Prefixes: What is the exponent form?

Transcription

1 Prefixes: What is the exponent form? kilo = 1000 times base unit = 1 kg = 1000 g = 10 3 g deci = 0.1 times the base unit = 1 dl = 0.1 L = 10-1 L; 1 L = 10 dl centi = 0.01 times the base unit = 1 cm = 0.01 m = 10-2 m; 1 m = 100 cm milli = times the base unit = 1 mg = g = 10-3 g; 1 g = 1000 mg micro = times the base unit 1 μm = 10-6 m; 10 6 μm = 1 m nano= times the base unit 1 nl = 10-9 L; 10 9 nl = 1 L 24 Convert 325 ml to L (liters) Convert g to ng (nanogram) L 5.01 x 10 7 g 36 Big numbers: 12,340,000 Writing Numbers in SN Example Counting Sig. Fig. in a Number How many significant figures are in each of the following numbers? Small numbers: m = 1000 mm x x

2 Practice: How many SF and DP in measurement? Sig. Fig. in Multiplication/Division: SF When multiplying or dividing measurements with Sig. Fig., the result has the same number of SF as the measurement with the fewest number of sig. fig. Round off: , = = Add trailing zero: = 0.02 = Use scientific notation for large numbers ,103 = = Practice: Complete the following calculation with proper Sig. Fig = = = 1.5 = Sig. Fig. in Addition/Subtraction: DP when adding or subtracting measurements with significant figures, the result has the same number of decimal places as the measurement with the fewest number of decimal places = = ,250. = 75,000 = = 0.9 =

3 Practice: Complete the following calculation with proper Significant Figures = = Sig. Fig. in Combined Calculations (PEMDAS) Keep one more SF than needed and round in the End Do and/or, then + and/or = = = = -8 = Parentheses (): Do calculation in ( ) first, then the rest ( ) = = = Practice: Calculation with Proper Significant Figures a x = = The lovely practice: Convert 7.8 km to miles Given: 7.8 km Find:? mi Conv. Fact. 1 mi = 5280 ft 1 foot = 12 in 1 in = 2.54 cm (exact) Soln. Map: km mi = 4.8 mi

4 Real world Dimension Analysis: Jason decided to swim to Catalina Island. As part of the training he decided to swim for 90 minutes a morning, 6 mornings each week. He swam at an average speed of 2.0 miles per hour. At the end of eight weeks, how many miles has Jason swim? Given: 90 min = 1 day 6 days = week 2 mi = 1 hour Find:? mi over 8 weeks (mi/8 wk) Conv. Fact: 60 min = 1 hr Fahrenheit vs. Celsius a Celsius degree is 1.8 times larger than a Fahrenheit degree the standard used for 0 on the Fahrenheit scale is a lower temperature than the standard used for 0 on the Celsius scale From Celsius to Fahrenheit: From Fahrenheit to Celsius: The Kelvin Temperature Scale Kelvin scale is an absolute scale, meaning it measures the actual temperature of an object 0 K = Absolute Zero: all molecular motion would stop, theoretically the lowest temperature in the universe 0 K = -273 C = -459 F Absolute Zero is a theoretical value Conversion in Temperature Scales: Convert 104 F into Celsius and Kelvin Information Given: 104 F Find:? C,? K Eq ns: Conection between K and C: C 313 K 66 4

5 Test results Given: Mass = 5.84 grams Volume = cm 3 Density Pt = 21.4 g/cm 3 Find: Density in grams/cm 3 Density as a Conversion Factor The gasoline in an automobile gas tank has a mass of 60.0 kg and a density of g/cm 3. What is the volume? Given: 60.0 kg Find: Volume in L Conversion Factors: grams/cm grams = 1 kg Example: A 55.9 kg person displaces 57.2 L of water when submerged in a water tank. What is the density of the person in g/cm 3? Information: Given: m = 5.59 x 10 4 g Find: density, g/cm 3 Solution Map: m,v D Equation: Volume = 5.72 x 10 4 cm 3 = g/cm

6 Example: How many protons, neutrons, and electrons in an atom of U Isotopic symbol element atomic number #p #e #n Electron Configuration of Atoms in their Ground State Electron configuration: a listing of the subshells in order of filling with the number of electrons in that subshell written as a superscript Rb = 37 electrons = #proton = #neutron = #electron = 13 a shorthand way : use the symbol of the previous noble gas in [] for the inner electrons, then just write the last set Rb = 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 1 44 Order of Subshell Filling in Ground State Electron Configurations Example: Electron Configuration and Orbital Diagram of Sulfur Atom 1. Diagram putting each energy shell on a row and listing the subshells, (s, p, d, f), for that shell in order of energy, (left-to-right) 2. draw arrows through the diagonals, looping back to the next diagonal each time 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 7s How to write electron configuration? First count the number of electrons in the atom Fill each subshell until full (s = 2, p = 6, d = 10, etc), starting from 1s

7 Metal Cations with Fixed Charge Monatomic Nonmetal Anion (A n- ) only have one possible charge How much is the charge? the position on the Periodic Table Name of the anion: ending with ide Charge by position on the Periodic Table IA = +1, IIA = +2, Ag + (IB), Zn 2+ (IIB) Al 3+ (IIIA) Name is the same as the element Ag + : silver ion Ca 2+ : calcium ion 13 5A = -3 6A = -2 7A = -1 Nitride = O 2- = Fluoride = P 3- = Sulfide = Cl - = 16 Metal Cations with Variable Charges Common Examples: Fe 2+/3+, Cu +/2+, Cr 3+/6+, Mn 2+/4+, Mn 2+/4+, Pb 2+/4+, Sn 2+/4+, etc ) Name with Roman numeral to indicate charge Net charge of Ionic Compound = 0 Net charge = Positive charge from Cation(s) + Negative charge from Anion(s) = 0 Cu + : Pb 4+ : Example: Compound Al 2 S 3, the Net charge Or use common name (lower charge ous, higher charge ic ) Cu + : cuprous Cu 2+ : cupric Fe 2+ : ferrous Fe 3+ : ferric 14 = 17 1

8 How to find the charge on metal ions with variable charge? Example: Find the charge of metal in Fe 2 O 3 Since the sum of all charges equals zero, the charge on iron ions are unknown and oxide ion has 2 charge, then we have Group Practice: Naming Ionic compounds HgF 2 CuI 2 Cr 2 S 3 SnCl 4 Mg 3 N 2 Hg 2 Cl 2 Key: knowing the charge on ANIONs! Example: Naming variable charge metal compound Fe 2 O 3 1. Identify the compound as ionic or covalent 2. Identify the metal ion as fixed charge or variable charge. 3. Find the charge of metal ion using the charge on the known anion Note: What is the name and charge of anion O? 4. Name accordingly. Polyatomic Anions: -ATE ions carbonate nitrate phosphate sulfate chlorate SeO 2-4 selenate bromate iodate

9 Example Naming Ionic with Polyatomic Ion Na 2 SO 4 1. Ionic or covalent compound? 2. Ionic: fixed charge or variable charge metal cation? 3. fixed charge metal cation: Name accordingly. Practice: Naming Ionic compounds Hg 2 SO 4 CuClO 3 Zn(NO 3 ) 2 FeCO 3 Sn(SO 3 ) 2 CoPO Example Naming Ionic with Polyatomic Ion Fe(NO 3 ) 3 1. Ionic or covalent compound? 2. Ionic: fixed charge or variable charge metal cation? 3. Variable charge metal cation: determine the charge based on the charge of anion Note: what is the name and charge on NO 3? 4. Name accordingly. Write Chemical Formula using the charge of known ions Criss-Cross-Simplify : The charge of an ion turns into the subscript (the number) of the counterpart ion Pb 4+ O 2 Since the subscripts in an ionic compound represents the RATIO among the ions, the subscripts need to be simplified when there is common denominator Pb 2 O

10 Write Chemical Formula using the charge of known ions Example: Compound between Ca 2+ and PO Practice: Write Chemical Formulae Cesium phosphate Lead(II) oxide Zinc nitrate Iron(III) sulfite Strontium nitride Ammonium carbonate 41 4