(c)2007 prentice hall1 the chemistry of everything kimberley waldron chapter 1 everything an...

(C)2007 Prentice Hall 1

The Chemistry of EverythingKimberley Waldron

Chapter 1 EverythingAn overview of the composition of

matter and the way scientists study it

Richard Jarman, College of DuPage


Chapter Topics

• The periodic table, classes of subatomic particles, electron density.

• Elements, compounds, molecules, chemical reactions, balanced chemical equations.

• Separation of substances in a mixture, homogeneous and heterogeneous mixtures.

• Sizes of atoms, SI units, conversion factors, dimensional analysis.

• Common units of measure, measurement of temperature • The scientific method, testing hypotheses, scientific

models.


Science and Change

• The twentieth century saw a revolution in technological advances:– Automobiles– Electricity– Computers

• Everything has gotten much faster, even if we think things are still slow.


Technical Advance Builds on Discovery

• Technical advances do not just happen.

• They depend on scientific discovery.

• 19th century was one of discovery:– Electrons– X-rays– Radioactivity


Changing Our Views of Matter

• X-rays and radioactivity changed ideas about atoms.

• Atoms can absorb and emit radiation.

• X-rays gave us pictures of molecules.


Radiation for Good and Evil

• X-rays gave insights into the nature of penicillin and DNA.

• Radioactivity provided the means to split atoms and destroy the world.


DNA

• X-rays provided a picture of the structure of DNA.

• The DNA double helix explains transfer of genetic information.

• We can modify the helix by genetic engineering.


For Good and Evil

• Science has been used for great good…

• …and great evil.• What is good for some is

not always good for others.

• Arguments for or against are often complex.

• Science education helps us make informed decisions.


Atoms – The Basis of Matter

• An atom is the smallest unit of matter.

• All matter is made of atoms.

• There are different types of atoms.

• Each type is an element.


Elements and the Periodic Table

• The elements (about 114) are arranged in the periodic table.

• Each row is a period.• Each column is a group.


Atomic Structure

• Atoms contain nuclei.• The nucleus contains

protons and neutrons.

• The nucleus is very dense and very tiny.


Atomic Facts and Figures

• Atomic number: All atoms of the same element contain the same number of protons.

• Each element has a unique atomic number.

• Neutral atoms contain same number of electrons and protons.

• Electrons live outside the nucleus.


Particles, Clouds and the Illusive Electron

• Electrons were thought to be particles orbiting the nucleus like moons around a planet.

• The modern view is that they are “clouds” smeared out in space.


Chemical Reactions

• Any chemical reaction involves electrons.

• Electrons are given, taken away or shared.

• Chemical reactions involve compounds – the combination of atoms.


Elements and Compounds

• Elements contain only one type of atom:– Neon, Gold, Fluorine

• Compounds contain more than one type of atom in simple fixed ratios:– Carbon dioxide, water


Molecules and Bonds

• Molecules are the basic blocks of substances.

• Molecules contain atoms bonded together.

• Chemical bond is the interaction of electrons to join atoms together.

• Without bonds all matter would be a gas.


Big Bang Theory

• Nitroglycerin is a molecule.

• It is unstable – decomposition of nitroglycerin produces an explosion.

• Dynamite (invented by Alfred Nobel) is a mixture of nitroglycerin with chalky material to make it more stable.


Describing Reactions

• Chemical equations are ways to describe what happens in a chemical reaction.

• Symbols are used for the substances.

• Reactants are the starting materials.

• Products are obtained in the reaction.

• Arrows show the direction.

Reactants Products


Anatomizing the Reaction

• Existing chemical bonds are broken.

• New chemical bonds are made.

• The number of atoms remains the same.

• They just change places.


The Chemical Formula

• Subscripts tell us how many atoms of each element are in the molecule.

• Each molecule of TNT contains:– 7 atoms of carbon– 5 atoms of hydrogen– 3 atoms of nitrogen– 6 atoms of oxygen

7 5 3 6C H N O


Keeping in Balance3 5 3 9 2 2 2 24 ( ) 6 ( ) 10 ( ) ( ) 12 ( )C H N O l N g H O g O g CO g

Reactants Products4C3H5N3O9 6N2 10H2O O2 12CO2

C 4 x 3 = 12 12 x 1 = 12

H 4 x 5 = 20 10 x 2 = 20

N 4 x 3 = 12 6 x 2 = 12

O 4 x 9 = 36 10 x 1 = 10 1 x 2 = 2 12 x 2 = 24


Models and Molecules: Visualizing the Unseen

• We use models to show the atoms in molecules – balls and sticks.

• Computers use molecular models to design new drugs.


Clean or Pure?

• A pure substance is one that contains only one element or compound.

• Something that is “clean’ is probably not strictly pure – a mountain stream contains salt.


Mixtures are Impure

• Nature tends to mix things – more than one pure substance mixed together.

• Homogeneous mixture is uniform on a molecular level (a solution).

• Heterogeneous mixture is non-uniform – a bottle of Dulcolax.


AN ALYSIS O F MAT T ER

HOM OGENEOUS M IXT UREsa ltw a te r, ru b b in g a lcoh o l

COM POUNDw ater

ELEM ENTcarbon

Can it be decom posed in tosim p ler substances using

chem ical m ethods?

PURE S UBST A NC E

Can it be separatedby physical m ethods?

HOM OGENEOUS M IXT URE HET EROGENEOUS M IXTUREb lood , so il

Is it un ifo rm ?

M ATTER

YESYES

YESYES

YESYES NONO

NONO

NONO


Let’s Get Physical

• Components of a mixture can be separated (purified) by physical means.

• Physical is altering a substance without any changes to the chemical composition.

• A saline solution (mixture) is still salt and water.

• Water can be removed by evaporation.


Chemical Changes

• Chemical change involves breaking down a substance into other substances.

• Boiling (physical) converts water into steam.

• Electrolysis (chemical) converts water into hydrogen and oxygen – new substances:

2 2 22 ( ) 2 ( ) ( )ElectricityH O l H g O g


All Matter is Ultimately Made from Elements


Questions of Science

• Scientific discoveries create complex questions:– Discovery of the atom led to potential for source of

power combined with radioactive waste.

• Should scientists be free to pursue any research?

• Should government control scientific progress?• What is the progression of science?

– Research normally follows a logical progression.– Interest focuses on problems that impact humanity.


The Importance of Publication

• Results of chemical research are submitted for publication.

• Publication involves peer review by other scientists.

• Publication and peer review establish the legitimacy of scientific progress.


What is Science?

• Science conforms to rules and conventions.

• Without rules it is meaningless.• Hypothesis is the basis of the scientific

method.• A proposal about how something behaves

which is testable by observation.• Hypotheses that cannot be tested are not

scientific (the supernatural).

(C)2007 Prentice Hall

SCIENTIFIC METHODSCIENTIFIC METHOD1. 1. FACT :FACT : An observable event; indisputable evidence which does An observable event; indisputable evidence which does not explain but simply is.not explain but simply is.

2. 2. HYPOTHESIS:HYPOTHESIS: A guess to try to explain an observation. A guess to try to explain an observation.

3. 3. EXPERIMENT:EXPERIMENT: A systematic exploration of an observation or A systematic exploration of an observation or concept.concept.

4. 4. THEORY:THEORY: An explanation of the facts; it can be proven by An explanation of the facts; it can be proven by experiment and it confirms an hypothesis.experiment and it confirms an hypothesis.

5. 5. LAW:LAW: A theory which has undergone rigorous experimentation and A theory which has undergone rigorous experimentation and no contradiction can be found.no contradiction can be found.

Note:Note: MODEL:MODEL: A visual or mathematical device or method used to A visual or mathematical device or method used to demonstrate a theory or concept.demonstrate a theory or concept.


Theory and the Method

• A theory is an explanation of the observed phenomenon using experimental data.


Which Side is Your Bread Buttered?

• Scientific hypothesis must be subject to experimental test.Hypothesis: The buttered side of bread always lands face down on the floor.

• Test by dropping bread on the floor many times.


Results and Theories

• Buttered side lands face down 90 % of the time.

• Formulate a theory: the height of the table determines what side the bread lands.

• Experiments test a theory but never prove it.

• The next experiments may falsify it.


Numbers and Units in Science

• Scientists measure very large numbers: – 160,000,000,000,000,

000,000,000 atoms in a coin.

• And very small numbers:– The diameter of the

atom is 0.000 000 000 153 meter.


MEASUREMENTSMEASUREMENTSScientific NotationScientific Notation

Many measurements in science involve either very large numbers or very small numbers (#). Scientific notation

is one method for communicating these types of numbers with minimal writing.

GENERIC FORMAT:GENERIC FORMAT: # . # #… x 10 # . # #… x 10##

A negative exponent represents a number less than 1 and a positive exponent represents a number greater

than 1.

6.75 x 10-3 is the same as 0.00675

6.75 x 103 is the same as 6750


MEASUREMENTSMEASUREMENTSScientific NotationScientific Notation

Give the following in scientific notation (or write it out) with the appropriate significant figures.

1. 528900300000 =

2. 0.000000000003400 =

3. 0.23 =

4. 5.678 x 10-7 =

5. 9.8 x 104 =

5.289003 x 1011

3.400 x 10-12

2.3 x 10-1

0.0000005678

98000


GROUP STUDY PROBLEM #1GROUP STUDY PROBLEM #1

Show all work for the following questions on the back page. Always give the correct significant figures.

1. What is the scientific method?

2. Explain why tasting chemicals during an experiment is not a safe practice?

3. Express each of the following numbers in scientific notation.

a) 0.0404 _______ b) 0.0081 _______

c) 40.0 _______ d) 2900000 _______

e) 0.0000055 _______ f) 40300 _______

4. (452 x 6.2) / 14.30 = ______________________

5. 98.78564 - 97.9299 = ________________

6. 6.022 x 1023 / 1.9 x 10-19 = ________________

7. ( 0.3 - 0.09) / (4.3 x 10-3 + 7.232 x 10-4) = ____________

8. [(2.4 x 1012) (5.78 x 10-31)]3 / (2.965 x 1014)1/2 = __________


MEASUREMENTSMEASUREMENTSSSignificant ignificant FFiguresigures

1. All nonzero numbers are significant figures.

2. Zero’s follow the rules below.

Zero’s between numbers are significant.

30.09 has 4 SF

Zero’s that precede are NOT significant.

0.000034 has 2 SF

Zero’s at the end of decimals are significant.

0.00900 has 3 SF

Zero’s at the end without decimals are ambiguous.

4050 has either 4 SF or 3 SF


MEASUREMENTSMEASUREMENTSSSignificant ignificant FFigures & Calculationsigures & Calculations

Adding/subtracting

345.678 0.07283

+ 12.67 -0.0162789

Multiplying/dividing

12.0340 x 3.98 =

98.657 / 43 =

358.35 0.05655

47.9

2.3


Metric System – a Unit for All Occasions

• Systeme Internationale (SI) is standard units for science.• Prefixes adjust the scale to suit the object:

– 1 m = .001 km– 1 m = 1,000 mm– 1 m = 1,000,000,000 nm

• System is based on powers of ten for easy use.


MEASUREMENTSMEASUREMENTS There are different types of measurements that can be

made in the laboratory like mass, time, volume, and length.

These measurements can be made using either the metric system or the English system. The metric system is based on increments of 10.

1 base = 100 centibases “c” = centi

1 base = 1000 millibases “m” = milli 1 kbase = 1000 bases

1 base = 106 microbases “” = micro k = kilo

1 base = 109 nanobases “n” = nano

The first step to understanding measurements is to learn the types, symbols, & units associated with these measurements.


The Base Units

• The most important and frequently used units in chemistry:


MEASUREMENTSMEASUREMENTS

• There are different types of measurements that can be made in the lab for length, mass, volume, temperature, area, time, heat and pressure.

Unit Metric English

Length Meter (m) Inches (in) or Feet (ft)

Mass Gram (g) Pounds (lb)

Volume Liters (L) Gallon (gal)

Temperature Celsius (°C) and Kelvin (K)

Fahrenheit (°F)

Area Square meters (m2)

Square feet (ft2)

Time Seconds (s) Minutes (min) or Hours (hr)

Heat Calories (cal) or Joules (J)

British Thermal Units (BTU)

Pressure Atmospheres (atm), Torr, or mmHg

Pounds/sq in (lb/in2)


Using Conversion Factors

1 m = 1,000 mm

• Divide one number by the other and we have a conversion factor.

1 1,0001

1,000 1

m mm

mm m


The sizes of atoms

• Atoms are measured in picometers:1,000,000,000,000 pm = 1m

• Convert picometers to meters

• Rationale for using prefixes: size of a Kr atom is 110 pm:

1 1,000,000,000,000

1,000,000,000,000 1

m pmor

pm m

1110 0.000000000110

1,000,000,000,000

mpmx m

pm


Importance of Dimensional Analysis

• Height of each letter = 0.000 000 000 00130 km

• Radius one atom =

• Convert to m

• Convert to pm

• Atoms in figure are Xe

10000.000000000000130 0.000000000130

1

mkmx m

km

1000 1

1 1000

m kmor

km m

0.000000000001300.000000000000130

10

kmkm

10000000000000.0000000000130 130

1

pmmx pm

m


MEASUREMENTSMEASUREMENTS Since two different measuring systems exist, a scientist must be

able to convert from one system to the other.

CONVERSIONSCONVERSIONSLength 1 in = 2.54 cm

1 mi = 1.61 km

Mass 1 lb.... = 454 g

1 kg = 2.2 lb....

Volume 1 qt = 946 mL

1 L = 1.057 qt

4 qt = 1 gal

1 mL = 1 cm3


Units of Volume

• Standard metric unit for volume in chemistry is milliliter mL.

• Equivalent in cubic centimeter cm3 or cc.

1 mL = 1 cm3 = 1 cc• Other volume units are

nanoliter (nL), picoliter (pL) and femtoliter (fL).


Some Like it Hot: Temperature Measurement in Science

• Temperature is related to molecular motion.

• As motion decreases, T decreases.

• At absolute zero all motion ceases.

• SI unit for temperature is Kelvin.

• Kelvin scale has absolute zero as zero reference point 0 K.


Celsius, Fahrenheit and Kelvin

• Converting between Celsius and Kelvin:– Moving the reference

K = ºC + 273.15

ºC = K + 273.15• Converting between

Celsius and Fahrenheit:– Move the reference and

change the scale

ºC = 5/9(ºF – 32)

ºF = 9/5(ºC) + 32


GROUP STUDY PROBLEM #2GROUP STUDY PROBLEM #2

_____1. Water boils at 212 oF, what is the boiling point of water in oC and in Kelvin?_____2. Convert 25.0 mm to m_____3. Convert 25.0 g to cg_____4. Convert 25.0 kJ to cal_____5. Convert 25.0 lb to mg _____6. Convert 25.0 gal to L_____7. How many liters of gasoline will be used to drive 725 miles in a car that averages 27.8 miles per gallon?_____8. Calculate the volume, in liters, of a box that is 5.0 cm long by 5.0 inches wide by 5.0 mm high.


Introduction to Density Density is the measurement of the mass of an object per

unit volume of that object.

d = m / V Density is usually measured in g/mL or g/cm3 for solids or

liquids.

Volume may be measured in the lab using a graduated cylinder or calculated using:

Volume = length x width x height if a box or V = r2h if a cylinder.

Remember 1 mL = 1 cm3


Practice Problems on density ___________ 1. Calculate the volume, in microliters, of

a cylinder that is 32.42 mm long with a diameter of 0.0789 cm.

• ___________ 2. Calculate the density of a solution if 45.0 mL of the solution weighs 7.12 x 10-2 kg.

• ___________ 3. The Hope diamond weighs 45.52 carats and has a density of 3.51 g/cm3. What is the volume of this diamond? (1 carat = 200 mg)

• ___________ 4. A plastic material weighing 2.2 lb is shaped into a cylinder 13.5 cm in height and 6.8 cm in diameter. Will this object sink or float in water?

• ___________ 5. A student fills a 50.0 mL graduated cylinder with 25.0 mL of water, then places a spherical object weighing 54.367 g into the graduated cylinder. The new volume is 41.5 mL. Calculate the density of the object.

3.29 g/mL

2.59 cm3

2.0 g/cm3; sink

1.58 g/mL

15.9 L

(c)2007 prentice hall1 the chemistry of everything kimberley waldron chapter 1 everything an...

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