Separated chemically Separated physically

33. Comparing Elements, Compounds & Mixtures

34. Identify the following with as many terms as apply • Table salt • Salad • Mayonnaise • Italian dressing • Pepsi • Oxygen • Hydrogen • Water Mixture Element Compound Suspension Colloid Solution Homogeneous Heterogeneous