Chemistry 1364
General Chemistry I

Chapter 1 - Introduction



n    Study of matter and the changes that matter can undergo

n    Matter

n    Has mass/occupies space

n    3 phases

n    solid

n    gas

n    liquid (intermediate)


n    Substance

n    fixed composition

n   Au, H2O, C6H12O6

n    distinct properties

n   melting point, color, vapor pressure

n    The two categories of matter are an element or a compound (more later)

n     Two types of properties to describe matter

n    physical

n    no rearrangement of the atoms

n    chemical

n    atoms will rearrange to form new substances

n     Changes

n    physical

n    chemical

n    Mixtures

n    heterogeneous

n    homogeneous (solutions)

n    can be of any phase


n   filtration

n   distillation

n   chromatography

Problems 1, 3, 5

Elements and Compounds

n    Elements - cannot be decomposed by CHEMICAL means.

n    'Building blocks' of the universe

n    Abbreviated by symbols (Table 1.2 - know)

n    Compounds  - decomposed by chemical means to elements/other compounds.

n    Law of constant composition

n   All samples of a compound will have the same elements in the same ratio

Problems 7, 9, 11, 13, 15

Units of Measurement.

n     Metric system - basis for SI system

n    Units based on measurements of Earth

n    Meter based on distance from equator to North Pole

n    Heat based on energy to change water

n     SI system

n    Divides units into ‘base’ and ‘derived’

n    Seven ‘base’ units

n    All other units are a combination of the ‘base’ units

Base Units

n    Mass (kg)

n    Length (m)

n    Time (s)

n    Electric current (A)

n    Temperature (K)

n    Luminous intensity (cd)

n    Amount of substance (mol)

n    All other units - derived units

n    volume ( length3 )

n    weight [ mass * length /  time2 ]

n    density ( mass /  volume )

n    etc...


n    Defined decimal amount of unit

n    kilo - unit x 1000

n    centi - unit x 0.01

n    Know prefixes from Terra to femto

n    know both abbreviation and unit

n    milli-

n   abbreviation is m

n   multiply base unit by 0.001

n    Difference between MASS and WEIGHT.

n    Mass is a base unit

n    Weight is a derived unit (mass x acceleration)

n   Mass will not change with change in the gravitational field, but an object may become ‘weightless’


n    Metric - Celsius (non SI unit)

n    0 (freezing) to 100 (normal boiling) to define step size

n    SI - Kelvin

n    same 'step size' as Celsius

n    starting point is absolute zero

n    K = OC + 273.15

n    only correct for starting point!


n     English - Fahrenheit

n    Different step size (180 OF from freezing to boiling)

n    Different starting point (32 OF = 0 OC)

n    Must make TWO conversions

n    Step size
n    Starting point

n     OF = [(180/100) x OC] + 32OF

n    OF = [(9/5) x OC] + 32OF

n     Rearranging, (OF - 32OF) x (5/9) =  OC



n    volume = length3

n    Metric unit was the  Litre (L)

n   Also spelled liter

n   still commonly used for volume

n    Metric unit = dm3

n    mL - 0.001 L

n    mL = cm3

Units of Measurement

n    Density - mass/volume

n    Density D/N mean weight!!!

n    Specific gravity

n   Density of a substance / density of water

n   Equal to the density in g/mL

n    Calculations

n   Interconvert between mass and volume using the value for density

n    Intensive & Extensive properties

Problems 17 -29 odd

Uncertainty in Measurements

n     Exact numbers - no uncertainty

n    numbers 'by definition’

n    Integers

n    ‘Counting numbers’

n     Measurement - inexact numbers - ALWAYS

n     Precision and accuracy

n    NOT the same thing!

n    I don’t care what Webster says!!

Precision and Accuracy

n    Precision - comparison of values to each other

n    Accuracy - comparison of values to a TRUE value

n    Significant figures

n    use to indicate first uncertain digit

n    non-zero digits are significant

Significant Figures

n     Zero

n    Between s.f.- significant (108)

n    Right of decimal  AND right of s.f. - significant (10.0)

n    left of first s.f. ARE NOT significant. (0.0153)

n    Left decimal and right s.f. - maybe

n     1,000,000,000

n    5 significant figures

n    Because I said so!

Significant Figures

n    Use scientific notation to clear up ambiguity

n    X.YYY x 10Z

n   X = 1-9, Y=0-9

n   Z - any integer

Significant Figures in Calculations

n    Multiplication and Division

n    fewest number of significant figures in the calculation

n    Addition and Subtraction

n    ‘least significant’ decimal place

n    Numbers may contain too many significant figures after manipulation

n    How do we fix this?


n    Used to make answer display the correct number of significant figures

n    Decision from first non-retained digit

n    0-4  round down (108.4 = 108)

n    6-9  round up (107.7 = 108)

n    What about 5


n    non-terminal - round up

n    107.513 = 108

n    terminal - round to the even

n    107.5 = 108

n    108.5= 108

n    Round at the end of a calculation, not in the middle!

Problems 31 - 37 odd

Dimensional Analysis

n    Conversion factors - equal to 1 (no units)

n    can use several sequentially

n    can use to cancel in numerator or denominator


n   Unit conversions

n   Density problems

Problems 39-49 odd

Learning Goals

n    Differentiate among the three states of matter.

n    Distinguish between physical and chemical properties, as well as physical and chemical changes.

n    Distinguish among elements, compounds, and mixtures.

n    Give the symbol for the elements in Table 1.2

n    List the basic SI units, the common metric prefixes and their meanings.

n    Convert temperature among OF, OC, and K.

n    Perform calculations involving density.

n    Determine the number of significant figures in a measured quantity.

n    Express the result of a calculation with the proper number of significant figures.

n    Interconvert metric and English system measurements using dimensional analysis.