Reading Assignments:
Chapter 1 in
R. Chang, Chemistry, 9th Ed., McGraw-Hill,
2006. or previous editions.
Chemistry:
The Study of Change
Or related topics in other textbooks.
Consultation outside lecture room:
Office Hours:
Tuesday & Thursday
10 AM -12 noon,
Wednesday
1-4 PM
Chapter 1
@Room 313-3 or by appointment
Chemistry for Engineers, SCS126
Chemistry for Engineers, SCS126
Chemistry: A Science for the 21st Century
Chemistry: A Science for the 21st Century
• Health and Medicine
• Materials and Technology
• Sanitation systems
• Polymers, ceramics, liquid crystals
• Surgery with anesthesia
• Room-temperature superconductors?
• Vaccines and antibiotics
• Molecular computing?
•Energy and the Environment
• Food and Agriculture
• Fossil fuels
• Genetically modified crops
• Solar energy
• “Natural” pesticides
• Nuclear energy
• Specialized fertilizers
Chemistry for Engineers, SCS126
1.1
Chemistry for Engineers, SCS126
1.1
The Study of Chemistry
Macroscopic
Chemistry is the study of matter and the
changes it undergoes
Microscopic
1.
is anything that occupies space and
has mass.
2. A
is a form of matter that has a
definite composition and distinct properties.
Chemistry for Engineers, SCS126
1.2
Chemistry for Engineers, SCS126
1.4
Chemistry for Engineers, SCS126
An element is a substance that
be
separated into simpler substances by chemical
means.
•
elements have been identified
• 82 elements occur naturally on Earth
• 32 elements have been created by scientists
technetium, americium, seaborgium
Chemistry for Engineers, SCS126
1.4
Physical or Chemical?
A
is a substance composed of atoms of
two or more elements chemically united in fixed
proportions.
A physical change does not alter the composition
or identity of a substance.
Compounds can only be separated into their
pure components (elements) by chemical
means.
Water (H2O)
A chemical change alters the composition or
identity of the substance(s) involved.
Glucose (C6H12O6)
Ammonia (NH3)
Chemistry for Engineers, SCS126
1.4
Chemistry for Engineers, SCS126
Extensive and Intensive Properties
An
property of a material depends upon
how much matter is is being considered.
Atoms, Molecules and Ions
An
property of a material does not
depend upon how much matter is is being
considered.
Chemistry for Engineers, SCS126
Chapter 2
1.6
Chemistry for Engineers, SCS126
1.6
Reading Assignments:
Chapter 2 in
R. Chang, Chemistry, 9th Ed., McGraw-Hill,
2006. or previous editions.
Or related topics in other textbooks.
Consultation outside lecture room:
Office Hours:
Tuesday & Thursday
10 AM -12 noon,
Wednesday
1-4 PM
J.J. Thomson,
@Room 313-3 or by appointment
(1906 Nobel Prize
in Physics)
Chemistry for Engineers, SCS126 2.2
Chemistry for Engineers, SCS126
Cathode Ray Tube
(1923 Nobel Prize in Physics)
e- charge =
Thomson’s charge/mass of e- =
Chemistry for Engineers, SCS126
2.2
e- mass =
Chemistry for Engineers, SCS126
2.2
(1908 Nobel Prize in Chemistry)
α particle velocity ~ 1.4 x 107 m/s
(~5% speed of light)
1. atoms positive charge is concentrated in the nucleus
2. proton (p) has opposite (+) charge of electron (-)
3. mass of p is 1840 x mass of e- (1.67 x 10-24 g)
Chemistry for Engineers, SCS126
2.2
Rutherford’s Model of
the Atom
Chemistry for Engineers, SCS126
2.2
Chadwick’s Experiment (1932)
(1935 Noble Prize in Physics)
H atoms - 1 p; He atoms - 2 p
mass He/mass H should = 2
measured mass He/mass H = 4
atomic radius ~ 100 pm = 1 x 10-10 m
α + 9Be
1n
+ 12C + energy
nuclear radius ~ 5 x 10-3 pm = 5 x 10-15 m
Chemistry for Engineers, SCS126
2.2
Chemistry for Engineers, SCS126
2.2
Atomic number, Mass number and Isotopes
Atomic number (Z) = number of protons in nucleus
Mass number (A) = number of protons + number of neutrons
= atomic number (Z) + number of neutrons
are atoms of the same element (X) with different
numbers of neutrons in their nuclei
Mass Number
Atomic Number
Chemistry for Engineers, SCS126
2.2
The Isotopes of Hydrogen
A
ZX
Element Symbol
Chemistry for Engineers, SCS126
2.3
Do You Understand Isotopes?
14
How many protons, neutrons, and electrons are in 6 C ?
11
How many protons, neutrons, and electrons are in 6 C ?
Chemistry for Engineers, SCS126
2.3
Chemistry for Engineers, SCS126
2.3
A molecule is an aggregate of two or more atoms in a
definite arrangement held together by chemical forces
H2
H2O
NH3
CH4
A diatomic molecule contains only two atoms
H2, N2, O2, Br2, HCl, CO
A polyatomic molecule contains more than two atoms
O3, H2O, NH3, CH4
Chemistry for Engineers, SCS126
2.4
An ion is an atom, or group of atoms, that has a net
positive or negative charge.
Chemistry for Engineers, SCS126
2.5
A monatomic ion contains only one atom
cation – ion with a positive charge
If a neutral atom loses one or more electrons
it becomes a cation.
Na
11 protons
11 electrons
Na+
11 protons
10 electrons
A polyatomic ion contains more than one atom
anion – ion with a negative charge
If a neutral atom gains one or more electrons
it becomes an anion.
Cl
17 protons
17 electrons
Cl-
17 protons
18 electrons
Chemistry for Engineers, SCS126
2.5
Chemistry for Engineers, SCS126
2.5
Do You Understand Ions?
How many protons and electrons are in
27 3+
13 Al ?
How many protons and electrons are in
78
234 Se ?
Chemistry for Engineers, SCS126
2.5
2.5
ionic compounds consist of a combination of cations
and an anions
A
shows the exact number of
atoms of each element in the smallest unit of a
substance
• the formula is always the same as the empirical formula
• the sum of the charges on the cation(s) and anion(s) in each
formula unit must equal zero
An
shows the simplest
whole-number ratio of the atoms in a substance
molecular
Chemistry for Engineers, SCS126
The ionic compound NaCl
empirical
H2O
C6H12O6
O3
N2H4
Chemistry for Engineers, SCS126
2.6
Chemistry for Engineers, SCS126
2.6
Formula of Ionic Compounds
2 x +3 = +6
Al3+
1 x +2 = +2
Ca2+
1 x +2 = +2
Na+
3 x -2 = -6
O22 x -1 = -2
Br1 x -2 = -2
CO32Chemistry for Engineers, SCS126
2.6
Chemistry for Engineers, SCS126
• Molecular compounds
Chemical Nomenclature
• nonmetals or nonmetals + metalloids
• common names
• Ionic Compounds
• H2O, NH3, CH4, C60
– often a metal + nonmetal
– anion (nonmetal), add “ide” to element name
• element further left in periodic table
is 1st
• element closest to bottom of group is
1st
• if more than one compound can be
formed from the same elements, use
prefixes to indicate number of each
kind of atom
• last element ends in ide
barium chloride
potassium oxide
magnesium hydroxide
potassium nitrate
Chemistry for Engineers, SCS126
2.7
2.7
Chemistry for Engineers, SCS126
2.7
Molecular Compounds
hydrogen iodide
nitrogen trifluoride
SO2
sulfur dioxide
dinitrogen tetrachloride
NO2
nitrogen dioxide
TOXIC!
dinitrogen monoxide
Laughing Gas
Chemistry for Engineers, SCS126
2.7
Chemistry for Engineers, SCS126
2.7