Let’s review what we know already!

1. Let’s review what we know already!

2. atom • An atom is the smallest particle of an element that has the chemical properties of the element • All atoms of a particular element are the same

3. Chemical symbols • Scientists use chemical symbols to represent the elements • They are one or two letter that stand for the name of an element Example: H is for hydrogen Ca is for Calcium O is for oxygen

5. Periodic table • Russian chemist, Mendeleev published the table as a way to organize the elements • Ordered by their weights of their atoms and their properties • The elements in column are similar in property

6. Using the periodic table of elements In order by atom weight Columns are their group (metals, nonmetals, semimetals, and noble gases) Each column has similar properties

7. Atomic number 2 Helium He Element name 4. 003 Atom mass

8. When is a metal not an element? When it is an Alloy! An alloy is a solution of two or more metals with its own properties. Example: Steel (iron, carbon, chromium, nickel) Bronze ( copper, tin and sometimes zinc)

9. Why Alloy? Alloys are useful because their properties are different from those of the metals from which they are made. Some common uses: Hardware, plumbing, dentistry, tableware, artwork, building materials

10. Is an Alloy a mixture or solution? An alloy is both, a mixture and a solution! • Mixture because the elements mixed together can be different amount (kind of like the fruit salad) • Solution because the metal elements are evenly mixed throughout

11. Classifying Matter

12. How can matter be classified? Vocabulary Physical properties Chemical properties Substance Mixture Element Compound Atom Chemical symbol

13. Look around the classroom at different objects? What materials do you think make up these objects?

14. Matter All of the materials you mentioned are made of matter. They are all different kinds of matter. Matter can be identified by its properties, or characteristics.

15. Physical properties • Are characteristics that can be measured or detected by the senses. Examples: Color Size Odor density

16. Chemical properties • Describe how matter changes when it reacts with other matter Example: the fact that paper burns is a chemical property of paper

17. All matter can be divided into two major groups- Substances and Mixtures Elements and Compounds

18. Other important words to know • Substance- is a material that always has the same makeup and properties, wherever it may be found • Mixture- is a combination of two or more substances.

19. Elements • An element is a substance that cannot be broken down by simple means into any other substance • There are 118 elements (90 found in nature, 22 not found in nature) Examples: Aluminum Copper

20. compounds • Is made up of two or more elements that are chemically combined Examples: Water Sugar

21. Compounds- how are they formed? When elements combine to form compounds they are linked with chemical bonds

22. Water molecule Atom of Oxygen and two atoms of Hydrogen boned together

23. Salt molecule Sodium and chloride bonded together Na is a soft metal that reacts explosively with water Chlorine is a poisonous gas

24. When atoms combine to form molecules they loose their property and together with what they bind with create new properties for at molecule This explains why we can eat table salt!

25. Chemical formula Chemical formula is a group of symbols that show the elements in a compound. The numbers tell us how many of that element. Example: water, H2 O Two hydrogen and one oxygen

26. Living vs nonliving things We know that all things are made of matter We also know that all things have atoms and elements, either mixed together or pure * **ALL Living things have Carbon ! **** This is also called organic material!

27. Organic compounds- “living things” Example: Cholesterol which is found in cells of living things. C 27 H 45 OH How many atoms are in this molecule of Cholesterol?

28. Lesson review: Elements and compounds are both substances, they cannot be broken down into other substances. Elements contain only one kind of atom. Compounds are made up of two or more elements that are chemically combined.

29. Review cont… Two hydrogen atoms and one oxygen atom have combined to form a single molecule of a compound of water. Use a periodic table to locate certain elements ( try: Iodine, chlorine, oxygen)

30. Lesson Part 2 Mixtures vs. compounds

31. Mixtures and compounds Both are made up of more than one element But, they are different…

32. Mixtures Elements keep their original properties Example: Iron shavings and sand mixture – iron is magnetic so we could use a magnetic to separate the sand

34. Mixtures cont… Different composition- which means different amounts of each element every time. They may be different depending on location and time. Example: Fruit salad- all recipes(formulas) are different. Some fruit salad had 2 apples, 3 oranges, 1 banana, 12 strawberries. Another one may have 1 apple, 2 oranges, 5 bananas and 2 strawberries. But they are both called fruit salad.

35. Some common mixtures Window glass Most building material- bricks, cement, asphalt Air Human body contains many mixtures- blood, sweat, tears, saliva

36. Separating mixtures Using the physical properties like size, appearance, texture, color, odor, melting point, boiling point, density, solubility, and magnetic attraction Example: Marbles and sand

37. compounds Always have the same composition They are chemically bonded, so the original elements loose their properties and new properties are created Example: Water because it has two hydrogen and one oxygen and that will never be different.( same composition)

38. Review Lesson part 2 Q: Explain why a mixture cannot be represented by a chemical formula? A: A mixture does not have a constant makeup. It cannot be represented by a chemical formula because the proportions of the components can vary.

39. Review cont… Q: What is the difference between a mixture and a substance? A: A substance has a constant makeup and a set of constant properties; a mixture does not.

40. Review cont.. Q: Suppose you has a mixture of iron pellets, pebbles, and small wood pieces of all about the same size. A: Magnet to attract the iron, add water to the other two and the wood will float and the pebbles will sink.

41. Investigation 3What is a solution? Vocabulary: SOLUTION SOLVENT SOLUTE SURFACE TENSION COHESION

42. Remember mixtures? The main non-living parts of our planet are mixtures Air, Rocks, Water

43. Facts about mixing:even mixing vs. uneven mixing Uneven- If we mixed sand, salt and water together we would have an uneven mixture • This means that no matter how hard we tried we could not take two samples of the mixture and it would have an even amount of salt, sand and water in each. • One sample might have more sand and the other more salt … it is impossible to get them even

44. What happens if a mixture is spread evenly? They are called solutions.

45. Solution- A solution has two main parts ( solvent, and solute) Solvent is the material that is present in the greater amount Solute is the material present that is the smaller amount

46. Most common solutions Sugar dissolved in water.

47. Rate of solution- Which would dissolve faster, a cube of sugar or loose sugar grains? Stuff only can dissolve if the liquid touches the surface of the sugar. So the loose sugar would dissolve faster because all of the grains would have the surface touched. The sugar cube would have to dissolve a little at a time as the liquid dissolved the surface bit by bit.

48. What else can effect the rate of solution? • Increased temperature (heat it up) • Causes the particles to move faster and have more energy • Increasing the movement of the particles (stir it up) -causes the particles to mix together quicker because it bounces the particles around

49. Suspension- Sometimes a mixture can mix for just a limited amount of time A suspension is a liquid mixture in which some particles are temporarily suspended in the mixture

50. Suspension example: Salad dressing