Chemistry Notes

1. Chemistry Notes Alexander Crumpton Fuqua

2. 8.P.1.1 MATTER

3. Atoms are the building block of matter • Atoms are made up of three subatomic particles. • Protons • Positive Charge • Found in the nucleus • Neutrons • Neutral (No charge) • Found in the nucleus • Electrons • Negative charge • Found around the nucleus on energy levels (orbitals)

4. States of Matter • Solids • Atoms are locked in position, can only vibrate • Liquids • Atoms and molecules can collide with and move past one another • Gases • Atoms and molecules move independently, colliding frequently • As energy (heat) increases the molecules move more (solidliquidgas) • As energy (heat) decreased the molecules slow down (gasliquidsolid)

5. Matter – anything that has mass and occupies space • All the “stuff” around you is matter.

6. Elements are a pure substance that can not be broken down into any other substance. • Composed of one kind of atom

7. COMPOUNDS- a pure substance made up of two or more substances chemically combined • Can only be broken down into simpler substances through chemical changes

8. Mixtures are two or more substances mixed together, not chemically combined • Mixtures are easy to separate into different parts because the parts keep their properties. • 3 ways to separate mixtures • Filtration • Separation • Evaporation

9. Types of Mixtures • Heterogeneous Mixtures • Not uniform throughout • The different components can be identified • Examples: salad, granite, iced tea, trail mix • Homogeneous Mixtures • Uniform throughout • Evenly mixed • Examples: air, steel, salt water • Also known as a solution

10. 8.P.1.2 PERIODIC TABLE

11. Dmitri Mendeleev is credited with the creation of the modern periodic table • Elements on the periodic table are arranged horizontally in periods/rows according to atomic number • Families and groups run vertically and share similar properties • Atomic number = # of protons = # of electrons • Atomic Mass = # of protons + # of neutrons • To find the number of neutrons, take the atomic mass and subtract the atomic number

12. Families on the Periodic Table • Elements on the periodic table can be grouped into families bases on their chemical properties. • Each family has a specific name to differentiate it from the other families in the periodic table. • Elements in each family react differently with other elements.

13. ALKALI METALS Group 1 • Hydrogen is not a member, it is a non-metal • All are metals and solid at room temp • 1 Valence Electron • Soft and silvery, shiny • Very reactive, esp. with water • Conduct electricity

14. ALKALINE EARTH METALS Group 2 • Metals • Solids at room temp • 2 electrons in the outer shell • White, silvery, and malleable • Reactive, but less than Alkali metals • Conduct electricity

15. TRANSITION METALS • Metals • Almost all are solids at room temp (Hg) • Good conductors of heat and electricity. • 1 or 2 Valence Electrons • Less Reactive than Alkali and Alkaline Earth • Can bond with many elements in a variety of shapes. • Most common elements

16. BORON FAMILY Group 13 • 3 valence electrons in the outer shell • Most are metals • Boron is a metalloid • Reactive • Solid at room temp

17. CARBON FAMILY Group 14 • 4 valence electrons in the outer shell • Contains 3 metals, 2 metalloids, and 1 non-metal Carbon (C) • Reactivity varies • Solids at room temp

18. NITROGEN FAMILY Group 15 • 5 valence electrons in the outer shell • Can share electrons to form compounds • Contains 2 metals, 2 metalloids, and 2 non-metals • Reactivity Varies • Nitrogen is the only gas at room temp, rest are solids

19. OXYGEN FAMILY Group 16 • 6 valence electrons in the outer shell • Contains 2 metals, 1 metalloid, and 3 non-metals • Reactive • Oxygen is a gas, the rest are solids at room temp

20. Halogens Group 17 • 7 valence electrons in the outer shell • Non-metals • Very reactive - are often bonded with Group 1 Alkali Metals • Has 2 gases, 1 liquid (Br), and 2 solids

21. Noble Gases Group 18 • Exist as gases • Non-metals • 8 electrons in the outer shell = Full • Helium (He) has only 2 electrons in the outer shell = Full • Not reactive with other elements (Inert)

22. Rare Earth Metals (Lanthanides & Actinides) • Some are Radioactive • The rare earths are silver, silvery-white, or gray metals. • Conduct electricity

23. Metals • Most of the periodic table, located left of the staircase • Properties of metals: • Shiny/Luster • Malleable: able to be hammered and rolled into flat sheets or other shapes • Ductile: able to be pulled into long thin wires • Conductivity: able to transfer electricity or heat • Magnetic: (Fe, Co, Ni) • Reactivity: ease or speed with which an element combines with other elements

24. Bonding Families • Bonding occurs with the electrons in the outer most shell of the element. • Remember that the first electron ring can hold 2 electrons • the second can hold a maximum of 8. • 8 is the magic number. • The usual bonding partners: • Group 1  Group 17 • Group 2 Group 16 • Group 13 Group 15 • Group14 Group 14

25. Types of Bonding • Covalent Bonding: when two or more atoms share electrons. Strong bonds • Examples: • Water • Carbon Dioxide • Ionic Bonding: When two or more atoms gain or lose electrons. Occurs between metals and nonmetals. Weaker than covalent bonds. • Examples: • NaCl: sodium chloride (table salt) • LiF: Lithium fluoride (used in radiation detection) • Gaining Electrons  More Negative = Reduction • Losing Electrons  More Positive = Oxidation

26. Non-metals • Located to the right of the staircase • The solid non-metals are: • Dull • Brittle • Poor conductors of electricity and heat • Reactive with other elements (readily form compounds)

27. Metalloids • Located on the staircase • Have characteristics of metals and non-metals • Varying ability to conduct electricity • Used to make semi-conductors • Conduct electricity under some conditions but not others (computer chips, transistors, lasers)(Si, Ge, As)

28. Chemical symbol. • First letter is always capitalized, second is lowercase • Chemical formula • Made from the symbols of elements in substance • For example: • Water has the formula H2O There are two elements H and O. • Hydrogen has 2 molecules and Oxygen has one molecule shown by the subscript. • If a coefficient is written in front of the compound everything is multipled by that coefficient. • Example: H2O is Two H and One O…BUT 2H2O would be 4 H and 2 O because we multiplied the compound by the coefficient 2.

29. Naturally Occurring Substances - substances found in nature. Elements #1-92 • Iron • Uranium • Citric Acid • Glucose • Proteins • Synthetic substances are man made. Elements #93+ • Plastics • Glue • Polyester • Chewing Gum

30. Chemical Formulas • Chemical Formula: shorthand way using chemical symbols and numbers to show a substance • H2O= • CO2 = • HCl = • Coefficient: number placed in front of chemical symbol or formula to show amount of element. • 2H2O =

31. Naming Compounds • Guideline 1: • The element on left is named first • Element on the right add the suffix “-ide” • Examples: • NaCl • MgO

32. Prefixes • Mono -1 • Di - 2 • Tri - 3 • Tetra - 4 • Penta - 5 • Hexa - 6 • Hepta - 7 • Octa - 8 • Nona - 9 • Deca - 10

33. Naming Compounds • Guideline 2: • When 2 or more compounds have different numbers for the same element, prefixes are used. • The prefix is usually left off the first word • Examples: • CO • CO2 • Sr3P2

34. Common Substances • H2O : Water • CO2 : Carbon Dioxide • C12H22O11 : Sucrose • NaCl : Table Salt • O2 : Oxygen • NaClO : Bleach • HCl : Hydrochloric Acid • NH3 : Ammonia • NaHCO3 : Baking Soda • HC2H3O2 (5% solution) : Vinegar

35. 8.P.1.3 PHYSICAL AND CHEMICAL CHANGES AND PROPERTIES

36. Physical Properties can be observed and measured WITHOUT turning it into another substance. • Can observe using the five senses • Examples are: • Shape • Density • Solubility • Odor • Melting Point • Boiling Point • Color

37. Melting Point: • Temperature at which a solid becomes a liquid • Ice melts to form liquid at 0oC (32oF) • Boiling Point: • Temperature at which a liquid boils • Changing from a liquid to a gas • Pure water at sea level boils at 100oC (212oF) • Density • Relationship between mass of a material and its volume • Will stay the same no matter how large or small the sample (Intensive Property) • Color

38. Chemical Properties: can be recognized only when substances react or do not react chemically with one another • You change it into something else, a new kind of matter. • Example: • Reacting with oxygen • Burning (Combustible): produces light and heat • Rusts • Apple turning brown • Reacting with Acids • Bases react with acid to form water and neutralize

39. PHYSICAL CHANGES • A substance that undergoes a physical change is still the same substance after the change. • A physical change changes the way matter looks. It does not change the matter into a new kind of matter. • Examples of Physical Changes: • Cutting your hair. • Mowing the grass • Boiling water • Freezing water • Melting ice • Dissolving sugar • Bending a paper clip • Sublimation

40. Chemical Changes • A chemical change produces NEW SUBSTANCES with properties different from those of the original substance. • Color Change • Temperature Change • Formation of a precipitate • Formation of a Gas

41. Color Change: • Rusting iron • Apples turning brown • Marshmallows turning black • Temperature Change • Wood burns to ash and gases • Formation of a precipitate • When two solutions combine, they may form a solid substance. • Formation of a gas • When solid or liquid substances combine, they may form gas bubbles • Vinegar with baking soda

42. Examples of Chemical Changes: • Burning wood • Rusting a car bumper • Silverware that has tarnished. • Explosion of fireworks • Lighting a match • Roasting a marshmallow • Rotting of fruit • Milk that is soured

43. Chemical Reactions • Every chemical or physical change in matter includes a change in ENERGY (usually in the form of heat) • Energy- the ability to do work • Exothermic Reaction: Reaction which gives off heat to the surroundings • Examples: • Combustion • Composting • Making Ice • Candle Flame • Endothermic Reaction: reaction which takes in heat to be completed • Examples: • Melting • Evaporating • Cooking

44. Chemical Reactions • Reactions occur at different rates • Rates can be changed by: • Changing the concentration of reactants • The temperature • Surface area of the solids • Using a catalyst • Catalyst: substance used to speed up the rate of a reaction • Unlike an inhibitor, which slows down the rate of the reaction

45. 8.P.1.4 BALANCING CHEMICAL EQUATIONS

46. Chemical Equation 2H2 + O2 2H2O • Reactants: substances broken apart of combined in a chemical reaction • Products: new substances formed in a chemical reaction • Yields: shows direction of reaction • Subscript: shows # of atoms present, written to the right and below the element • Coefficient: # of molecules present, written in front of element or compound.

47. Equations • 2 Cu + O2 2 CuO • K + H2O  H2 + KOH Why is the second reaction incorrect?

48. Law of Conservation of Mass • This law states that mass cannot be created or destroyed in ordinary chemical and physical changes. • K + H2O  H2 + KO • The total mass for the reactants equals the total mass of the products

49. Balancing Equations • Each element appears in equal amounts in products and reactants • 2 H2 + O2 2H2O • Unbalanced equations are balanced by changing coefficient, NOT subscript.

50. To Balance an Equation • Count up the amount of elements on each side. • Focus on one at a time, starting with the left-most. • Change coefficients in order to balance • Continue balancing from left to right • Balance the following Equation: MnCl2 + Al Mn + AlCl3