WELCOME TO MRS CANALE S CHEMISTRY CLASS! FIND YOUR SEAT- YOUR NAME IS ON A NOTE CARD. FILL OUT YOUR NOTE CARD AND TURN INTO TOP BIN ON FRONT DESK.

Transcription

1 WELCOME TO MRS CANALE S CHEMISTRY CLASS! FIND YOUR SEAT- YOUR NAME IS ON A NOTE CARD. FILL OUT YOUR NOTE CARD AND TURN INTO TOP BIN ON FRONT DESK. Name 1. Hobbies and activities Nick name 2. Do you have a job? And/or do you play a sport? 3. Why did you take this course. 4. What do you want to be when you grow up? 5. Last science course you took Teacher Final grade Regents grade 6. Last math course you took Teacher Final grade Regents grade 7. Math you are taking this year 8. Any information that you think I should know about you. (medical, seating, IEP, interest.)

2 Regents Chemistry

3 Chemistry is the study of matter and how it interacts with the environment Matter anything that has mass and takes up space (volume) Observation Use your 5 senses to describe an event Qualitative- a description (I.e., it s red, it s brittle, it shines) Quantitative- measurement (number, 5 cm long) Conclusion an assumption based on your observation General statement You assess everything you ve gathered and make a statement about your observations

4 Your Turn! A clear colorless liquid is combined with a second clear colorless liquid and the mixture is observed. Which of these is not an observation? a. The test tube became hot. b. The reaction is exothermic. c. The mixture is cloudy. d. The mixture is white. 1-4

5 Thinking Like a Chemist Figure 1.1 Inside a drop of lake water we find water molecules, dissolved substances and algae cells. Copyright 2011 John Wiley & Sons, Inc 1-5

6 Read the sentence in the box. Count the number of F s you see. Only read it once and do not go back. FINISHED FILES ARE THE RE- SULT OF YEARS OF SCIENTIF- IC STUDY COMBINED WITH THE EXPEREINCE OF MANY YEARS.

7 Scientific Method If experiments prove your hypothesis false, then go back and propose a new hypothesis. Observation Hypothesis Experiments Theory 5 senses Educated guess Controlled Collect data Conclusion Independent variable: the variable that scientist control and change. (x-axis) The theory is tested by further experiments and modified if necessary. Dependant variable: the variable that responds to changes in the independent variable (y-axis) Observation The same observations made over and over lead to a hypothesis Experiments Carefully designed experiments test the hypothesis. If results consistently support hypothesis, then a law can be proposed Scientific Law A generally Accepted principle

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9 The Scientific Method Law: Statements of natural phenomena to which there are no known exceptions. Hypothesis: A tentative explanation of the facts that can be tested further Theory: Well-tested hypothesis. 1-9

10 Your Turn! Which of these is a law? a. Atoms consist of protons, neutrons, and electrons. b. All matter is composed of atoms. c. Atoms can form chemical bonds by sharing electrons. d. The volume of a gas increases with increasing temperature. Copyright 2011 John Wiley & Sons, Inc 1-10

11 Your Turn! The statement, An atom consists of a dense nucleus surrounded by a cloud of electrons, is an example of a. a theory b. a law c. an hypothesis d. an observation 1-11

12 States of Matter Solid Liquid Gas definite volume definite shape regular geometric pattern crystalline structure vibrate in a fixed location strong forces of attraction Molecules farther apart definite volume no definite shape intermolecular forces noncompressible Molecules far apart no definite shape no definite volume no force of attractions Compressible Completely fills any container

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14 Classification of Matter Matter Substance contains only one element or compound Pure Definite composition homogenous Physically separated i.e., using a magnet, filtering, size separation Mixture of Substances contains two or more element and/or compounds physically associated Impure Variable composition

15 Substance Element located on PT only one type of atom smallest form is the atom can not be decomposed or broken down Monatomic made on 1 atom Na Diatomic---made of two atoms (thus di) C Chemically Separated Electrolysis, decomposition by light Compound two or more different elements chemically combined elements take on new properties in the compound smallest form is the molecule can be decomposed or broken down into its elements combine in fixed ratios H 2 O NaCl I 2 Br 2 Cl 2 F 2 O 2 N 2 H 2 Memorize these I Bring Clay From Our New Home

16 Mixture of Subs tances Hom ogeneous Mixture uniform throughout same throughout Can t tell the difference Solution: (aq) NaCl (aq)-- dissolved in water Heterogeneous Mixture nonuniform not same throughout distinct phases contains regions with different properties can tell the difference layers

17 Filtration separate large particles by using a membrane (Solids & liquids) Separating Mixtures Evaporation recover something dissolved by boiling off the solvent (water) Distillation Use to separate a mixture of Liquids Based on their boiling points Must have different boiling points Other Centrifuge (density) does not separate out dissolved particles (ions) 1. Gravity: just let mixture drip 2. Vacuum: pulls the mixture through a funnel by suction Chromatography separate dyes or pigments by size using filter paper Physically Separate by size or physical characteristic Use a magnet to separate magnetic from non magnetic Use a sieve to separate different sized material

18 Physical Property A quality or condition of a substance that can be observed or measured without changing the substance s composition Extens ive Dependent on how much is present Intens ive Does not depend on how much is present Volum e V = l x w x h Water displacement Dens ity Density = mass/volume Table T **The density for each element is listed on Table S

19 Chemical Property The ability of a substance to undergo a chemical reaction and to form a new substance. Evidence of a chem ical reaction Change in temperature (absorb or release heat) Change color Produce a gas Produce a solid (precipitate)

20 Physical Change Chemical Change A change that does not alter the chemical composition of the material. Can get the original back Results in a change in chemical composition of the substances involved. Can not get the original back Something new Phase change dissolve React burn oxidize corrode

21 Measuring Matter SI Units Prefixes mass Kilogram kg (grams) Kilo k 10 3 length Meter m hecto h 10 2 Time seconds sec deca da 10 1 Temp Kelvin K ( C) base Electric current ampheres Amount of a substance mole Pressure kilopascales kpa Atmospheres atm Energy Joules J Calories cal Table D deci d 10-1 centi c 10-2 mili m 10-3 Table C

22 Converting Measurements k h Down Right Move decimal point to the right da o Up Left Move decimal point to the left Base unit No prefix d c m Kids have dropped over dead converting metrics OR DRUL: down right up left King Henry dallied while drinking chocolate milk

23 Accuracy How close a number is to the accepted or true value. Precision How close a set of numbers are to each other repeatability Precise, not accurate Not precise, not accurate Not precise, but accurate

24 Percent Error Used to determine accuracy % Error = measured value - accepted value X 100 accepted value Table T

25 Uncertainty Always measure one place past the graduated mark. Last number in a measure is estimated, all others you know for sure The more graduated the instrument, more significant figures you will have

26 Significant Figures Decimal point Is present P 2400 A QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. Decimal point is absent 2 sig fig Draw a line until you hit your first nonzero, all digits not crossed out are significant sig fig 3 sig fig

27 Multiplication/ Division Your answer will have the same number of significant figures as the least in the problem x Answer should have 2 sig fig Addition/ Subtraction Your answer will have the same number of decimal places as the least in the problem Answer should have 2 decimal places

28 Scientific Notation. x 10 exp Number 1-9 Up to 2 digits after the decimal Some power of 10 If original number is Larger than 1 pos Less than 1 neg However many places you move the decimal