PRINCIPALS OF CHEMISTRY I
(CEM 141)
Dr. BÙI THỊ BỬU HUÊ
College of Science
Cantho University
Chapter 1. MATTER AND MEASUREMENT
Chapter 2. ATOMS, MOLECULES AND IONS
Chapter 3. STOICHIOMETRIC
Chapter 4. ATOMIC STRUCTURE AND THE
PERIODIC TABLE
Chapter 5. CHEMICAL BONDS AND
MOLECULAR STRUCTURE
Chapter 6. STATES OF MATTER
Chapter 7. ENERGY AND CHEMICAL REACTIONS
Chapter 8. SOLUTIONS
Chapter 9. CHEMICAL EQUILIBRIA
References
1. Brady and Holum. 1996. Chemistry: the Study
of Matter and its Changes.
2th Ed., John Wiley & Sons. Inc. New York.
2. Umland, Jean B., 1993. General Chemistry.
West publishing company.
3. Zumdahl, Steven S. 1995. Chemical Principal.
2th Ed. DC. Health & company. Toronto.
4. http://www.chemistry.msu.edu/Courses/
5. http://antoine.frostburg.edu
6. http://chemed.chem.purdue.edu
7. http://www.chem1.com/chemed/genchem.html
8. http://www.cbu.edu/~mcondren/lectures.htm
9. http://ull.chemistry.uakron.edu/GenChem/index.html
Chapter 4. ATOMIC STRUCTURE AND
THE PERIODIC TABLE
Objectives
 Understand atomic structure of an atom
including its mass number, isotopes and orbitals.
 Know how to account for the structure of the
periodic table of the elements based on the modern
theory of atomic structure.
 Understand general trends of several important
atomic properties.
Chapter 4. ATOMIC STRUCTURE AND
THE PERIODIC TABLE
Atomic Structure
An atom is composed of three types of subatomic
particles: the proton, neutron, and electron.
Particle
Mass (g)
Charge
Proton
1.6727 x10 -24
+1
Neutron
1.6750 x10 -24
0
Electron
9.110 x 10
-28
-1
Atomic Structure
Atomic Structure
Electromagnetic Radiation
Electromagnetic Radiation
nl= c
Where:
n: frequency
l: wavelength
c: speed of light
Electromagnetic Spectrum
Dispersion of White Light
Photoelectric Effect
• the emission of electrons by
substances, especially metals, when
light falls on their surfaces.
Photoelectric Effect
Quantum Mechanics
• Quantum theory
the theory of the structure and
behavior of atoms and molecules.
Photons
The quantum of electromagnetic energy,
generally regarded as a
discrete particle having zero mass, no
electric charge, and an indefinitely
long lifetime.
E = hν = hc/λ
h = Planck's constant = 6.626 × 10−34 J.s
Line Emission Spectrum
Absorption Spectrum
 Light shinning on
a sample causes
electrons to be
excited from the
ground state to
an excited state
 wavelengths of
that energy are
removed from
transmitted spectra
The Atomic Spectrum of Hydrogen
and the Bohr Model
Bohr Model for the Hydrogen Atom
mvr = nh/2p
n = quantum number
n = 1, 2, 3, 4, 5, 6, 7, etc
Bohr Atom
Ground State
The state of least possible energy in
a physical system, as of elementary
particles. Also called ground level.
Excited State
Being at an energy level higher
than the ground state.
Electron Transition in a Hydrogen Atom
Lyman series → ultraviolet
n>1→ n=1
Balmer series → visible light
n>2→n=2
Paschen series → infrared
n>3→ n=3
Knowing diamond is transparent, which
curve best represents the absorption
spectrum of diamond (see below)?
A, B, C
According to the energy diagram below
for the Bohr model of the hydrogen
atom, if an electron jumps from E1 to
E2, energy is
absorbed
emitted
not involved
Orbitals
• region of probability of finding an
•
electron around the nucleus
4 types: s, p, d, f
Atomic Orbitals, s-type
Atomic Orbitals, p-type
Atomic Orbitals, d-type
Pauli Exclusion Principle
Electronic Configurations
• The shorthand representation of the
occupancy of the energy levels (shells
and subshells) of an atom by electrons.
Hund's Rules
Electronic Configuration
1
H atom (1 electron):
1s
2
He atom (2 electrons):
1s
2
1
Li atom (3 electrons):
1s , 2s
Cl atom
(17 electrons):
1s2, 2s2, 2p6, 3s2, 3p5
Electronic Configuration
As atom
33 electons:
2
2
6
2
6
2
10
3
1s , 2s , 2p , 3s , 3p , 4s , 3d , 4p
or
[Ar] 4s2, 3d10, 4p3
Mn: [Ar]4s2 3d?
How many d electrons does Mn have?
4, 5, 6
Electronic Configuration
Negative ions:
add electron(s), 1 electron for each
negative charge
S-2 ion:
(16 + 2)electrons:
1s2, 2s2, 2p6, 3s2, 3p6
Electronic Configuration
Positive ions
remove electron(s), 1 electron for each
positive charge
Mg+2 ion: (12-2) electrons
1s2, 2s2, 2p6
How many valence electrons are in Cl,
[Ne]3s2 3p5?
2, 5, 7
For Cl to achieve a noble gas
configuration, it is more likely that
electrons would be added
electrons would be removed
Regions by Electron Type
Trends in the Periodic Table
•
•
•
•
atomic radius
ionic radius
ionization energy
electron affinity
Atomic Radius
decrease left to right across a period
Zeff = Z - S
where
Zeff = effective nuclear charge
Z = nuclear charge, atomic number
S = shielding constant
Atomic Radius
 Increase top to bottom down a group
 Increases from upper right corner to
the lower left corner
Atomic Radius
Atomic Radius vs. Atomic Number
Ionic Radii
Ionic Radius
• Same trends as for atomic radius
• positive ions smaller than atom
• negative ions larger than atom
Comparison of Atomic and Ionic Radii
Ionic Radius
Isoelectronic Series
• series of negative ions, noble gas atom,
and positive ions with the same electronic
confiuration
• size decreases as “positive charge” of the
nucleus increases
Ionization Energy
• energy necessary to remove an electron to
•
•
•
form a positive ion
low value for metals, electrons easily
removed
high value for non-metals, electrons
difficult to remove
increases from lower left corner of
periodic table to the upper right corner
Ionization Energies
first ionization energy
• energy to remove first electron from an
atom.
second ionization energy
• energy to remove second electron from a
+1 ion.
etc.
Ionization Energy vs. Atomic Number
Electron Affinity
• energy released when an electron is
•
•
•
added to an atom
same trends as ionization energy,
increases from lower left corner to the
upper right corner
metals have low “EA”
nonmetals have high “EA”
Magnetism
• Result of the spin of electrons
• diamagnetism - no unpaired electrons
• paramagnetism - one or more unpaired
electrons
Magnetism
Without applied field
With applied field