pure substance states of matter solid liquid gas vapor plasma elements periodic table compounds

1. 2.1: Finding Out About Matter pure substance states of matter solid liquid gas vapor plasma elements periodic table compounds chemical names chemical symbols metals non-metals mixtures homogeneous mixtures heterogeneous mixtures solutions solute solvent alloys filtration distillation crystallization chromatography centrifuging decanting evaporation magnet physical properties chemical properties physical change phase change chemical change evidence of chemical reactions nuclear change reactant product Chemical Equation Law of Conservation of Mass Law of Definite Proportions Percent by Mass Law of Multiple Proportions

2. Define the terms mixture and compound more precisely Distinguish between elements, compounds, and mixtures Describe how elements combine to form compounds Describe the characteristics of certain kinds of chemical compounds Expand your ability to visualize the basic structures of matter List and describe several techniques used to separate mixtures.

3. Identify parts of a chemical equation. Distinguish between physical and chemical properties. Identify phase and phase change Define physical change and list several common physical changes. Define chemical change and list several indications that a chemical change has taken place. Define nuclear change. Apply the law of conservation of mass to chemical reactions. Apply percent by mass for chemical compounds. Distinguish between the Law of Definite Proportions and the Law of Multiple Proportions.

4. Do you think you see anything around you composed of just one element? Even though a few elements, such as carbon and gold, are sometimes found in elemental form in nature, most of the substances we see around us consist of two or more elements that have combined chemically to form more complex substances called compounds.

5. Pure substances – matter that always has a constant composition Examples: NaCl aka ______ H20 Tap water 5

6. To classify a sample of matter as a pure substance or a mixture, ask one or both of the following questions: Does it have a constant composition? 1) If it does, it is a pure substance. If it has variable composition, it is a mixture. 2) Can the sample as a whole be described with a chemical formula? If it can, it is a pure substance. If it cannot, it is a mixture.

7. States of Matter

8. All matter is composed of tiny particles. (We will start by picturing these as tiny spheres.) These particles are in constant motion. The amount of motion is related to temperature. Increased temperature reflects increased motion. Solids, gases, and liquids differ in the freedom of motion of their particles and in how strongly the particles attract each other. 8

9. Model of a solid at particle level 9

10. Solids • Definite shape • Definite volume • atoms tightly packed • particles vibrate • Incompressible -

11. Model of a liquid at particle level 11

12. Liquid • Indefinite shape – • Definite volume • Can flow • Less closely packed • Can move past one another • incompressible

13. Model of a gas at particle level 13

14. Gas • Indefinite shape • Indefinite volume – • Flows • Very far apart • Easily compressed • Vapor - liquid or solid at room temperature

15. Plasma • Particles have electric charges • Can conduct electricity

16. So the amount of motion of particles is proportional to _____________. 16

17. 2.2 Classification of Matter and Separating Mixtures

18. Classification Matter Pure Substance Mixtures Elements Compounds Homogeneous Heterogeneous Metals Non-Metals

19. Element – can be composed of a single atom or a group of atoms, but it is made up of only one type of atom Cannot be broken down chemically or physically Earth = 92 natural elements Not equally abundant represented by symbols

20. Relationships of Chemical Symbols to Chemical Names • Jons Berzelius used letters to represent the atoms of each element. • C - carbon • P - phosphorus • S - sulfur • With over 100 elements and only 26 letters, second letters were needed. • Usually the second letter in the name of the element, or a main consonant in the name • Full name is written with lower case letters only 20

21. Not all symbols from common English name • Many come from the Latin names • antimony, Sb stibnum • copper, Cu cuprum • gold, Au aurum • iron, Fe ferrum • lead, Pb plumbum • mercury, Hg hydragyrum • potassium, K kalium • silver, Ag argentum • sodium, Na natrium • tin, Sn stannum • tungsten, W wolfram 21

22. A compound is a substance that contains two or more elements, with the atoms of those elements always combining in the same whole‑number ratio. CANNOT be separated physically Definite ratio Can be broken down by chemical means Its properties are entirely different from the elements used to make the new compound oxygen & hydrogen vs. water New chemicals always being discovered...exciting research Represented by chemical formulas Neutral NaCl (Ionic, metal + nonmental) H2O (Molecular, nonmetal + nonmetal) CO2 _______________________________________

23. To classify a pure substance as an element or a compound, ask the following question: Can it be described with a single symbol? If it can, it is an element. If its chemical formula contains two or more different element symbols, it is a compound. Example: 3% hydrogen peroxide, H2O2, and about 97% water. Bottle of this mild disinfectant __________ hydrogen peroxide, H2O2 __________ hydrogen made to make the H2O2 _______ 23

24. The label on a container of double‑acting baking powder tells us that it contains cornstarch, bicarbonate of soda (also called sodium hydrogen carbonate, NaHCO3), sodium aluminum sulfate, and acid phosphate of calcium (which chemists call calcium dihydrogen phosphate, Ca(H2PO4)2). Classify each of the following as a pure substance or a mixture. If it is a pure substance, is it an element or a compound? a. calcium b. calcium dihydrogen phosphate c. double-acting baking powder 24

25. Metals Reflect light when polished Can be shaped High melting points Conductors of electricity Non-Metals 25

26. Mixtures: 2 or more mixed substances in no fixed ration Can be separated physically The properties are a blend of components forming the mixture Homogeneous Mixture Uniform throughout: Every sample looks the same everywhere in the mixture even under a microscope...ex. air, salt water Same properties throughout Solutions (a definition) Heterogeneous Mixture Not uniform throughout...ex. taco salad, trail mix Easiest type of mixture to separate, in fact may separate themselves. Cannot be considered a single phase. 26

27. Solution – (a type of homogeneous mixture) Solute Solvent Ex: Salt dissolved in water Carbon dioxide dissolved in pop Other Examples:

28. Alloy – a homogeneous mixture, where at least one is a metal, that have been melted together to form a uniform compound. Brass • Stainless Steel - ____, ____, ____ • Brass - ____, ____ • Gold - ____, ____, ____

29. Methods used to Separate Mixtures • Explain how each separation process works: a. filtration b. distillation c. crystallization d. chromatography e. centrifuging f. decanting g. evaporation h. magnet Are the above processes considered physical or chemical separations?

30. Filtration – uses a porous barrier to separate a solid from a liquid

31. Distillation – separates 2 things with different boiling points

32. Crystallization – formation of pure solid particles of a substance from a solution containing the dissolved substance https://www.youtube.com/watch?v=71bvKydh5gk

33. Chromatography – separates the parts of a mixture based on the ability of each part to travel across the surface of another material

34. The figure shows a paper chromatography of a mixture of pigments. Pigment ____ would have the least attraction to the paper.

35. A centrifuge is a piece of equipment, generally driven by an electric motor, that puts an object in rotation around a fixed axis, applying a force perpendicular to the axis.

36. Decanting - gradually pour a solution from one container into another, esp. without disturbing the sediment 36

37. Magnet

38. Classification of Matter • A. Pure Substance - Element • B. Pure Substance - Compound • C. Homogeneous mixture • D. Heterogeneous mixture 1. charcoal 2. oxygen 3. sulfur dioxide 4. tap water 5. hydrochloric acid HCl(aq) 38

39. 2.3 Physical / Chemical Changes and PropertiesChemical changes are chemists’ primary concern. They want to know what, if anything, happens when one substance encounters another.Do the substances change? How and why? Can the conditions be altered to speed the changes up, slow them down, or perhaps reverse them?

40. Physical Properties • Characteristic that can be observed or measured without changing the chemical composition • Examples: color, taste, texture, odor, shape, melting points/freezing points, boiling point - a pure substance boils at a constant temperature until all liquid turns to gas, density - mass per volume

41. Chemical Properties • The ability of a substance to combine with or change into one or more other substances • Magic word: Different • Burning • Iron rusting • Inert gasses

42. Physical vs. Chemical Properties of Cu

44. Physical Changes Change in appearance without change in composition Ex: change in size, shape, or in physical state ex. evaporation

45. Phase - a part of a sample with uniform composition and properties Phase change – PHYSICAL CHANGE Reversible: condensation - gas to a liquid Irreversible:

46. Chemical Changes Always produces a new substance Chemical reactions New substances have different composition, structure & properties Examples: fermenting, electrolysis, decomposition or decaying, combustion, rusting To make sure a Chemical Change has taken place: Check the composition of the sample before and after the change, there will be a change in chemical properties

47. Separating compounds – chemical process • Compounds that occur naturally are hard to separate because they are very stable

48. Evidence of Chemical Change 1. gas given off 2. color change 3. bubbles given off 4. a precipitate forms (solid which forms when substances mix)

49. KI + AgNO3 KNO3 + AgI

50. Nuclear change Involves changing one atom to a different kind of atom. A new element is formed energy exchange thousands of times greater than the energy exchanged during a chemical change 50