Dr.

Currys Life
Mississippi
Place of birth

University of Alabama
Analytical Chemistry, Ph.D.

Military Tour
NAVY

University of West Alabama

Bachelor of Science

CHEMISTRY
The Central Science
10th Edition

Chapter 1
Introduction: Matter &
Measurement

Why Study Chemistry

Chemistry is the study of the properties of materials and
the changes that materials undergo.
Chemistry is central to our understanding of other
sciences.
Chemistry is also encountered in everyday life.

Chemistry: Catastrophe Prevention?

The space shuttle Columbia disintegrated in 2003 upon reentry into

the Earths atmosphere due to a damaged thermal protection system.

The Study of Chemistry

The Molecular Perspective of Chemistry

Matter is the physical material of the universe.
Matter is made up of relatively few elements.
On the microscopic level, matter consists of atoms and
molecules.
Atoms combine to form molecules.
As we see, molecules may consist of the same type of
atoms or different types of atoms.

Molecular Perspective of Chemistry

Classification of Matter

States of Matter
Matter can be a gas, a liquid, or a solid.
These are the three states of matter.
Gases take the shape and volume of their container.
Gases can be compressed to form liquids.
Liquids take the shape of their container, but they do
have their own volume.
Solids are rigid and have a definite shape and volume.

Classification of Matter
Pure Substances and Mixtures
Elements consist of a unique type of atom.
Molecules can consist of more than one type of element.
Molecules that have only one type of atom (an element).
Molecules that have more than one type of atom (a compound).

If more than one atom, element, or compound are found

together, then the substance is a mixture.

 Pure
Substances
and Mixtures

Classification of Matter

Pure Substances and Mixtures

If matter is not uniform throughout, then it is a
heterogeneous mixture.
If matter is uniform throughout, it is homogeneous.
If homogeneous matter can be separated by physical
means, then the matter is a mixture.
If homogeneous matter cannot be separated by physical
means, then the matter is a pure substance.
If a pure substance can be decomposed into something
else, then the substance is a compound.

Classification of Matter

Elements
If a pure substance cannot be decomposed into
something else, then the substance is an element.
There are 114 elements known.
Each element is given a unique chemical symbol (one or
two letters).
Elements are building blocks of matter.
The earths crust consists of 5 main elements.
The human body consists mostly of 3 main elements.

Classification of Matter
Elements

Classification of Matter
Elements
Chemical symbols with one letter have that letter
capitalized (e.g., H, B, C, N, etc.)
Chemical symbols with two letters have only the first
letter capitalized (e.g., He, Be).

Classification of Matter
Compounds
Most elements interact to form compounds.
Example, H2O
The proportions of elements in compounds are the same
irrespective of how the compound was formed.
Law of Constant Composition (or Law of Definite
Proportions):
The composition of a pure compound is always the
same.

Classification of Matter
Compounds
If water is decomposed, then there will always be twice
as much hydrogen gas formed as oxygen gas.
Pure substances that cannot be decomposed are elements.

Classification of Matter
Mixtures
Heterogeneous mixtures are not uniform throughout.
Homogeneous mixtures are uniform throughout.
Homogeneous mixtures are called solutions.

Properties of Matter
Physical vs. Chemical Properties
Physical properties can be measure without changing the
basic identity of the substance (e.g., color, density, odor,
melting point)
Chemical properties describe how substances react or change
to form different substances (e.g., hydrogen burns in oxygen)
Intensive physical properties do not depend on how much of
the substance is present.
Examples: density, temperature, and melting point.

Extensive physical properties depend on the amount of

substance present.
Examples: mass, volume, pressure.

Properties of Matter
Physical and Chemical Changes
When a substance undergoes a physical change, its
physical appearance changes.
Ice melts: a solid is converted into a liquid.

Physical changes do not result in a change of

composition.
When a substance changes its composition, it undergoes a
chemical change:
When pure hydrogen and pure oxygen react completely, they
form pure water. In the flask containing water, there is no
oxygen or hydrogen left over.

Properties of Matter
Physical and Chemical Changes

Properties of Matter
Separation of Mixtures
Mixtures can be separated if their physical properties are
different.
Solids can be separated from liquids by means of
filtration.
The solid is collected in filter paper, and the solution,
called the filtrate, passes through the filter paper and is
collected in a flask.

Properties of Matter

Separation of Mixtures
Homogeneous liquid mixtures can be separated by
distillation.
Distillation requires the different liquids to have different
boiling points.
In essence, each component of the mixture is boiled and
collected.
The lowest boiling fraction is collected first.

Separation of Mixtures

Units of Measurement

Separation of Mixtures
Chromatography can be used to separate mixtures that
have different abilities to adhere to solid surfaces.
The greater the affinity the component has for the
surface (paper) the slower it moves.
The greater affinity the component has for the liquid, the
faster it moves.
Chromatography can be used to separate the different
colors of inks in a pen.

Units of Measurement
SI Units
There are two types of units:
fundamental (or base) units;
derived units.

There are 7 base units in the SI system.

Units of Measurement
Base SI Units

Units of Measurement
SI Units
Selected Prefixes used in SI System

Class Practice Examples

What is the name given to the unit that equals (a)
10-9 grams; (b) 10-6 second; (c) 10-3 meter
What fraction of a meter is a nanometer?

Units of Measurement
SI Units
Note the SI unit for length is the meter (m) whereas the SI unit for
mass is the kilogram (kg).
1 kg weighs 2.2046 lb.

Temperature
There are three temperature scales:
Kelvin Scale

Used in science.
Same temperature increment as Celsius scale.
Lowest temperature possible (absolute zero) is zero Kelvin.
Absolute zero: 0 K = 273.15 oC.

Units of Measurement
Temperature
Celsius Scale
Also used in science.
Water freezes at 0 oC and boils at 100 oC.
To convert: K = oC + 273.15.

Fahrenheit Scale
Not generally used in science.
Water freezes at 32 oF and boils at 212 oF.
To convert:

5
C F - 32
9

9
F C 32
5

Class Practice Example

Make the following temperature conversions:
(a) 68 oF to oC; (b) -36.7 oC to oF

5
C F - 32
9

9
F C 32
5

Units of Measurement
Temperature

Units of Measurement
Derived Units
Derived units are obtained from the 7 base SI units.
Example:

units of distance
Units of velocity
units of time
meters

seconds
m/s

Units of Measurement
Volume

The units for volume are

given by (units of
length)3.
SI unit for volume is 1
m3.

We usually use 1 mL = 1
cm3.
Other volume units:
1 L = 1 dm3 = 1000 cm3 =
1000 mL.

Units of Measurement
Volume

Units of Measurement
Density
Used to characterize substances.
Defined as mass divided by volume:
mass
Density
volume
Units: g/cm3.
Originally based on mass (the density was defined as the
mass of 1.00 g of pure water).

Class Practice Examples

Answer the following problems:
(a) Calculate the density of mercury if 1.0 x 102 g
occupies a volume of 7.36 cm3.
(b) Using the density for mercury, calculate the
mass of 65.0 cm3 of mercury.

Uncertainty in Measurement
All scientific measures are subject to error.
These errors are reflected in the number of figures reported
for the measurement.
These errors are also reflected in the observation that two
successive measures of the same quantity are different.
Precision and Accuracy
Measurements that are close to the correct value are
accurate.
Measurements that are close to each other are precise.

Precision and Accuracy

Uncertainty in Measurement
Significant Figures
The number of digits reported in a measurement reflect the
accuracy of the measurement and the precision of the
measuring device.
All the figures known with certainty plus one extra figure
are called significant figures.
In any calculation, the results are reported to the fewest
significant figures (for multiplication and division) or
fewest decimal places (addition and subtraction).

Uncertainty in Measurement

Significant Figures
Non-zero numbers are always significant.
Zeros between non-zero numbers are always significant.
Zeros before the first non-zero digit are not significant.
(Example: 0.0003 has one significant figure.)
Zeros at the end of the number after a decimal place are
significant.
Zeros at the end of a number before a decimal place are
ambiguous (e.g. 10,300 g).

Dimensional Analysis
Method of calculation utilizing a knowledge of units.
Given units can be multiplied or divided to give the
desired units.
Conversion factors are used to manipulate units:
Desired unit = given unit (conversion factor)
The conversion factors are simple ratios:

desired unit
Conversion factor
given unit

Dimensional Analysis
Using Two or More Conversion Factors
Example to convert length in meters to length in inches:
Number of in number of m conversion m cm
conversion cm in
100 cm
1 in
Number of in number of m

m
2.54 cm

Class Practice Problem

A persons height is measured to be 67.50 in. What is
this height in centimeters?
Perform the following conversions: (a) 2 days to s; (b)
20 Kg to g.

Dimensional Analysis

Using Two or More Conversion Factors

In dimensional analysis always ask three questions:
What data are we given?
What quantity do we need?
What conversion factors are available to take us from
what we are given to what we need?