Class TAKS Review Objective 4

1. Class TAKS Review Objective 4 Matter and Change

2. Matter • Anything that has mass and takes up space. • Energy is NOT matter

3. Matter is divided into 3 types: • Elements • Compounds • Mixtures

4. Pure Substances Elements are the simplest pure substances Mixtures are not pure substances and we will deal with them in a few minutes. The 3 types can be further separated in two categories: • Compounds which are formed when two or more elements share electrons or become ions that attract other elements.

5. Atoms are. . . • The smallest part of a single element. • The basis of all matter. • Made of mostly empty space. • Have a positive core or nucleus. • Have electrons in orbit in clouds.

6. 4 Basic Types of Elements • Metals: found on the left and center of the Table of Elements • Non-metals: found on the right side of the Table of Elements • Metalloids: found along the stair-step line • Synthetic: made in the laboratory and not yet found in nature – many of the Actinide and Lanthanide series and very large # elements.

7. Where are the metal elements? Left of the Stair-step line!

8. Properties of Elements - Metals • Metals are: • Conductors • Lustrous • Electron donors • Malleable • Ductile

9. Where are the nonmetals? To the Right of the stair step line, and Hydrogen!

10. Properties of Nonmetals • Nonmetals are brittle, insulators, electron acceptors • Usually form negative ions (except H) • Many are gases at room temperature • Found to the right of the stair-step line

11. 23 According to the periodic table, which element most readily accepts electrons? • A Fluorine • B Nitrogen • This is a nonmetal, so it accepts electrons but it will also share them as in NO31-. • C Arsenic • This is a metalloid, so it only sometimes accepts electrons. • D Aluminum • This is a metal so it donates electrons. Fluorine only needs 1 electron to complete its shell of 8, so it will accept it from any other element very very very easily. This periodic property increases as you move up and left in the table, except for the Noble Gases.

12. The BOHR Model of an Atom • This is the first model to have a nucleus with protons and neutrons. • The electrons are in various energy levels and circle the nucleus. • Model most people draw today.

13. Use the Table provided! What do the numbers mean? This is the atomic number. It is the number of protons in a single atom of this element. By the way, its also # of electrons. 11 Na The symbol for this element. This is the atomic mass, it is the number of protons + neutrons, or the mass of the nucleus of an atom. 22.990 sodium This is the name of the element.

14. Diatomic Elements – Nonmetals that come as molecules • 7 Elements are di- (2) atomic (atoms) • The easy way to remember them is by the name • Br I N Cl H O F

15. 3 Which of the following groups contains members with similar chemical reactivity? A Li, Be, C B Be, Mg, Sr C Sc, Y, Zr D C, N, O

16. Lets look at the Table provided. • To have similar chemical properties of any kind, they must be in the same Group or Family. • Groups are columns, so the answer would be • B

17. Chemical Reactivity • Metals increase in reactivity left and down. • Nonmetals become more reactive up and to the right. • Most reactive metal is? • Most reactive nonmetal is? Fr F

18. Names of Compounds – Ionic • Ionic compounds consist of cations (positive ions) and anions (negative ions). • A Roman numeral in parentheses, preceded by the name of the element, is used for elements that can form more than one positive ion. This is usually seen with metals. • Fe2+ Iron (II) Cu+ Copper (I)Fe3+ Iron (III) Cu2+ Copper (II)

19. Ionic compounds – naming cont. • The -ide ending is added to the name of a single element when it becomes an ion of that element. Oxide, Nitride, Sulfide etc. • Some polyatomic anions have a names ending in -ite for the lower # of oxygens and –ate for more oxygens. • NO2nitrite NO3nitrate

20. Covalent Compounds – Names are the Formulas • These are nonmetal to nonmetal compounds. • The name tells you the formula. Carbon dioxide 1 C and 2 O CO2

21. Bases end in the hydroxide anionOH- They are named with the metal and hydroxide. NaOH is sodium hydroxide Acids that are two elements are named Hydro-nonmetal –ic Acid such as HCl hydrochloric acid Group -ate becomes –ic and -ite becomes –ous. H2SO3 sulfurous acid H2SO4 sulfuric acid Special Names of Compounds Acids and Bases

22. 15 An advertisement claims that patients can be cured of the common cold in 48 hours by vitamin C tablets with secret mineral supplements. In a scientific experiment to test these claims, which data can be considered irrelevant? A The amount of vitamin C in each tablet B The severity of the patients’ cold symptoms C The chemical formula for vitamin C D The amount of time before symptoms improve

23. What doesn’t matter to the test? A The amount of vitamin C in each tablet This should be a controlled variable! B The severity of the patients’ cold symptoms This would be very hard to control, but a large experimental group should allow for differences C The chemical formula for vitamin C Compound formulas NEVER change so this is our answer it is irrelevant!!! D The amount of time before symptoms improve This is what we are testing, it is most relevant.

24. Changes in Matter – Physical or Chemical? • Physical changes are changes in the state of matter. They do not change the substance. (Melting, boiling, condensing, freezing, cutting) • Chemical changes are reactions that result in new products with new properties.

25. Physical changes do not change the substance. The state of the matter may change, but it keeps its own properties. Cutting a piece of wood does not change the wood, it is simply smaller. Chemical changes are also called chemical reactions. When a different substance is produced than what was present at the start, a chemical change has occurred. Changes in Matter – Physical, Chemical or Nuclear?

26. Fusion occurs when the nucleus of one atom is joined by the nucleus of another. This is the reaction that occurs on the sun and stars. It produces extreme energy release. Fission occurs when the nucleus of an atom ejects particles and energy when hit by a subatomic particle such as a neutron. This also causes a release of extreme energy and is the basis of atomic energy plants and bombs. Nuclear Changes: Fission and Fusion

27. Density = Mass / Volume THIS IS FROM THE FORMULA PAGE 25 A block of maple wood with a volume of 405 cubic centimeters and a density of 0.67 g/cm3 is sawed in half. The density of the two smaller blocks is now — A one-fourth the original density B one-half the original density C two times the original density D the same as the original density If the block is cut in half, you cut the mass in half AND you cut the volume in half, so Mass/2 or Volume/2 Mass x 2 (which is really 1) so . . . . Volume 2

28. 20 A sample of an element has a volume of 78.0 mL and a density of 1.85 g/mL. What is the mass in grams of the sample? Record and bubble in your answer to the nearest tenth on the answer document. Use the formula page, D = M/V 1.85 g/mL = Multiply both sides by 78.0 mL and you get: 144.3 g Grid it in!

29. Law of Conservation of Matter • Matter can not be created or destroyed. • The total mass of the substances before they are mixed is equal to the total mass as a mixture.

30. Since matter can not be created or destroyed, chemical reactions must be balanced in terms of mass. The amount of mass you start with must be equal to the mass of the products. Reactants  Products 100g total = 100g total Chemical Reactions

31. 39 According to the law of conservation of mass, how much zinc was present in the zinc carbonate? A 40 g B 88 g C 104 g D 256 g Since matter can not be created or destroyed in chemical reactions, the mass on both sides of the arrow must be equal. So 64g + 192g = 256g and 152 g + Zinc = 256g There must be 104g of Zinc. Answer C.

32. Chemical Equations • Whole numbers written in front of formulas are called coefficients. For example, 4 C6H12O6 indicates that there are 4 molecules of glucose sugar. • To determine how many total atoms of each element are present, multiply the coefficients by the subscripts for each element. • 4 C6H12O6 would contain 24 atoms of carbon (4 x 6), 48 atoms of hydrogen (4 x 12), and 24 atoms of oxygen (4 x 6).

33. To balance equations: • The number of atoms of each type of element on the reactant side (left of the arrow) must be equal those on the product side (right side of the arrow). 2 H2 + O2 2 H2O • There are 4 hydrogen atoms on the left (2 H2) and 4 hydrogen atoms on the right (2 H2O) • There are 2 atoms of oxygen (O2) on the left and 2 atoms of oxygen on the right (2 H2O). When a subscript is missing, it is understood to be 1.

34. K + H2O  KOH + H2 2 2 2 H OH 19 What is the coefficient for H2O when the above equation is balanced? • A 1 • B 2 • C 3 • D 4 To balance this equation, make water HOH, then you will see that you need 2 H and get 2 OH groups. That means the KOH gets a coefficient of 2, the K gets a coefficient of 2 and The water must also get a coefficient of 2.

35. Balance the equation below, the boxes should get the coefficients. 2 2 Which element does not have the same number of atoms on both sides? Oxygen. It has 2 on the reactant side and 3 on the product side. If we put a coefficient of 2 in front of PbO, we will now have 4 O and 2 Pb on the right. By placing a coefficient of 2 in front of the reactant, we have 2 Pb and 2 x 2 O. That means it is balanced! Answer? C

36. Pure Substances Elements are the simplest pure substances Mixtures are not pure substances. Each part of a mixture keeps its own properties, and can be separated out by a physical change. The 3 types can be further separated in two categories: • Compounds which are formed when two or more elements share electrons or become ions that attract other elements.

37. Decide if the substance is Element, Compound , or Mixture? 1. Water 1. Compound 2. Compound 2. Table Salt 3. Element 3. Oxygen 4. Mixture 4. Dirt 5. Mixture/Solution 5. Air Click Mouse button to see answers!

38. Let’s try a few more! 6. Copper 6. Element 7. Solution/Mixture 7. Soda 8. Solution/Mixture 8. Steel 9. Mixture 9. Rain 10. Mixture 10. Ice-cream Click Mouse button to see answers!

39. P r o p e r t i e s o f M i x t u r e s : • E a c h s u b s t a n c e r e t a i n s i t s o w n p r o p e r t i e s . • S u b s t a n c e s c a n b e p r e s e n t i n a n y a m o u n t . • S u b s t a n c e s c a n b e s e p a r a t e d b y s i m p l e p h y s i c a l m e a n s.

40. There are two types of mixtures: • Heterogeneous- mixture is not the same from place to place. • Chocolate chip cookie, gravel, soil. • Homogeneous- same composition throughout. • Kool-aid, air, brass.

41. Separating Mixtures – Physical Changes • Separation of mixtures could be: • Magnetic removal (if there is Fe, Ni, Co) • Filtration (if there are large particles) • Hand sorting particles • Decanting (pouring off the less dense liquid)

42. Another technique for separating mixtures: Evaporation: changing from a liquid to vapor state– leaves behind the other component.

43. Distillation: • Process used to remove vapor from liquid by heating • Great for separating two or more liquids which have different boiling points.

44. So, what is a suspension or colloid? • Suspensions have larger particles, often visible in size. • The particles can be filtered out. • It scatters light – No Tyndall Effect. • If left undisturbed, the particles will settle to the bottom. • Colloids have small particles that are not visible by just looking. An example would be coffee. • However, they show the Tyndall Effect (see the laser light line). • They can not be separated by filtering.

45. Solutions: 2 parts • S o l v e n t - t h e m o s t a b u n d a n t s u b s t a n c e i n t h e s o l u t i o n . • S o l u t e - t h e l e a s t a b u n d a n t s u b s t a n c e i n t h e s o l u t i o n . • Homogeneous: You can not see any particles of either part!

46. The three methods to increase the rate of solution for a solidare? • Heat it! • Crush it! • Stir it!

47. 17 All of these can affect the rate at which a solid dissolves in water except — A decreasing air pressure B stirring the water C increasing the temperature of the water D using larger crystals of the solid

48. Heat it! C Crush it! D slows it Stir it! B So this eliminates choices B, C & D Which will NOT change it? A Answer choices were: A decreasing air pressure B stirring the water C increasing the temperature of the water D using larger crystals of the solid The three methods to increase the rate of solution for a solid are?

49. Solubility Factors – What will dissolve? Solubility Rules • 1. All sodium, potassium, and ammonium salts are soluble. • 2. All silver, lead, and mercury salts are insoluble. • 3. All carbonates, sulfides, and hydroxides are insoluble. • 4. All nitrates and sulfates are soluble except calcium sulfate and barium sulfate.

50. F Decreasing the water temperature G Stopping the stirring H Lowering the air pressure J Crushing the crystal What are the 3 ways to increase the rate at which a solid dissolves? Heat it! Crush it! Stir it! ANSWER? J 10 A 0.2 g crystal of gypsum dissolves very slowly in 100 mL of water while the water is stirred. Which of these would cause the gypsum to dissolve faster?