Chemistry 110 Lecture Notes. EXAM I Material. The Universe According to Physical Sciences: Chemistry: Physics: Areas of Application in Chemistry:

Transcription

1 The Universe According to Physical Sciences: Chemistry 110 Lecture Notes EXAM I Material Chemistry: Physics: Areas of Application in Chemistry: 1

2 MATH TOOLS FOR CHEMISTRY I. Scientific Notation Scientific notation is used for expressing very large or very small numbers x note: There should only be1 number to the left of the decimal place!! not x Examples: = = II. Significant Figures in Measurements (Sig. fig.) Example o T = 25 o C or o T = o C A. Significant Figures in measurements Record all certain digits plus one uncertain digit 2

3 0g 1g 2g 3g 4g 0g 1g 2g 3g 4g. The number of Sig. Fig. in measured numbers will show the uncertainty of the measuring device. B. Determining the Number of Significant Figures in a Measured value 1. All non-zero digits: are significant Example: 2. Leading Zeros: Zeros on the left side of a non-zero digit are not significant Example: 3. Captive Zeros: Zeros between non-zero digits are significant Example: 4. Trailing Zeros: Zeros on the right side of non-zero digits... a. If the number has a decimal point, the trailing zeros are significant Example: b. If the number does not have a decimal point, the trailing zeros are not significant Example: 3

4 How many significant figures do the following numbers contain? C Rounding - Off Numbers 1. If the digit to be dropped is < 5! eliminate the number [Round-down] 2. If the digit to be dropped is 5! Round-up D. Significant Figures in Calculations 1. Addition and Subtraction Answer may not have any more decimal places than the least accurate number (with the smallest number of decimal digits) 2. Multiplication and division Answer contains the same number of significant figures as the measurement with the smallest number of sig. figs. 4

5 With Complex Operations: ** [Multiplication or Division] and [Addition or Subtraction] rules are used in combination. Key: Apply the Sig. Figs. rules stepwise Example ( ) x ( ) E. Exact numbers Exact numbers are not measured numbers and have an infinite number of significant figures. Exact numbers are COUNTS. II. The International System of Meaasurements (SI) The SI is the scientific system of units of measurement Some Common SI Units LENGTH MASS VOLUME TIME Unit: meter gram liter sec Symbol: m g L s SI Prefixes SI prefixes are all related by factors of ten (are decimally based). Prefix Symbol Exponential form Standard form Meaning Terra- T ,000,000,000,000 Trillion Giga- G ,000,000,000 Billion Mega- M 106 1,000,000 Million Kilo- k 103 1,000 Thousand Deca- da Ten Deci- d Tenth Centi- c Hundredth Milli- m Thousandth Micro- µ Millionth Nano- n Billionth Pico p Trillionth 5

6 III. DIMENSIONAL ANALYSIS Dimensional Analysis is a method used to convert from one unit to another. Types of Dimensional Analysis Conversions: a) One of the units has prefix b) Both of the units have prefixes c) The units are fractional d) The units have exponents other than 1 e) c + d a) One of the units has prefix Example 1: Convert 1.77 centimeters into meters Example 2: Convert 3.2 x 10 2 ks into s b) Both of the units have prefixes Example 1: Convert 1.77 centimeters into micrometers Example 2: Convert 3.2 x 10 2 cs into Gs c) The units are fractional Example 1: How many kl is x 10 3 cl equal to? s min 6

7 Example 2: Convert 3.2 x 10 2 m into Mm. hr s d) The units have exponents other than 1 Example 1: Convert cm 2 into Tm 2. Example 2: Convert 1.2 x 10 3 ms 3 into ks 3. e) (c + d): Units are fractional and have exponents other than 1: Example 1: How many Mm s 2 is x 10 3 cm min 2 equal to? dg 1 g Example 2: Convert x into. min 3 hr 3 7

8 Volume Units in SI: 1. Liter-Based: 2. Cubed-based: How to convert between these two standards? PROBLEMS: Significant figures: Metric " metric conversion factors are exact numbers and have an infinite number of significant figures English " english conversion factors are exact numbers and have an infinite number of significant figures English " metric conversion factors are measured numbers and have a finite number of significant figures More practice problems: 1. How many millimeters are in 3.4 meters 2. How many liters in 55 µl? 3. How many Kilometers are in 3.46 x mm? 4. How many milliliters are in 1.2 x 10 6 deciliters? 5. How many milligrams in 32 lbs? 8

9 6. How many Km is a yd football field 7. What is 2.00 drams in gallons if : 1 dram = x 10-3 µl 8. If gas is 66 cents per L, what is this in dollars per gallon? 9. If a faucet is dripping at 1.0 drop per sec, how many mls per week is this? 16 drops = 1.0 ml 10. A piece of wood is 15 cm x 24 cm x 11 cm. (1) What is the volume of this wood? (2) What is the volume in cubic meters? 11. If a glass holds x 10 4 mm 3 of water, what is this in cubic inches? 12. The estimated amount of recoverable oil from the field at Prudhoe Bay in Alaska is 9.6 x 10 9 barrels. What is the amount of oil in cubic meters? [12 barrel = 42 gal (exact)] [1 qt = 9.46 x 10-4 m 3 ] 13. On the planet Aragonose (which is made mostly of the mineral aragonite, whose composition is calcium carbonate) has an atmosphere containing methane and carbon dioxide. Aragonose has an ocean and it's depth was measured to be 2425 fathoms. What is this depth in meters? (1 fathom = 6.00 ft.) 9

10 CHEMISTRY Mass and Weight Weight is the gravitational force with which a planet attracts an object (like the earth) Mass is the quantity of a matter in an object Density Density measures how closely the mass of a given substance is packed in a given volume D = Mass Volume 3 Types of Density Problems: 1. If g gold = 2.10 cm 3, what is its density? 2. Calculate the mass of 251 ml of Al. (Density of Al = 2.7 g Al / cm 3 Al) 3. What is the volume of 2.5 kg of Au? 10

11 Temperature Temperature,T o, is a measurement of hotness or coldness. A. Celsius & Kelvin B. o F C. Thermometers o F o C K D. Temperature conversions:

12 The PERIODIC TABLE of the Elements A. ELEMENTS# Memorize selected elements. Correct spelling is essential!!! B. Periods are horizontal rows on the periodic table Groups are vertical columns on the periodic table Group Name IA Alkali Metals IIA Alkaline Earth Metals VIIA Halogens VIIIA Noble Gases Families are groups (essentially). These elements have similar properities. Diatomic Elements are those elements that exists as two atoms bonded together HONClBrIF Metals are those elements which have the characteristic properities of: high luster, good conductors of heat and electricity, and are malleable Nonmetals are those elements, unlike metals do not have a high luster and generally are not good conductors of heat and electricity Transition elements (metals) are the groups 3-12 Mettaloids are elements with properities that are intermediate between those of metal and nonmetals 12

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14 MATTER-Matter is anything that occupies space and has mass. A. PHYSICAL STATES OF MATTER SOLID LIQUID GAS PLASMA Cartoon: Energy Content: S L G P Shape: Density: S L G P Ability to flow: Changes of States: Construct Chart Liquid Solid Gas Legend: = = Plasma 14

15 B. PHYSICAL PROPERTIES Each substance has a unique set of properties. Physical properties can be seen or measured with out changing the chemical composition. C. PHYSICAL CHANGES A physical change alters the physical properties of a substance without altering its chemical composition. Usually when: 1. Changing a sample of matter from one physical state to another 2. Changing the size or shape of the substance 3. Mixing or dissolving two or more substances D. CHEMICAL PROPERTIES Chemical properties are observed or measure only when it is undergoing a chemical reaction. E. CHEMICAL CHANGES A chemical change is a process that changes the chemical composition of a substance 1. Examples of chemical reactions 2. Evidence of a chemical reaction occurring 3. Chemical equations F. EXAMPLES OF PHYSICAL VS CHEMICAL CHANGES 1. Paper burns to produce CO 2 and H 2 O 2. Gasoline evaporates 3. The statue of liberty turns green 4. Tearing paper 5. A tree stump rots 6. Dissolving a package of jello in water Types of Particles A. Atoms are the smallest units/particles that can exist that will have the characteristics of the element. B. Molecules are the smallest unit of two or more atoms covalently bonded together. (more later) C. An ion is a positively or negatively charged atom or group of atoms 15

16 Types of Matter: Construct Flow Chart Scientific Law and Theory 1. Scientific Law 2. Scientific Theory Conservation of Mass In a chemical change (reaction) matter can neither be created nor destroyed. Example: Conservation of Energy Electrical Character Oppositely charged objects attract each other 16

17 Objects that are the same charge repel each other Electrostatic Force Energy - Chemical, electrical, heat or light a. Kinetic energy - Energy due to the motion of the object Examples: b. Potential energy - due to the position or chemical composition of the object c. Thermal energy (1) Endothermic Reaction - Heat is absorbed in a reaction (2) Exothermic reaction - Heat is released in a reaction 17

18 More on THE PERIODIC TABLE of the Elements Modern Atomic Theory: Subatomic Relative Charge Particle/s Mass Electron Cloud: Nucleus: * For your information: Actual mass of 1 proton: x g Actual mass of 1 neutron: x g Actual mass of 1 electron: x g Remember the definition for Atom : 18

19 Atomic Number: Symbol: Physical Meaning: Mass Number: Symbol: Physical Meaning: Remember the definition for Ion : How could an atom become charged when converted into an ion (ionized)? What are some trends in ionization? Metals: Non-Metals: More details in common trends: 19

20 Ionic Compounds: Definition: Formula: (Principle of neutrality of charge) Accepted Format: Examples: # Made with ions of Cation Formula 1 nitrogen and aluminum Anion Formula Compound Formula 2 calcium and fluorine 3 bromine and potassium 4 strontium and phosphorus 5 barium and hydrogen 6 magnesium and iodine 7 francium and sulfur 8 aluminum and hydrogen 9 oxygen and magnesium 10 oxygen and silver 11 chlorine and aluminum 12 chlorine and radium 13 rubidium and fluorine 14 lithium and sulfur 15 sodium and sulfur 20

21 Isotopes Definitions: a) b) Natural Abundance: Examples of Isotopes: a) Hydrogen Isotopic Name Hydrogen Deuterium Tritium Proton Electron Neutron Atomic Number (Z) Mass Number (A) b) Carbon Isotopic Name Carbon-12 Carbon-13 Carbon-14 Proton Electron Neutron Atomic Number (Z) Mass Number (A) c) Nitrogen Isotopic Name Nitrogen-14 Nitrogen-15 Nitrogen-17 Proton Electron Neutron Atomic Number (Z) Mass Number (A) 21

22 d) Bromine Isotopic Name Bromine-79 Bromine-81 Problems: Proton Electron Neutron Atomic Number (Z) Mass Number (A) 1. What is the isotopic symbol of a neutral element with 3 more protons and 3 more neutrons than V-51? 2. What is the isotopic symbol of an anion with 2 more protons, 4 more neutrons, same number of electrons as Si-28? 22