Transcript Document 7514036
Introduction to Chemistry
Study of the
_________________
of matter and the
_________________
matter undergoes.
1. Organic chemistry 2. Inorganic chemistry 3. Analytical chemistry 4. Physical chemistry 5. Biochemistry -
Understanding Concepts
Chemistry deals with scientific facts facts that can be discovered by making observations and doing experiments.
It is often necessary to rely on information that others have discovered.
Diamond
Hardest known substance.
A form of the element carbon.
Highly ordered molecular structure.
Not the most stable form of carbon.
Macro vs. Micro
_________________ - things you see with the unaided eye or large scale experimenting.
_________________ - things too small to see with the unaided eye or small scale experimenting.
Matter and Change
Matter
Anything that has _________________ _________________ .
and takes up Everything is made up of matter.
Definitions for Components of Matter
_________________
-
the simplest type of substance with unique physical and chemical properties.
An element consists of only one type of atom.
It cannot be broken down into any simpler substances by physical or chemical means.
_________________
-
a structure that consists of two or more atoms that are chemically bound together and thus behaves as an independent unit.
Definitions for Components of Matter
_________________
-
a substance composed of two or more elements which are chemically combined.
_________________
-
a group of two or more elements and/or compounds that are physically intermingled.
_________________ - amount of matter the object contains - measured in grams.
_________________ - matter that has uniform and definite composition (pure substances) - contain only one kind of matter.
Physical Properties
Quality or condition of a substance that can be observed or measured without changing the substance’s composition.
Color odor hardness density melting & boiling points solubility
Physical properties help chemists _________________ substances.
Physical Change
Matter can be changed in many ways without changing the chemical composition of the material.
Cutting • Dissolving • Crack Grinding Boiling Bending • Melting • Crush • Freezing • Break Tearing • Condensing
Melting or Freezing of Water
Melting ice into liquid is a physical change, along with changing liquid to steam and steam to condensation.
There is no alteration to the chemical composition of water, only a change of state.
Chemical Property
The ability of a substance to undergo a chemical reaction and to form new substances.
Chemical properties are only observed when a substance undergoes a chemical change.
A chemical change always results in a change in the chemical composition of the substances involved.
Burning Decompose Rust Explode Corrode Rot
Physical Properties
those which the substance shows by itself without interacting with another substance such as color, melting point, boiling point, density
Chemical Properties
those which the substance shows as it interacts with, or transforms into, other substances such as flammability, corrosiveness
Figure 1.1
The distinction between physical and chemical change.
A Physical change B Chemical change
Sample Problem 1.1
Distinguishing Between Physical and Chemical Change PROBLEM:
Decide whether each of the following process is primarily a physical or a chemical change, and explain briefly: (a) Frost forms as the temperature drops on a humid winter night.
(b) A cornstalk grows from a seed that is watered and fertilized.
(c) Dynamite explodes to form a mixture of gases.
(d) Perspiration evaporates when you relax after jogging.
(e) A silver fork tarnishes slowly in air.
States of Matter
States of Matter
_________________
- definite shape and volume.
Particles are packed tightly together.
Almost incompressible.
Expand only slightly when heated.
_________________
- indefinite shape and definite volume.
In close contact with one another.
Liquids can flow.
Almost incompressible.
Tend to expand when heated.
Gas - indefinite shape and volume.
Gas particles are far apart.
Easily compressed.
Expand without limit to fill any space.
_________________ - describes the gaseous state of a substance that is generally a liquid or solid at room temperature (different than a gas).
Classifying Mixtures
Physical blend of two or more substances.
Compositions may vary.
Heterogeneous Mixture
Not uniform in composition.
If you were to separate the mixture into portions, each portion would be different from the other.
Homogeneous Mixture
Completely uniform throughout.
Components are evenly distributed throughout.
Separate the mixture into portions and the portions would be the same.
Also called _________________ - may be gases, liquids, or solids.
Scientific Method
An important scientific discovery may involve some luck, but one must be prepared to recognize the lucky event.
Alexander Fleming Most advances in science involves little or no luck, but a logical systematic approach to the solution of a difficult problem.
Scientific Method
Logical approach to the solution of scientific problem.
Related to ordinary common sense.
Observation
Using your senses to obtain information directly.
Hypothesis
A possible
_________________ _________________
for what is or observed.
A proposal
Experiment
Test the hypothesis.
For the results of an experiment to be accepted, the experiment must produce the same result no matter how many times it is repeated, or by whom.
If the experimenting does not support the hypothesis, the hypothesis must be changed.
The process of testing the hypothesis must be carried out until the hypothesis fits all the observed experimental facts.
Theory
Once a scientific hypothesis meets the test of repeated experimentation, it may become a theory.
A theory is a broad and extensively tested explanation of why experiments give certain results.
A theory can never be proved because it is always possible that a new experiment will disprove it.
Theories give you the power to predict the behavior of natural systems.
Scientific Law
Concise statement that summarizes the results of many observations and experiments.
Describes a natural phenomenon without attempting to explain it.
Can be expressed as a mathematical equation.
A
_________________
states what happens; a
_________________
explains why.
International System of Units
The Metric System
Metric System
The metric system was developed in France in the 1790s.
The metric system missed being nationalized in this country by one vote in the late 1700s.
Metric System
Based on the powers of 10.
Countries that have not officially adopted the Metric System include: United States Liberia, Africa Berma, Southeast Asia
Why should we use the metric system?
We are living in a metric world where just about every country, except the USA, uses the metric system, and other countries are now telling us that they don't want to buy some of the products manufactured by U.S. companies if they aren't made to metric sizes (and if they aren't labeled in metric units).
Many European Union (EU) countries, which have been good customers of U.S. companies, don't allow products into their countries unless they are made to metric system standards. We must operate in the world marketplace, and we can't stay competitive if we don't provide metric goods.
In addition, beginning on January 1, 2010, the EU will require products to be labeled solely in metric measurements. If US laws are changed to allow metric only labeling, it will be easier for US companies to comply with that directive.
With 99% of the rest of the world using metric, there is no chance we can persuade them to use our inches and pounds.
Metric System
Based on the powers of 10 milli centi deci (basic unit) deca hecta kilo-
Between each step, there is an increase by a power of 10.
10 mm = 1 cm 10 cm = 1 dm 10 dm = 1 m 10 m = 1 dam 10 Dm = 1 hm 10 Hm = 1 km
Yotta Zetta Exa Peta Tera Giga Mega Kilo Basic Unit Milli Micro Nano Pico Femto Atto Zepto Yocto f p a z m
n y Y Z E P T G M k 10 24 10 21 10 18 10 15 10 12 10 9 10 6 10 3 1 10 -3 10 -6 10 -9 10 -12 10 -15 10 -18 10 -21 10 -24
As you move from a small to large, you move the decimal that many places to the left.
As you move from large to small, you move the decimal that many places to the right.
Units of Length
SI unit = meter (m) 1 meter = 1000 mm 1 meter = 1.09 yards = 39.36 inches 1 km = 1000 meters 1 km = 0.62 miles 1 inch = 2.54 cm
Units of Length
Unit used for measuring atoms in chemistry is the Ångström – Å = 10 -8 cm Centimeter is about the diameter of a dime Millimeter is about the thickness of a dime
Units of Volume
_________________ occupied by any sample of matter.
SI unit = m 3 More common unit = liter (L) 1 L = 1000 mL 1 mL = 1 cm 3
Units of Volume
Unit of volume for a solid length x width x height = volume of a regular shaped object (cm 3 ) 1 mL = 1 cm 3 One liter is a little more than a quart One cup is 250 mL
Units of Mass
_________________ - measure of the quantity of matter in an object.
_________________ - force that measures the pull of gravity on any given mass.
SI unit = kilogram (kg) 1 kg = 1000 grams (g) 1 kg = 2.12 pounds One gram is about the mass of a paperclip
Units of Temperature
Kelvin Scale 0 K = -273 C Degree Celsius (°C) 0°C = 32°F (freezing point of water) 100°C = 212°F (boiling point of water)
Conversion between Temperatures
F to C ( C x 1.8) + 32 = F C to F ( F – 32) 1.8 = C
Time
SI Unit = second (s)
Graphing
Graphing
The relationship between two variables in an experiment is often determined by graphing the experimental data.
The graph is a “picture” of the data.
Graphing Information
_________________ Variable manipulated variable X-axis (horizontal) _________________ Variable responding variable Y-axis (vertical)
0 5 10 15 20 25 30 Time (seconds) Distance (meters) 0 3.5
6.2
10.1
17.3
26.5
37.1
Time vs. Distance
40 35 30 25 20 15 10 5 0 0 0 26.5
17.3
10.1
3.5
6.2
10 20
Time (seconds)
30 37.1
40
Scientific Measurement
Types of Measurements
_________________ measurements results are given in descriptive, non-numerical form.
_________________ measurements results are given in definite form, usually as numbers and units.
Scientific Notation
A number written as the product of two numbers: a coefficient and 10 raised to a power.
3.6 x 10 5 The coefficient is always written as a number greater than one and smaller than ten - only one number to the left of the decimal.
Multiplication & Division
In multiplication of scientific notation values, multiply the coefficients and add the exponents.
In division of scientific notation values, divide the coefficients and subtract the exponents.
Addition & Subtraction
Before adding or subtracting, the exponents must be the same.
After the exponents are the same, add or subtract the coefficients with the 10 raised to the power of.
Significant Figures
It is important to be honest when reporting a measurement, so that it does not appear to be more accurate than the equipment used to make the measurement allows. We can achieve this by controlling the number of digits, or _________________, used to report the measurement.
Rule 1:
All nonzero digits are significant.
Rule 2:
Zeros within a number are always significant. Both 4308 and 40.05 contain four significant figures.
Rule 3:
Zeros that do nothing but set the decimal point are not significant. Thus, 470,000 has two significant figures.
Rule 4:
Trailing zeros that aren't needed to hold the decimal point are significant. For example, 4.00 has three significant figures.
How many sig figs?
(a)
0.0030 L
(b)
0.1044 g
(c)
53,069 mL
(d)
0.00004715 m
(e)
57,600. s
(f)
0.0000007160 cm
3
Rules for Sig Figs in Answers
When combining measurements with different degrees of accuracy and precision, the accuracy of the final answer can be no greater than the least accurate measurement.
This principle can be translated into a simple rule for addition and subtraction:
When measurements are added or subtracted, the answer can contain no more decimal places than the least accurate measurement.
Addition & Subtraction
Example: adding two volumes 83.
5 mL + 23.28 mL 106.78 mL =
106.8
mL Example: subtracting two volumes 865.
9 mL 2.8121 mL 863.0879 mL =
863.1
mL
Rules for Sig Figs in Answers
The same principle governs the use of significant figures in multiplication and division: the final result can be no more accurate than the least accurate measurement.
In this case, however, we count the significant figures in each measurement, not the number of decimal places:
When measurements are multiplied or divided, the answer can contain no more significant figures than the least accurate measurement.
Multiplication & Division
9.2 cm x 6.8 cm x 0.3744 cm = 23.4225 cm 3 = 23 cm 3
Rounding
When the answer to a calculation contains too many significant figures, it must be rounded off.
Rounding
If the digit is smaller than 5, drop this digit and leave the remaining number unchanged. Thus, 1.684 becomes 1.68. If the digit is 5 or larger, drop this digit and add 1 to the preceding digit. Thus, 1.247 becomes 1.25.
Uncertainty in Measurements
_________________ - measure of how close a measurement comes to the actual or true value of whatever is measured.
_________________ - measure of how close a series of measurements are to one another. (depends on multiple measurements)
precise but not accurate precise and accurate