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Transcript
What you should gain
1. An understanding of some of the
principles and theories.
2. Improvement of your problem-solving
skills.
3. Improvement in your scientific knowledge
by understanding scientific reading.
4. Improvement in your communication and
independent learning skills.
Resources for YOU
You need to keep track of how you are doing in the class and
take action if you fall behind or have trouble with the material.
A. Fellow students - meet others in the class. Even though
you and the other student may be perplexed about a
subject, you will find that talking together in the language of
chemistry may help you out of a trouble.
B. Your instructor(s) - I am especially willing to answer
questions in class, and I am available most of the working
week (10am - 5:30 pm) in my office or on the 4th floor of
Lappin to answer questions if I don't have a class. Your lab
instructor (if you have a different one) or indeed any of the
chemistry faculty are usually willing to help out if you need
help.
C. Tutors are available. One or more may be available on the
second floor of Allie Young (783-5200). Book tutors early as
they tend to be booked up by the second week of the
semester.
Why Chemistry ????
Consider these: Pain Killers
Morphine – Analgesic extracted from the
opium plant.
Reacts with receptors in the brain, and reduces
the sensation of pain.
Heroine – Illegal drug with effects similar to
morphine, but considerably more
addictive.
Codeine – Also used as a pain killer, but with
1/10 the potency of morphine.
Thebaine – Similar to codeine, with one
exception, it causes convulsions if
ingested.
Chemical formula and structure
HO
O
O
Morphine
O
N
O
H
O
O
O
Codeine
N
O
H
HO
Heroine
Thebaine
O
O
N
N
HO
H
O
H
Chapter One
Matter and Life
The Central Science
Chemistry is often referred to as “The Central
Science” because it is crucial to all other sciences.
Matter: Anything that has mass and
occupies space – things you can see,
touch, taste, or smell.
Property: a characteristic that can be used
to describe a substance. Size, color,
temperature are most familiar properties
of matter.
Chemical composition
Chemical Reactivity
Physical Change: Does not alter the
chemical makeup of a substance. Change is
reversible. Melting of solid ice is a physical
change.
Chemical Change: Alters chemical makeup of
a substance. Change is irreversible. Rusting
of iron is a chemical change. Here, iron
combines with oxygen and produces a new
substance rust.
States of Matter
Solid: A substance that has a definite shape
and volume.
Liquid: A substance that has a definite volume
but that changes shape to fill the container.
Gas: A substance that has neither a definite
volume nor a definite shape.
Many substances, such as water, can exist in
all three states depending on the temperature.
The conversion of a substance from one state
into another is known as change of state.
The three states
Solid state
Liquid state
Gaseous state
Classification of Matter
Pure Substance: Uniform in its chemical
composition and properties. Sugar and
water are pure substances.
Mixture: Composition and properties may
vary. Different amounts of sugar dissolved
in water will determine sweetness of water.
Sugar water is an example of a mixture.
Chemical Compounds: Substance that can
be broken down into simpler substances.
Element: Substance that can not be
brokendown chemically into simpler
substances.
The classification of matter
Fig. 1.4
Chemistry is a science that describes
Physical properties
Composition
Structure
Reactions
of Matter
Matter: Anything that has mass and occupies
space – things you can see, touch, taste,
or smell.
Property: a characteristic that can be used to
describe a substance. Size, color,
temperature are most familiar properties of
matter.
Physical Change: Does not alter the
chemical makeup of a substance.
Change is reversible. Melting of
solid ice is a physical change.
Chemical Change: Alters chemical makeup
of a substance. Change is irreversible.
Rusting of iron is a chemical change.
Here, iron combines with oxygen and
produces a new substance rust.
Classification of Matter
Pure Substance: Uniform in its chemical
composition and properties. Sugar and
water are pure substances.
Mixture: Composition and properties may
vary. Different amounts of sugar
dissolved in water will determine
sweetness of water. Sugar water is an
example of a mixture.
Chemical Compounds: Substance that can
be broken down into simpler substances.
Element: Substance that can not be brokendown
chemically into simpler substances.
States of Matter
Solid: A substance that has a definite shape
and volume.
Liquid: A substance that has a definite volume
but that changes shape to fill the container.
Gas: A substance that has neither a definite
volume nor a definite shape.
Many substances, such as water, can exist in
all three states depending on the temperature.
The conversion of a substance from one state
into another is known as change of state.
The three states
The classification of matter
Fig. 1.4
Chemical Elements and Symbols
113 Elements are known until today. Only
90 of these elements occur naturally,
remaining are produced artificially by
chemists and physicist.
Some familiar elements are iron, tin,
carbon, oxygen, hydrogen, sulfur, etc.
Some unfamiliar elements are niobium,
rhodium, thulium, californium etc.
Each element has its own unique symbol.
– One or two letter symbols are used to
represent elements.
– First letter is always capitalized and the
second letter is always a lower case.
– All naturally occurring elements are not equally
abundant. Oxygen and silicon together
constitute 75% of the earth’s crust.
Chemical Formula: A notation for
chemical compound using element
symbols and subscripts to show how
many atoms of each element are
present.
The formula for water is H2O. H2O indicates that two
hydrogen and one oxygen combined together to produce
water. When no subscript is given for an element a
subscript of ‘1’ is understood.
Water
Methane
Amino acid
O
H
O
H
H
H2O
H2N
C
H
CH
C
OH
H
H
CH4
CH3
C3H7NO2
2 H atoms
4 H atoms
7 H atoms
1 O atom
1 C atom
3 C atoms
1 N atom
2 O atoms
Elements and the Periodic Table
•Periodic Table, is a representation of 113
elements in a tabular format.
Metals: 89 of the 113 elements appear on
the left side of the Periodic Table.
Some common properties of metals are:
 Solid at room temperature (except mercury
which is a liquid)
 Good conductor of heat
 Good conductor of electricity
 Malleable.
Nonmetals: Appears on the right side of
the Periodic Table.
17 elements are
nonmetals.
Nonmetals are poor conductor of heat and
electricity.
Out of these 17 nonmetal elements
– Eleven are gases at room temperature (H,
N, O, etc.)
– Five are solids (sulfur)
– One is a liquid (bromine).
•Metalloids: Appears between metals
and nonmetals on the periodic table.
Their properties are between metals and
nonmetals. Boron, silicon, arsenic are
examples of some of the metalloids.
Lecture 3
Chapter Summary
•Chemistry is the study of matter.
•Matter is anything that has mass and
occupies space.
•Physical change does not alter the
chemical makeup of a substance. Change is
reversible.
•Chemical change alters chemical makeup
of a substance. Change is irreversible.
•Pure substances have uniform chemical
composition and properties.
Composition and properties of a mixture may
vary.
•
•
•Substance
that can be broken down into simpler
substances is a chemical compound.
•
•Substance
that can not be broken down
chemically into simpler substances is known as
an element.
•
•Elements
symbols.
are represented by one or two letter
Elements and the Periodic Table
•Periodic Table, is a representation of 113
elements in a tabular format.
• Chemical
Formula is a notation for
chemical compound to show how many
atoms of each element are present.
• H 2O
•
•Elements
are roughly divided into 3 groups
– Metals
– Nonmetals
– Metalloids
Chapter Three
Atoms and the Periodic
Table
Atomic Theory
•1. All Matter is composed of atoms.
•2. The atoms of a given element differ
from the atoms of all other elements.
•3. Chemical compounds consist of atoms
combined
in specific ratios (formulas).
•4. Chemical reactions change only the
way the atoms are combined in
compounds; the atoms themselves are
unchanged.
•
•
•
•
Atoms are composed of tiny subatomic
particles called protons, neutrons, and
electrons.
Name
Proton
Neutron
Electron
Symbol
p
n
e-
(grams)
1.672622 x 10-24
1.674927x10-25
9.109328x10-28
(amu)
1.007267
1.008665
5.485799x10-4
Charge
+1
0
-1
Since the masses of atoms and their constituent
subatomic particles are so small when
measured in grams that their masses are
expressed on a relative mass scale.
The basis for the relative atomic mass scale is
an atom of carbon that contain 6 protons and 6
neutrons. This carbon atom is assigned a mass
of exactly 12 atomic mass unit (amu).
•
Both a proton and a neutron have mass of 1
amu. Hydrogen atoms have mass of 1 amu,
oxygen atoms have mass of 16 amu, etc.
•
Subatomic particles are not
randomly throughout an atom.
•
The protons and neutrons are held together
closely in a dense core called the nucleus.
•
Surrounding the nucleus, the electrons move
about rapidly through a large, mostly empty
volume of space.
distributed
•
•
Diameter of a nucleus is only about 10-15 m .
Diameter of an atom is only about 10-10 m .
Fig 3.1 The structure of an atom
 The structure of the atom is determined by
an interplay of different attractive and
repulsive forces.
•
Unlike charges attract each other - the
negatively charged electrons are held close
to the nucleus due to this attraction.
•
Like charges repulse each other - two
negatively charged electrons try to get as far
away as possible occupying large volume in
space. The Positively charged protons in the
nucleus also repel each other, however, they
are held together by a unique attraction called
nuclear strong force.
• Question 3.39
• How many Na atoms of mass 22.99amu
are in 22.99g of sodium.
• 1amu = 1.660539 x 10 -24 g
• 22.99g x
________1amu
atom
•
1.660539 x 10-24g
amu
x Na
22.99
Lecture 4 and into lecture 5-6
Element and Atomic Number
•Atomic Number (Z): Number of protons
each atom of different elements contain in
their nucleus. We can identify the element
if we know the number of protons in the
nucleus.
•Mass Number (A): The total number of
protons and neutrons in an atom.
Isotopes and Atomic Weight
•Isotopes:
Atoms with identical
atomic
numbers (Z) but different mass numbers (A) are
called isotopes.
Hydrogen, deuterium, and
tritium are three isotopes of hydrogen.
• - Most abundant hydrogen isotope has one
proton and no neutron (A=1);
• - deuterium isotope has one proton and one
neutron (A=2), and
• - tritium isotope has one proton and two
neutrons (A=3).
Isotopes of hydrogen
•Atomic Weight: The weighted average
mass of an element’s atoms in a large
sample that includes all the naturally
occurring isotopes of that atom.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Isotope Table
Element
Mass
Abundance
Arsenic
Carbon
Chlorine
Isotope
Natural
Accurate
75As
12C
13C
74.92160
12.000000
13.003355
35Cl
34.968852
37Cl
Fluorine
Hydrogen
19F
1H
Nitrogen
18.998403
1.007825
14N
14.003074
16O
Silicon
Silver
Sodium
Sulfur
Tin
99.63%
15.994915
23Na
0.37%
99.76%
16.999131
17.999160
30.973762
81.916698
27.976927
28.976495
29.973770
106.905092
108.904757
22.989767
32S
33S
34S
112Sn
114Sn
115Sn
116Sn
117Sn
118Sn
119Sn
120Sn
122Sn
124Sn
0.015%
100.00%
5.80%
91.72%
2.20%
15.000108
17O
18O
31P
82Se
28Si
29Si
30Si
107Ag
109Ag
Phosphorus
24.23%
100.00%
99.985%
2.014102
126.904473
53.93961
55.93494
56.93540
15N
Oxygen
75.77%
36.965903
2H
127I
54Fe
56Fe
75Fe
Iodine
Iron
100.00%
98.90%
1.10%
0.04%
0.20%
100.00%
8.74%
92.23%
4.67%
3.10%
51.839%
48.161%
100.00%
31.972070
32.971456
33.967866
111.904826
113.902784
114.903348
115.901747
116.902956
117.901609
118.903310
119.90220
121.903440
123.905274
95.02%
0.75%
4.21%
0.97%
0.65%
0.36%
14.53%
7.68%
24.22%
8.58%
32.59%
4.63%
5.79%
From "The CRC Handbook of Chemistry and Physics", 73rd Edition, D. R. Lide, Ed., CRC Press, Ann Arbor, MI, 1992
-
Periodic Table
•Fig 3.2 The periodic
table
3.4 The Periodic Table
•
•
Beginning at the upper left corner of the
periodic table, elements are arranged by
increasing atomic number into seven
horizontal rows, called periods, and 18
vertical columns, called groups.
The elements in a given group have similar
chemical properties.
Lithium, sodium,
potassium and other elements in group 1A
have similar properties. Similarly, chlorine,
bromine, iodine, and other elements in
group 7A behaves similarly.
•The table has 113 boxes, each of which
tells the symbol, atomic number, and atomic
weight of an element.
 The first period contains only 2
elements.
 The second and third periods each
contains 8 elements.
 The fourth and fifth periods each
contains 18 electrons.
 The sixth period contains 32 electrons
 The seventh period, incomplete yet,
contains 27 elements.
•Main Groups: The two large groups on the far
left and the six on the far right are called the main
groups.
•Lanthanides: 14 elements following lanthanum
in group 6.
•Actinides:
14 elements following actinium
in group 7.
•Transition Metal Groups: Elements in the
groups numbered 1B through 8B.
•Inner Transition Metal Groups: The 14 groups
shown separately at the bottom of the table and
are not numbered.
3.5 Some Characteristics of
Different Groups
•
•
Various elements in a given group of the
periodic table show remarkable similarities in
their properties. For example,
Group 1A – Alkali metals: Lithium (Li), sodium
(Na), potassium (K), rubidium (Rb), cesium
(Cs), and francium (Fr) are shiny, soft, and
low melting metals. All reacts rapidly with
water to form products that are highly alkaline
or basic-hence the name alkaline metals.
•
Group 2A – Alkaline earth metals: Beryllium
(Be), magnesium (Mg), calcium (Ca),
strontium (Sr), barium (Ba), and radium (Ra)
are lustrous,, silvery metals. They are less
reactive than their neighbors.
•
Group 7A - Halogens: Fluorine (F), Chlorine
(Cl), Bromine (Br), Iodine (I), and astatine (At)
are colorful and corrosive nonmetals. All are
found in nature in combination with other
elements, such as with sodium in sodium
chloride (NaCl)
•
Group 8A-Noble gases: Helium (He),
neon (Ne), argon (Ar), krypton (Kr),
xenon (Xe), and radon
(Rn)
are
colorless gases of very low chemical
reactivity.
3. 6 Electronic Structure of Atoms
•
•
•
Quantum mechanical model of
atomic structure:
Electrons are not perfectly free to move
about in an atom.
Each electron is restricted to moving
about only in a certain region of space
within the atom, depending
on
the
amount of energy the electron has.
•
•
•
•
Different electrons have different
amounts of energy and thus occupy
different regions within the atom.
The energies of electrons are
quantized, or restricted to having only
certain values.
The electrons in an atom are grouped
around the nucleus into shells.
Within the shells, electrons are further
grouped into subshells of four different
types, identified as s, p, d, and f in
order of increasing energy.
•
The first shell has only an s
subshell
•
The second shell has an s and a p
subshell
•
The third shell has an s, a p, and
ad
subshell.
•
The fourth shell has an s, a p, a d,
and an f
subshell.
•
•
•
The number of subshells in a given shell is
equal to the shell number. For example, shell
number 3 has 3 subshells.
Within each subshell, electrons are further
grouped into orbitals, regions of space within
an atom where the specific electrons are more
likely to be found.
There are different number of orbitals within
the different kinds of subshells.
Different orbitals have different shapes.
Orbitals in s subshells are spherical (a), while
orbitals in p subshells are roughly dumbbell
shaped (b).
•
•
•
•
The first shell (nearest to the nucleus) can
hold only 2 electrons. They are in a single
1s orbital.
The second shell can hold 8 electrons – 2
in a 2s orbital and 6 in 3 2p orbitals.
The third shell can hold 18 electrons – 2 in
a 3s orbital, 6 in 3 3p orbitals, and 10 in 5
3d orbitals.
The fourth shell can hold 32 electrons – 2
in a 4s orbital, 6 are in 3 4p orbitals, 10 are
in 5 4d orbitals, and 14 are in 7 4f orbitals.
•The overall electron distribution within an
atom is summarized in table 3.2 shown
below.
3.7 Electron Configuration
•
Electron Configuration:
The exact
arrangement of electrons in atom’s shells and
subshells. Rules to predict electron
configuration:
1. Electrons occupy the lowest-energy orbitals
available, beginning with 1s and continuing in
order shown in the fig. 3.5.
2. Each orbital can hold only two electrons,
which must be oppositely spin.
3. Two or more orbitals with the same energy –
each orbital gets one electron before any
orbital gets two.
•Electrons fill orbitals in
energy orbitals upward.
numbered shells fill
However, some overlap
the third energy level.
Fig 3.5 order of orbital
energy levels
ascending order, from the lowestGenerally, this means that lowerbefore higher-numbered shells.
in energy levels occurs starting in
•Electronic configuration of a few elements
are shown below:
3.8 Electron Configuration and
the Periodic table
•The periodic table can be divided into
four regions or blocks, of elements
according to the shells and subshells as
shown in Fig 3.6.
•Valence Shell : Outermost shell of an
atom.
•Valence electrons: An electron in an
outermost shell of an atom.
These
electrons are loosely held, they are most
• Fig 3.6 electron configurations and the periodic
table
Chapter Summary
•
•
All matter is composed of atoms.
An atom is the smallest and simplest unit into
which an element can be divided while
maintaining the properties of the element.
• Atoms are made up of subatomic particles
called
protons, neutrons and electrons.
Protons have
positive, electrons have negative,
and neutrons have
zero electrical charges.
• Elements differ from each other according to
the number of protons their atoms contain
(Atomic
number, Z)
Chapter Summary Contd.
• Mass number (A): Total number of protons
and neutrons in an atom.
• Isotopes: Atoms with identical number of
protons
but different numbers of neutrons.
• Periodic table:
Tabular arrangement of
elements according to their valence shells.
• The electrons surrounding an atom are
grouped into
shells.
Within
each
shell,
electrons are grouped into subshells, and within
subshells into orbitals – regions of
space
where electrons are more likely to be found.
Chapter Summary Contd.
•
s orbitals are spherical and p orbitals are
bumbbell
shaped.
• Each orbital and each shell can hold a specific
number of electrons.
•- The first shell can hold only two electrons. 2
electrons in an s orbital (1S2).
•- The second shell can hold 8 electrons.
2 electrons in an s orbital and 6 electrons in
3 p orbitals. (2S2 2p6).
•- The third shell can hold 18 electrons. 2
electrons in an s orbital, 6 electrons in 3 p
orbitals, and 10 electrons in 5 d orbitals (3S2 3p6
3d10); and so on.