Physical Science: The Structure of Matter

1. Physical Science: The Structure of Matter Review Part Two

2. Properties of Matter Matter has physical and chemical properties. Physical Properties Phase (solid, liquid, gas) Boiling point Freezing point Texture Color Chemical Properties Reactivity Iron is a dark, silver metal that has a high melting point. It is a solid at room temperature. Iron reacts with oxygen to make Iron Oxide (rust).

3. Properties of Matter Matter can change physically and chemically. Physical Change Is it boiling, melting, freezing, or is it being misshapen? Chemical Change Has it reacted with other matter to become something new? When grass is cut, it changes shape, but it is still grass. When gasoline burns, it makes heat, CO2, and water.

4. Mass, Volume, and Density Volume is how much space an object takes up. Volume is measured in cm3 or mL. Mass is the measure of how much material an object is made of. Mass is measured in grams or kilograms. Density is the relationship between mass and volume. It is measured by dividing mass by volume. D=m/v The unit of measurement is g/cm3 or g/mL. These cubes have the same volume, but different masses. The more massive cubes are more dense.

5. Phases of Matter add energy add energy Solid Liquid Gas In a solid, the particles are very attracted to each other. The object holds its own shape, and the particles simply vibrate in place. The particles of a liquid have more energy than the particles of a solid. Liquids take the shape of their container, and the molecules slide around each other. The particles of a gas have more energy than in a liquid. The particles have very little attraction for each other. Gases will take the shape of their container, and the molecules fly in every direction.

6. Phase Change Diagram The phase of a pure substance is affected by pressure and temperature. There are specific names for changing phases. LEAST VOLUME GREATEST VOLUME

7. The Behaviors of Gases Pressure Volume Volume Temperature When gases expand (increase volume), they absorb energy (increase temperature). When gases are compressed, the release energy (decrease temperature). Cold air is more dense than warm air. Pressure Volume When the pressure of a gas increase, the volume decreases. If the pressure decreases, then the volume increases.

8. Phase Change of Water

9. Atomic Structure All matter is made of atoms. Atoms have 2 regions: nucleus electron cloud The nucleus is made of protons and neutrons. The electron cloud only contains electrons. Protons: positive, 1 amu Neutrons: neutral, 1 amu Electrons: negative, 0 amu

10. Atomic Structure The different kinds of atoms are called elements. The number of protons determines the identity of the element (atomic number). The number of protons and neutrons determines the mass of the element. The balance of protons and electrons determines the charge of the element. Atomic Number: 6 Atomic Mass: 12 Charge: 0

11. The Periodic Table The Periodic Table is a chart of all of the elements that exist. There are 18 groups and 7 periods (rows). Element in the same group have similar properties.

12. The Periodic Table Elements on the Periodic Table are either Metals, Nonmetals, or Metalloids.

13. The Periodic Table Elements on the Periodic Table are either solids, liquids, or gases.

14. Reading the Periodic Table

15. Electrons are located in a cloud around the nucleus. However, the cloud is actually organized. It has energy levels (rings) and orbits. Each energy level can only hold so many electrons. When an energy level is full, a new energy level is needed. The outer most energy level is called the valence energy level. The Electron Cloud

16. Valence Electrons Valence electrons are the electrons that are located on the outer most energy level. When elements react or bond, it is the valence electrons that interact. This is because when atoms touch, their valence energy levels are in contact. Although an energy level may be able to hold more than 8 electrons, 8 is considered to be “full.” The only exception is for elements that only have the first energy level, which is full at 2 electrons (Hydrogen for example).

17. Reading the Periodic Table The group that an element is in tells the number of valence electrons that it has. 1 18 2 13 14 15 16 17

18. Isotopes Isotopes are atoms that are the same element, but have different masses (# of neutrons). Nitrogen-14 Protons: 7 Neutrons: 7 Nitrogen-15 Protons: 7 Neutrons: 8 Nitrogen-16 Protons: 7 Neutrons: 9

19. Ions Ions are elements that have an unbalance of protons and electrons. If there are more protons, the ion is positive (cation). If there are more electrons, then the ion will be negative (anion). Count the numbers of protons and electrons to find out what the charge is… e e e e N e P P e P N e e N e e e Li+1 N-3 e

20. Reading the Periodic Table The group that an element is in tells what charge it will have. Metals always form a positive charge(+), and nonmetals form negative charges (-). 1 18 2 13 14 15 16 17

21. a b g e- The nucleus of a helium atom Atomic number decreases by 2 amu Atomic mass decreases by 4 amu Least harmful An electron Mass remains the same, but the atomic number increases by 1 amu High energy electromagnetic waves Most harmful P N 4He P N 2

22. Nuclear Radiation: Types Uranium-238 g Thorium-234 a g Carbon-14 Nitrogen-14 b e- P N P N

23. Nuclear Radiation: Fission In fission, an atom splits into two smaller nuclei. The masses don’t quite add up, because some of the mass was converted into energy (E=mc2). 238 138 99 ENERGY!!!

24. Nuclear Radiation: Fusion In fusion, smaller nuclei combine to produce a larger nucleus. Energy is released when this happens. This is how stars (like our sun) produce energy. ENERGY!!! Hydrogen 2 Hydrogen 2 Helium-4

25. Nuclear Radiation: Half Life During radioactive decay, the amount of radioactive material is cut in half over a certain amount of time. This amount of time never changes, and it is called the half-life. Scientists can look at a sample of rock, compare the amount of radioactive material to stable material, and determine how old the rock is. They use this information to determine the ages of dinosaurs, meteors, and the Earth.

26. Nuclear Radiation: Half Life The process of radioactive decay usually takes several steps. Not every isotope will have the same half-life, but the half-life for a certain kind of isotope is always the same. Some half-lives take years, while others may only take seconds.

27. Nuclear Radiation: Uses and Dangers

28. Ionic Compounds Metals will give electrons to nonmetals so that they both end up with a full valence energy level. This results in the metal becoming positive, and the nonmetal becoming negative. Therefore, they stick to each other (bond) like magnets. NON METALS METALS e - +

29. Ionic Compounds

30. Dissolving Ionic Compounds Ionic compounds break apart when they are dissolved in water. This is called dissociation. Sodium Chloride Na Cl Cl- Na+ Cl- Because the positive and negative ions are exposed, this solution will conduct electricity. Na+ Na+ Na+ Cl- Cl- Cl- Na+ Water

31. Ionic Compounds Use the “criss-cross method” to determine the formula for an ionic compound. When ions bond, the result is a balance of charges of the ions. Na+1 + Cl-1 = NaCl Na+1 + O-2 = Na2O Mg+2 + Cl-1 = MgCl2 Ca+2 + P-3 = Ca3P2

32. Naming Ionic Compounds Name the first element, name the second element, and finish the second element with –ide. NaCl: sodium chloride Na2O: sodium oxide MgCl2:magnesium chloride Ca3P2: calcium phosphide

33. Molecular or Covalent Compounds Nonmetals will share electrons so that they all have full valence energy levels. Covalent bonds are stronger than ionic bonds, and the bonded elements are referred to as molecules. In this example, both Hydrogen atoms are sharing their one valence electron with Oxygen. This allows Hydrogen to have 2 total, and Oxygen 8 total. They each have a full valence energy level.

34. Naming Molecular & Covalent Compounds To name molecular/covalent compounds, use the prefix system. Don’t ever use mono for the first element. Also, the last element ends in –ide. CO2: carbon dioxide P2O3: diphosphorus trioxide

35. Dissolving Molecular/Covalent Compounds Molecular/Covalent compounds do not dissociate in water. This is because theirs bonds are too strong. carbohydrate Water

36. Conductivity of Ionic & Molecular Compounds Because ions dissociate in water, a solution of ions will conduct electricity. A solution of molecular compounds will not conduct electricity.

37. Chemical Reactions Under the right conditions, elements and compounds will react with each other in order to reach a greater state of equilibrium. The valence electrons determine the reactivity of a substance. Combustion is the reaction between a hydrocarbon and oxygen.

38. Indicators of Chemical Reactions • How do you know if a chemical reaction is occurring? • A precipitation occurs. • Bubbles • Solid or liquid precipitation sinks. • A change in color. • Energy is absorbed or released as heat or light. • The pH changes (more or less acidic)

39. Understanding Chemical Reactions The ingredients of a chemical reaction are on the left side of the arrow. They are called reactants. The products are on the right side of the reaction, and are simply referred to as “products.” REACTANTS PRODUCTS 2H2 + O2 2H2O

40. Types of Chemical Reactions

41. Balancing Chemical Reactions Chemical reactions must be balanced. This means that the mass of the reactants are equal to the mass of the products. Also, there are the same number of each element in the reactants as there is in the products. The coefficients in front of the compounds/elements determine how many that there are in the reaction. 4 grams of Hydrogen react with 32 grams of oxygen to make 36 grams of water 2H2 + O2 2H2O H H H H H H O O O H H O

42. The Periodic Table: Reactivity In a group, the higher up the element, the more reactive it is. More Reactive Less Reactive

44. Solutions The water in this pitcher of sweet tea is the solvent. The sugar and tea is the solute. Water is referred to as the universal solvent, because it can dissolve almost anything. If you want to make a solute dissolve faster in the solvent, there are three things that you can do: Heat up the mixture. Crush the solute. Stir the mixture. The air that we breathe is also a solution. Most of the air in our atmosphere is nitrogen (75%), and about 23 % is oxygen. That makes nitrogen the solvent and oxygen is the solute.

45. Solutions: Concentration Which solution has the higher concentration? How do you know? 50 grams of NaCl in 100 mL of water 75 grams of NaCl in 250 mL of water

46. Solubility Curve of a Solid in a Liquid or a Liquid in a Gas SUPER-SATURATED Solubility SATURATED UNSATURATED Temperature

47. Solubility Curve of a Gas in a Liquid SUPER-SATURATED SATURATED Solubility UNSATURATED Temperature

48. Acids Acids are aqueous solutions (water) that contain extra Hydrogen Ions (H+). The extra hydrogen ions turn water molecules into hydronium (H3O+). Acids are Sour Corrosive Reactive with metals Conduct electricity Turns blue litmus paper red pH 0-7

49. Bases Bases are aqueous solutions (water) that contain extra Hydroxide Ions (OH-). Bases are Bitter Slippery Conduct electricity Turns red litmus paper blue pH 7-14

50. WEAK STRONG STRONG