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    Chemistry Notes

    Chapter 1 Chemistry: The central science

    1. 1.1 The study of Chemistry

    a. Chemistry : is the study of i. Compositionii. Structure

    iii. Propertiesiv. Changes in Matter

    b. Matter : is anything that has mass and takes up spacec. Atoms : smallest building blocks of matterd. Properties of matter depend on

    i. Kinds of atoms it contains composition

    ii. Ways atoms are arranged structuree. Millions of different materials are knownf. They are made up of about 100 different known atomsg. Different kinds of atoms come from different elementsh. Only 118 different elements are knowni. Each element has a name and a symbol j. Symbol shorthand notation: 1 or 2 letters (First letter capitalized)k. Molecule 2 or more atoms attached to each other in a specific wayl. Chemistry is an experimental science

    m. Knowledge of the facts of chemistry is obtained by

    i. Doing experimentsii. Making observations

    n. Our findings are called data or factso. Data or Facts are systematically orderedp. Scientific law

    i. Summarizes what consistently happens in natureii. Can be used to make predictions

    q. Scientists try to explain why and how something happensr. Hypothesis

    i. Tentative explanation of what is observedii. Is tested by doing more experiments

    iii. May have to be modified and retesteds. Theory an explanation that is extensively tested and generally acceptedt. The scientific method : the way scientists

    i. Gather data from experiments and observations

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    ii. Develop scientific laws, hypothesizes, and theories

    2. 1.2 Classification of Matter

    a.

    Classification of matteri. By its physical state1. Solid2. Liquid3. Gas

    ii. By its composition1. Mixture2. Pure substance

    b. States of matteri. Solid

    1. is rigid has a definite shape and definite volume2. Molecules touch cannot move

    ii. Liquid1. Has a distinct volume2. But no definite shape3. Molecules touch and can move

    iii. Gas1. No fixed volume or shape2. Can be easily compressed3. Molecules far apart

    c. Mixtures and Pure substancesi. Mixture

    1. Consists of 2 or more pure substances2. Have variable compositions3. Can be separated by physical means4. Each component keeps

    a. Its chemical identiyb. Its properties

    d. Heterogeneous mixture not uniform thoughoute. Homogenous mixture - uniform throughout also called solutionf. To separate mixtures use properties of components

    i. Muddy water (Het. Mix.) filtrationii. Salt water ( sol.) distillation

    iii. Iron/sugar mix (Het. Mix.) magnet removes iron water dissolves sugar

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    g. Pure substances have a fixed composition and distinct propertiesi. 2 classes:

    1. elements2. compounds

    h.

    Elementsi. Composed of only one kind of atomii. Cannot be decomposed into simpler substances

    iii. 118 knowni. Compounds

    i. Composed of 2 or more atomsii. Formed from elements in chemical reaction

    iii. Have constant composition3. 1.3 Scientific Measurements

    a. A measurement consists of i. The measured numberii. The unit

    b. System of unitsi. British system i. Used in the U.S.i. Metric system . Used by the rest of the

    world. International system (SI) i. Subsystem of metric

    systemi. Used in the sciences

    viii. Advantage of using metric units and SI systems1. Smaller/ Larger units differ from each other by powers of 10

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    c.

    3 temperature scalesi. Fahrenheit scale water freezes at 32F and boils at 212Fii. Celsius scale water freezes at 0C and boils at 100C

    iii. Kelvin scale water freezes at 273 K and boils at 373 K1. 2. 3. ( )

    4. ( )

    d. Derived SI units obtained by combining basic SI units

    e. Volume space occupy an objectf. SI unit: 1 cubic meter, 1 m 3 very large 246 Gallonsg. Smaller unit : 1 cubic decimeter, 1 dm 3 = 0.1 m or 1 Literh. Units to describe measurement

    i. cm 3 for solidsii. mL for liquids

    i. to measure volumes we use:i. graduated cylinderii. pipets

    iii. buretsiv. Volumetric Flasks

    j. Densityi. Indicates how heavy or light a substance isii. Defined as mass per unit d =m/v

    iii. Other equations dv = m and v = m/div. Used to characterize and identify substances

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    v. Changes with temperatures; usually given at 20Cvi. Listed in tables for various substances

    4. 1.4 The Properties of mattera. Physical and chemical changes

    i.

    Physical change1. A substance changesa. Its physical appearanceb. Not its chemical composition

    2. Examplesa. Melting iceb. Evaporation of waterc. All changes of state

    ii. Chemical change or chemical reactions1. Substances converted to chemically different substances2. Examples

    a. Burning of hydrogen in air to get waterb. Burning of natural gas or methane

    b. Properties of matter are used to characterize and identify substancesc. Physical properties do not involve chemical reaction

    i. Melting pointii. Density

    d. Chemical properties involve a chemical reactioni. Oil burnsii. Iron rusts

    5. Appendix 1 Scientific Notationa. Exponential notationb. Useful for: expressing a very small or very large numbers indicates the number of

    significant figuresc. A number is written as a small number times a power of 10d. Standard exponential notation is 1 digit term < 10 e. Adding and subtracting with scientific notation

    i. Convert to some power of 10ii. Add or subtract the digit terms, keep exponent term

    iii. Facelift if neededf. Multiply with scientific notation

    i. Multiply the digit termsii. Add the exponents

    iii. Facelift if necessary

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    g. Dividing with scientific notationi. Divide the digit termsii. Subtract the exponents

    iii. Facelift if necessary

    6.

    1.5 Uncertainty in Measurementa. A measurement consists of i. The measured numberii. The unit

    iii. An indication of the uncertaintyb. Precision closeness among a set of measured valuesc. Accuracy closeness of a measurement to the true averaged. To indicate uncertainty in a measured value, we use significant figurese. Significant figures

    i. All the digits that are certain plus one that contains a slight uncertaintyii. How many significant digits are there in a number?

    1. All non-zero digits are significant2. Zeroes between non-zero digits are significant3. Zeroes before the first non-zero digits are not significant4. Zeroes after the last non zero digit are significant5. In the numbers without a decimal point: zeroes after the last non-

    zero digit may or may not be significant we use scientific notationto avoid ambiguity

    f. Calculations with significant figuresi. Rule for multiplication/division

    1. In the product or quotient keep only as many significant digits asthere are in the term with the smallest number of significantdigits

    ii. Rule for addition/subtraction1. The last digit retained in the sum or difference should correspond

    to the first column that contains slight uncertaintyiii. Rounding

    1. Simply drop numbers smaller than 52. Increase the last digit if the first digit dropped is larger than 5

    iv. Calculations involving 2 or more steps1. For each step use the appropriate rule2. Do not round intermediate results rather underline the last

    significant digit3. Round the final result to the correct number of significant figures

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    7. 1.6 Using units and solving problemsa. Dimensional analysis or Factor label method or Unit factor Method

    i. Used to make conversions from one unit to another oneii. Advantages

    1.

    Supplies numbers and correct units2. Makes errors easy to spotb. Hints

    i. Design the conversion factor in such a way that units you want to get ridof will cancel out

    ii. Multiply and divide1. Not only the numbers2. But also the units

    iii. Check to see if your answer makes senseiv. Use a road map

    Chapter 2 Atoms, Molecules, and Atoms

    8. 2.1 The Atomic Theorya. Daltons atomic theory all matter consists of atoms that are tiny invisible

    particlesb. Elements composed of atoms of only one kindc. Atoms of

    i. The same element are identical

    ii.

    Different elements differ from each otherd. In a chemical reaction atoms are regrouped atoms are neither created or

    destroyed this explains the law of conservation of mater or in a chemicalreaction the total mass of the products is equal to the total mass of the startingmaterials

    e. Compoundi. Formed when atoms of 2 or more elements combineii. Always has the same relative number and kind of atom

    f. This explains the law of constant compositioni. Any compound is always made up of the same elements in the same

    proportion by massg. Dalton deduced the law of multiple proportions

    i. When 2 elements form more than one compound the masses of oneelement that are combined with a fixed mass of the other element ar inthe ration of small whole numbers

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    9. 2.2 The Structure of an atoma. Subatomic particles: protons, neutrons, and electronsb.

    c. Particle d. Location e. Mass(amu)

    f. Rangefrom the center

    g. Proton h. In nucleus i. 1.00725 =1 j. 1k. Neutro

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