Chemistry: Stuff & measuring it

1. Chemistry
• the study of matter
• its chemical and physical properties
• the chemical and physical changes it undergoes
• the energy changes that accompany those
processes
• Most changes either require energy or
produce energy
• This class will focus on the changes that
happen in living systems

2. Why do you need to know
chemistry?
public health pharmaceutical industry
CHEMISTRY
food science
medical practitioners
forensic sciences

3. Chemistry overlaps with many different disciplines.
+
Bunny reproduction is biology!

4. Chemistry overlaps with many different disciplines.
But chemists study the
hormonal changes that tell the
bunnies when to mate!
+
Bunny reproduction is biology!

5. Chemistry overlaps with many different disciplines.
Psychologists study how mice “learn”.

6. Chemistry overlaps with many different disciplines.
But chemists study the
neurotransmitters responsible
for learning!
Psychologists study how mice “learn”.

7. Chemistry overlaps with many different disciplines.
What happens when a bunny
baby crosses a road is physics.

8. Chemistry overlaps with many different disciplines.
What happens when a bunny
baby crosses a road is physics.

9. Chemistry overlaps with many different disciplines.
What happens to the bunny baby‟s body
in the hot summer sun is chemistry!

10. MAJOR AREAS OF CHEMISTRY
• Biochemistry - the study of life at the
molecular level
• Organic chemistry - the study of matter
containing carbon and hydrogen
• Inorganic chemistry - the study of matter
containing elements, not organic
• Analytic chemistry - analyze matter to
determine identity and composition
• Physical chemistry - attempts to explain the
way matter behaves

11. Chemistry uses the scientific method
• How does something
work?
• What is the “truth”
about how something
works?
• Does my data support
my hypothesis?
• Do I need to change my
hypothesis?

12. Experimental methods
• Experiments produce DATA & RESULTS
• DATA:
– Recorded observations or measurements
• Mass, Time, Temp, volume, energy
• RESULTS:
– Outcome of experiment
– Conclusions drawn from observations
– Usually several pieces of data form a result

13. CHEMISTRY
the study of matter
and its changes
. . . but what is matter?

14. CHEMISTRY
the study of matter
and its changes
Matter is “stuff ”
(anything with mass and volume)

15. CHEMISTRY
the study of matter
and its changes
Which of these are matter?
hammer Q-tip fear paper bag beauty
blood talent acorn air gravity

16. Classification of Matter
• Pure substance - a substance that has only one
component
• Mixture - a combination of two or more pure
substances in which each substance retains its own
identity, not undergoing a chemical reaction

17. Classification of Matter
• Element - a pure substance that cannot be changed
into a simpler form of matter by any chemical reaction
• Compound - a substance resulting from the
combination of two or more elements in a definite,
reproducible way, in a fixed ratio

18. Classification of Matter
• Mixture - a combination of two or more pure substances in
which each substance retains its own identity
• Homogeneous - uniform composition, particles well mixed,
thoroughly intermingled
• Heterogeneous – nonuniform composition, random
placement

19. Classification of Matter
• Which classes of matter are shown below?
Homogeneous Heterogeneous
compound
mixture mixture

20. The Periodic Table of
the Elements

21. The Periodic Table of the Elements
We know that all “matter” is made up of
very, very, very tiny spheres called atoms.
Each square in this table represents a different kind of atom.
There are over 114 different kinds of atoms.

22. The Periodic Table of the Elements
We know that all “matter” is made up of
very, very, very tiny spheres called atoms.
Each square in this table represents a different kind of atom.
Table organization is based on each atom‟s makeup and the
similarities of the properties of the various kinds of atoms.

23. The Periodic Table of the Elements

24. The Periodic Table of the Elements

25. The Periodic Table of the Elements

26. The Periodic Table of the Elements
Table is usually displayed this way.
(it takes up less space)
We won‟t discuss any
of these elements in
Physiological
Chemistry

27. The Periodic Table of the Elements
Every kind of atom has a name and a “symbol.”

28. The Periodic Table of the Elements
All modern symbols are based on letter abbreviations
Hydrogen (H)
Every symbol starts
Oxygen (O)
with a capital letter.
Iodine (I)

29. The Periodic Table of the Elements
Some symbols have two letters.
Scandium (Sc)
First letter is capital
Bismuth (Bi)
and second is lower case.
Neon (Ne)

30. The Periodic Table of the Elements
Some symbols come from foreign languages.
Tungsten (W) -- „W‟ is from wolfram (German)
Sodium (Na) -- „Na‟ is from natrium (Latin)
Antimony (Sb) -- „Sb‟ is from Stibium (Latin)

31. The Periodic Table of the Elements
Some types of atoms are very common in air!
nitrogen, oxygen, carbon, argon, neon, helium

32. The Periodic Table of the Elements
Some types of atoms are very common in dirt and rocks!
oxygen, silicon, aluminum, iron, calcium, sodium

33. The Periodic Table of the Elements
Some types of atoms are very common in stars!
hydrogen, helium, carbon, oxygen, neon, magnesium

34. The Periodic Table of the Elements
Some types of atoms are very common in human bodies!
oxygen, carbon, hydrogen, nitrogen, calcium, phosphorus

35. The Periodic Table of the Elements
18 columns
(Columns are called groups)
1 2 3 4 . . . . . . . . . . . . . . . . . . . . . . . . . 16 17 18

36. The Periodic Table of the Elements
This is group 13.

37. The Periodic Table of the Elements
7 rows
(Rows are called periods)
1
2
3
4
5
6
7

38. The Periodic Table of the Elements
This is period 4.

39. The Periodic Table of the Elements
alkali metals
(Group 1)

40. The Periodic Table of the Elements
alkaline earth metals
(Group 2)

41. The Periodic Table of the Elements
halogens
(Group 17)

42. The Periodic Table of the Elements
noble gases or “inert” gases
(Group 18)
All of the atoms in a group
have similar properties.

43. Consider these three halogens:
http://www.an.psu.edu/rxg1/pt1999/halogens.html

44. Consider these three halogens:
•All smell like a swimming pool.
•All produce colored vapors.
•All are poisonous.
•All react rapidly with sodium to give
edible salts.
Groups in the periodic table are comprised
of elements with similar properties.
http://www.an.psu.edu/rxg1/pt1999/halogens.html

45. Consider these three alkali metals:
Lithium (Li)
Sodium (Na)
Potassium (K)

46. Consider these three alkali metals:
•All are shiny, soft solids when pure.
•All melt at very low temperatures.
Lithium mp = 181oC
Sodium mp = 98oC
Potassium mp = 63oC

47. Consider these three alkali metals:
•All are shiny, soft solids when pure.
•All melt at very low temperatures.
•All react violently with water.
http://www.westga.edu/~chem/courses/desc.inorg/490Jan14/sld009.htm

48. The Periodic Table of the Elements
Metals
Non-metals
Metalloids or semimetals
Hydrogen
is an odd-
ball!

49. The Periodic Table of the Elements
Metals are . . .
•Lustrous •Ductile
•Malleable •Conductors of
•Prone to losing electricity
electrons •Lower Left of periodic
table

50. The Periodic Table of the Elements
Nonmetals are . . .
•Not lustrous •Not ductile
•Not malleable •Not conductors of
•Often prone to gaining electricity
electrons •Upper Right of
table

51. Classification & Behavior of Matter
• Properties of Matter
– Physical
– Chemical
What are some examples of properties of matter?
• States of Matter
– Solid
– Liquid
– Gas
• Gas Laws

52. Chemical Properties & Change
• Property - result in a change in composition
and can be observed only through a chemical
reaction
• Reaction (chemical change) - a process of
rearranging, removing, replacing, or adding
atoms to produce new substances
hydrogen + oxygen  water
reactants products

53. Physical Properties & Change
• Property - is observed without changing the
composition or identity of a substance
• Change - produces a recognizable difference in
the appearance of a substance without
causing any change in its composition or
identity
- conversion from one physical state to another
- melting an ice cube

54. Separation by Physical Properties
Magnetic iron is separated from other nonmagnetic
substances, such as sand. This property is used as a
large-scale process in the recycling industry.

55. Three States of Water
(a) Solid (b) Liquid (c) Gas

56. Three States of Matter
• gas - particles widely separated, no
definite shape or volume solid
• liquid - particles closer together, definite
volume but no definite shape
• solid - particles are very close together,
define shape and definite volume

57. Comparison of states of matter
Solid Liquid Gas
ordered not ordered not ordered
condensed condensed not condensed

58. Solid Properties

59. Solids are . . .
•Not compressible
•Organized
•Don’t take the shape of their container!
But solids are more complex than this!

60. All solids are considered by chemists to
be either crystalline or amorphous.
Crystalline: at the atomic
level, material is highly organized and has a
repeating pattern of particles
Amorphous: at the atomic level, material
appears randomly thrown together and no
patterns are present.

61. All solids are considered by chemists to
be either crystalline or amorphous.
Crystalline: at the atomic
level, material is highly organized and has a
repeating pattern of particles
Ionic Solids
Molecular Solids
Metallic Solids
Covalent Solids

62. Gases
http://www.btinternet.com/~digital.wallpapers/hot_air_balloon.j

63. Some Gaseous Odds and Ends
 Gases have very low densities
N2 (s) d = 1.03 g/mL
N2 (l) d = 0.808 g/mL (78%)
N2 (g) d = 0.00125 g/mL (0.12%)
(implied by “mostly empty space”)

64. Some Gaseous Odds and Ends
 Gases readily expand to fill their container
(implies that gas molecules are moving rapidly)

65. Some Gaseous Odds and Ends
 Gases are readily compressible
(implied by “mostly empty space”)

66. Some Gaseous Odds and Ends
 Gases are readily compressible
(Liquids and solids are already
compressed)

67. Some Gaseous Odds and Ends
 And they “spring” back!
(implies that gases exert “pressure”)

68. Some Gaseous Odds and Ends
Gases exert “pressure” because gas
molecules collide with container.
Usually “pounds” or Newtons
force
Pressure
Area Usually in2 or m2
pounds Newtons
in 2 m2

69. Some Gaseous Odds and Ends
Gases exert “pressure” because gas
molecules collide with container.
usually abbreviated as
“psi”
pounds Newtons
in 2 m2

70. Some Gaseous Odds and Ends
Gases exert “pressure” because gas
molecules collide with container.
known as a “Pascal” (Pa)
pounds Newtons
in 2 m2

71. Some Gas Problems
Convert 34 psi to Pa.
101,325 Pa = 14.7 psi

72. What is blood pressure?
The liquid inside your
blood vessels is
compressed by the
elastic nature of the
vessel walls.
Your blood pressure is
usually 80 mm Hg
greater than the
atmospheric pressure

73. What is blood pressure?
The liquid inside your
blood vessels is
compressed by the
elastic nature of the
vessel walls.
When your heart
contracts, the
pressure goes up
even more!
. . . Perhaps to 120
mm Hg greater than
atmospheric!

75. In 1662, Robert Boyle discovered an inverse
relationship between the pressure exerted
by a gas and its volume.
http://elementy.ru/images/eltbio/boyle_robert_180.jpg

76. In 1662, Robert Boyle discovered an inverse
relationship between the pressure exerted
by a gas and its volume.
1 atm
2 atm
4 atm
(As long as the temp was kept the same)

77. In 1662, Robert Boyle discovered an inverse
relationship between the pressure exerted
by a gas and its volume.
Examine his data:
20 mL 1 atm = 20 mL.atm
10 mL 2 atm = 20 mL.atm
5 mL 4 atm = 20 mL.atm
In other words . . .
P V = constant

78. In 1662, Robert Boyle discovered an inverse
relationship between the pressure exerted
by a gas and its volume.
this is known as Boyle’s law
P V = constant

79. using Boyle’s law
When atmospheric pressure = 14.9 psi, a sample of air
has a volume of 30 mL. What will the volume of the air
sample be when atmospheric pressure drops to 14.5 psi?
first, let’s find the constant:
14.9psi 30mL = 447 psi.mL
P V = constant

80. using Boyle’s law
When atmospheric pressure = 14.9 psi, a sample of air
has a volume of 30 mL. What will the volume of the air
sample be when atmospheric pressure drops to 14.5 psi?
Now, use the constant to find the new volume:
14.9psi 30mL = 447 psi.mL
14.5psi V = 447 psi.mL

81. using Boyle’s law
When atmospheric pressure = 14.9 psi, a sample of air
has a volume of 30 mL. What will the volume of the air
sample be when atmospheric pressure drops to 14.5 psi?
Now, use the constant to find the new volume:
14.5psi V = 447 psi.mL

82. using Boyle’s law
When atmospheric pressure = 14.9 psi, a sample of air
has a volume of 30 mL. What will the volume of the air
sample be when atmospheric pressure drops to 14.5 psi?
Now, use the constant to find the new volume:
14.5psi V = 447 psi.mL
447 psi ×mL
V 31mL
14.5 psi

83. using Boyle’s law
When atmospheric pressure = 14.9 psi, a sample of air
has a volume of 30 mL. What will the volume of the air
sample be when atmospheric pressure drops to 14.5 psi?
We often see Boyle’s law written as P1V1 = P2V2
P1 = 14.9psi
14.9psi 30mL = 14.5psi V2
V1 = 30mL
P2 = 14.5psi V2 = 31mL
V2 = ?

84. In 1787, Jacques Charles discovered that the
temperature and volume of a gas are
proportional
http://content.answers.com/main/content/wp/en-commons/thumb/b/b7/250px-
Jacques-Charles_Dupont_de_L'Eure.jpg

85. In 1787, Jacques Charles discovered that the
temperature and volume of a gas are
proportional
ice bath at 0 C

86. In 1787, Jacques Charles discovered that the
temperature and volume of a gas are
proportional
boiling water at 100 C
20 mL of a gas at 0 C will occupy 27.3 mL at 100 C
(as long as atmospheric pressure isn’t changed)

87. If temperature is in degrees Kelvin, we have the following:
V
Constant
T
this is known as charles’ law
V1 V2
We often see Charles’ law written as =
T1 T2

88. using charles’ law
A sample of steam at 100 C has a volume of 240 mL.
What will the new volume be if the steam is cooled to 0 C?
first, let’s convert our temps to kelvin:
100C + 273 = 373K

89. using charles’ law
A sample of steam at 100 C has a volume of 240 mL.
What will the new volume be if the steam is cooled to 0 C?
first, let’s convert our temps to kelvin:
100C + 273 = 373K
0C + 273 = 273K

90. using charles’ law
A sample of steam at 100 C has a volume of 240 mL.
What will the new volume be if the steam is cooled to 0 C?
first, let’s convert our temps to kelvin:
100C + 273 = 373K
0C + 273 = 273K
V1 = 240 mL
T1 = 373K 240 mL V2
V2 = ? = V2 = 176 mL
373K 273K
T2 = 273K

91. Combined Gas Law
• Derived from a combination of Boyle’s
law and Charles’s law
• Change involving volume, pressure, and
temperature simultaneously
PiVi Pf V f
=
Ti Tf

92. Using the Combined Gas Law
• Calculate the volume of N2 resulting when
0.100 L of the gas is heated from 300. K to
350. K at 1.00 atm
PiVi Pf V f
• What do we know? =
Ti Tf
– Pi = 1.00 atm Pf = 1.00 atm
– Vi = 0.100 L Vf = ? L
– Ti = 300. K Tf = 350. K
• Vf = ViTf / Ti this is valid as Pi = Pf
• Vf = (0.100 L)(350. K) / 300. K = 0.117 L

94. Many of the “most important” gases aren’t
pure, but are actually mixtures.

95. What is the composition of air?
For every 1,000,000 “air” molecules, . . .
780,810 N2 molecules
209,480 O2 molecules
9,340 Ar atoms
345 CO2 molecules
18 Ne atoms
5 He atoms
2 CH4 molecules
This is only true of dry, nonpolluted air.

96. What is the composition of air?
In urban areas, the following pollutant
molecules can be fairly abundant:
CO molecules
NO molecules
NO2 molecules
SO2 molecules
O3 molecules
http://www.photo.net/photo/pcd0222/los-angeles-downtown-45.4.jpg

97. Consider a Rain Forest in Belize.
Costa Rican rainforest
http://www5.worldisround.com/photos/5/282/505_o.jpg

98. Consider a Rain Forest in Belize.
Costa Rican rainforest
At 86 F and 95% humidity, we have:
749,730 N2 molecules
201,140 O2 molecules Water can be
the 3rd most
39,810 H2O molecules
abundant
8,970 Ar atoms gas in air!
330 CO2 molecules
17 Ne atoms
3 He atoms
http://www5.worldisround.com/photos/5/282/505_o.jpg

99. The amount of H2O in air is highly dependent
on weather and geography.
Consider Vostok, Antarctica:
http://salegos-scar.montana.edu/images/Vostok%20Station.JPG

100. The amount of H2O in air is highly dependent
on weather and geography.
Consider Vostok, Antarctica:
At -76 F and 34% humidity, we have:
780,810 N2 molecules
209,480 O2 molecules
9,340 Ar atoms
345 CO2 molecules
18 Ne atoms
4 He atoms
3 H2O molecules
http://salegos-scar.montana.edu/images/Vostok%20Station.JPG

101. The amount of H2O in air is highly dependent
on weather and geography.
Whether a gas is pure or a mixture, it
still oBeys Boyle’s law and charles’ law
However, in a mixture of gases, the total
pressure equals the sum of the
pressures due to each component
http://salegos-scar.montana.edu/images/Vostok%20Station.JPG

102. Why should you care?

103. Breathing air that is
roughly 20% O2 means
that 80% of the
molecular collisions in
your lungs are useless.

104. Breathing 100% O2
increases the “partial
pressure” of O2

106. Liquids are . . .
•Not compressible
•Not organized
Liquids have . . .
Viscosity Vapor Pressure
Surface Tension Density

107. The Properties of Most Liquids Can be
Rationalized
in Terms of Their Intermolecular Forces
Liquids have a surface tension (an edge effect)
Compare the attractive
forces these molecules
have for their
neighbors!

108. Liquids have a “Skin”!
Because it can hydrogen-bond, water’s
skin is particularly tough!

109. Liquids have a “Skin”!
Liquids with weak intermolecular attractive
forces have less surface tension.

110. Liquids have a “Skin”!
Water’s high surface tension causes it
to “bead up” into large drops.
Liquids with weak intermolecular
attractive forces have smaller drops.

111. Liquids have a viscosity
Which pours more
easily, a jar of marbles
or a jar of gummy bears?

112. Liquids have a viscosity
Which pours more
easily, gummy bears or
gummy worms?

113. Liquids have a viscosity
Long, flexible molecules
with strong
intermolecular forces are
most viscous.

114. Liquids have a vapor pressure
What happens when a liquid is poured into a perfectly
empty container and the container is sealed?

115. Liquids have a vapor pressure
Some of the molecules at the surface evaporate.

116. Liquids have a vapor pressure
But the number of gas molecules only increases to a point.

117. Liquids have a vapor pressure
Some of the gas molecules bump back
into the liquid layer, slow down, and “re-stick”.

118. Liquids have a vapor pressure
When the number leaving the liquid equals the number re-
entering the liquid, we have an “equilibrium”.

119. Liquids have a vapor pressure
When equilibrium is reached, molecules with strong
intermolecular attractive forces look like this.

120. Liquids have a vapor pressure
When equilibrium is reached, molecules with weak
intermolecular attractive forces look like this.

121. What is melting? What is subliming?

122. “Deposition” is the opposite of sublimation.