Name:_KEY________________________________________________________ A. SCIENTIFIC (EXPONENTIAL) NOTATION Scientific notation uses powers of ten to express very large or very small numbers. Numbers expressed in scientific notation have a single digit, followed by a decimal and the remainder of the digits. The number is then multiplied by a power of ten. The exponent is determined by the number of times the decimal must move to be in this position. Numbers greater than one have a positive exponent, and numbers between zero and one have a negative exponent. Example: 5,450g = 5.450 x 103g 0.00027 = 2.7 x 10-4g TRY: CONVERT BETWEEN SCIENTIFIC NOTATION AND STANDARD NOTATION: a. 465mL = ___4.65x102_______________ mL g. 0.000 000 000 440 mg = __4.40x10-10________mg b. 69,755g = __6.9755x104______________ g h. 5.50 x 103 L = ____5500____________________L 234,241 J = __2.34241x105____________J i. 2.75 x 106 J = ____2,750,000_________________J c. d. 750,000,000,000g = _7.5x1011__________g j. 3.5 x 10-2 cal = ________0.035_______________cal e. 0.0125 cm3 = ____1.25x10-2___________cm3 l. f. 2.29 x 10-6 g = _____0.00000229______________g 0.000086 kPa = __8.6x10-5______________kPa On many calculators, the power of ten is written as E or EE, or the exponent is separated from the rest of the numbers. Try dividing one by 500,000,000 (1 ÷ 500,000,000) on your calculator. What do you see? ____________________________. This can be rewritten as __________________________ or ____________________________. ENTERING NUMBERS IN SCIENTIFIC NOTATION INTO YOUR CALCULATOR: To enter numbers into your calculator in scientific notation, use the EE or EXP key on your calculator. Enter the base number, then EE or EXP, followed by the exponent. DO NOT USE THE 10^ KEY! (on the graphing calculator, the EE is shift ,) TRY: ENTER THE FOLLOWING QUANTITIES INTO YOUR CALCULATOR: a. 4.51 x 1021 b. 6.02 x 1023 1 b. 9.86 x 10-13 1 mole = molar mass (look it up on the PT!) MASS (g) MOLE 1 mole = 6.02 x 1023 atoms PARTICLES (ATOM) MOLAR MASS AND MOLE CONVERSIONS Mole: 1 mole = 6.02 x 1023 Avogadro’s number: 6.02 x 1023 atoms = 1 mole (Amadeo Avogadro) Atoms, particles, molecules, formula units 11 Molar Mass: Periodic table the mass of of 1 mole of an element (in grams) Molar mass of Na is 22.99 g/mol Na 22.9897 CONVERSION FACTORS: 1 mole = 6.02 x 1023 atoms 1 mole = atomic mass (g) Try: 1. How many atoms are in 6.5 moles of zinc 6.5 moles Zn 6.02 x 1023 atoms Zn = 3.91 x 1024 atoms Zn 1 mole Zn 2. How many moles of argon are in a sample containing 2.4 x 1024 atoms of argon? 2.4 x 1024 atoms of argon 1 mole 6.02 x 1023 atoms = 3.99 mol 1 mole 6.9 g = 0.36 mol 55.8 g 1 mole = 267.84 g 3. How many moles are in 2.5g of lithium? 2.5 grams Li 4. Find the mass of 4.8moles of iron. 4.8 moles 2 CONVERSION FACTORS: 1 mole = 6.02 x 1023 atoms 1 mole = atomic mass (g) Two Step Problems: 1. What is the mass of 2.25 x 1025 atoms of lead? 2.25 x 1025 atoms of lead 1 mole 6.02 x 1023 atoms 207.2g 1 mole = 7744.19g = 7740g = 3.06 x 1022 atoms 2. How many atoms are in 10.0g of gold? 10 g gold 6.02 x 1023 atoms 1 mole 1 mole 197.0g PRACTICE PROBLEMS: a. Convert to moles: 1. 625g of copper 625g of copper 1 mol 64 g Cu = 9.77 mol Cu 2. 4.25 x 1026 atoms of barium 4.25 x 1026 atoms of barium 1 mol = 6.02 x 1023 atoms 706 mol Ba b. How many atoms are in: 1. 2.35 moles of carbon 2.35 moles 6.02 x 1023 atoms 1 mole = 1.41 x 1024 atoms 2. 4.0g of potassium 4.0 g 3. 6.02 x 1023 atoms 1 mole = 6.2 x 1022 atoms 1 mole 55.8g 6.02 x 1023 atoms 1 mole = 1.0 x 1026 atoms 9500g of iron 9500 g Fe 3 1 mole 39.1g CONVERSION FACTORS: 1 mole = 6.02 x 1023 atoms 1 mole = atomic mass (g) c. Determine the mass of: 1. 0.250 moles of aluminum 0.250 moles 27.0g = 1 mole 6.75 g Al 2. 3.48 x 1022 atoms of tin 3.48 x 1022 atoms 3. 1 mole 6.02 x 1023 atoms 118.7g 1 mole 4.48 x 1021 atoms of magnesium - report your answer in regular and scientific notation 4.48 x 1021 atoms 1 mole 6.02 x 1023 atoms 24.3g 1 mole d. Try: How many moles is 2.50kg of lead? Find the mass, in cg, of 3.25 x 1021 atoms of lithium 4 = 6.86 g Sn = 0.181 g Mg or 1.8 x 10-1 SCIENTIST NOTES NAME JOHN DALTON J. J. THOMSON CONTRIBUTION/EXPERIMENT Atomic Theory: 1. All matter is made of atoms (atoms are indivisible and indestructible) 2. All atoms in an element are identical to each other in mass and properties 3. Compounds are formed by a combination of 2 or more different kinds of atoms in different ratios 4. A chemical reaction is a rearrangement of atoms 5. In reactions, matter is neither created or destroyed (law of conservation of matter) Discovered electrons Used cathode rays to show how electrons were deflected by magnetic forces ERNEST RUTHERFORD NIELS BOHR 5 Gold Foil experiment – proved nuclear form Discovered a positively charged nucleus (99.9% of mass of atom) Atoms are mostly made up of empty space Discovered electron motion Said that electrons orbit around the nucleus Light emissions (next chapter!) MODEL Solid Sphere – “Billiard Ball Model” -different atoms were drawn at different sizes - Negative electrons set in a sponge of “+” charge -“Plum Pudding” Model - “Nuclear” Model - Protons in nucleus with electrons floating outside nucleus - “Solar System” Model