principals of chemistry i (cem 141) dr. bÙi thỊ bỬu huÊ college of science cantho university
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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 - PowerPoint PPT PresentationTRANSCRIPT
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
ReferencesReferences
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.edu6. http://chemed.chem.purdue.edu7. http://www.chem1.com/chemed/genchem.html8. http://www.cbu.edu/~mcondren/lectures.htm9. http://ull.chemistry.uakron.edu/GenChem/index.html
Chapter 4. Chapter 4. ATOMIC STRUCTURE AND ATOMIC STRUCTURE AND THE PERIODIC TABLETHE 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. Chapter 4. ATOMIC STRUCTURE AND ATOMIC STRUCTURE AND
THE PERIODIC TABLETHE 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
ElectromagneticElectromagnetic RadiationRadiation
Electromagnetic RadiationElectromagnetic Radiation
ccWhere:Where:
frequencyfrequency
wavelengthwavelength
c: speed of lightc: speed of light
Electromagnetic Spectrum
Dispersion of White LightDispersion of White Light
Photoelectric EffectPhotoelectric Effect
• the emission of electrons by the emission of electrons by substances, especially metals, when substances, especially metals, when light falls on their surfaces. light falls on their surfaces.
Photoelectric EffectPhotoelectric Effect
Quantum MechanicsQuantum Mechanics
• Quantum theoryQuantum theory
the theory of the structure and the theory of the structure and behavior of atoms and molecules.behavior of atoms and molecules.
PhotonsPhotons
The quantum of electromagnetic energy,The quantum of electromagnetic energy,generally regarded as agenerally regarded as adiscrete particle having zero mass, nodiscrete particle having zero mass, noelectric charge, and an indefinitelyelectric charge, and an indefinitelylong lifetime.long lifetime.E = hE = hνν = hc/ = hc/λλ
h = Planck's constant = 6.626 h = Planck's constant = 6.626 × 10× 10−34 −34 J.sJ.s
Line Emission Spectrum
Absorption SpectrumAbsorption Spectrum Light shinning on Light shinning on
a sample a sample causes causes electrons electrons to be to be excited from excited from the the ground state to ground state to
an excited statean excited state wavelengths wavelengths
of of that energy are that energy are removed from removed from
transmitted spectratransmitted spectra
The Atomic Spectrum of HydrogenThe Atomic Spectrum of Hydrogen and the Bohr Model and the Bohr Model
Bohr Model for the Hydrogen AtomBohr Model for the Hydrogen Atom
mvr = nh/2mvr = nh/2n = quantum numbern = quantum number
n = 1, 2, 3, 4, 5, 6, 7, etcn = 1, 2, 3, 4, 5, 6, 7, etc
Bohr AtomBohr Atom
Ground StateGround State
The state of least possible energy in The state of least possible energy in a physical system, as of elementary a physical system, as of elementary particles. Also called particles. Also called ground level.ground level.
Excited StateExcited State
Being at an energy level higher Being at an energy level higher than the ground state.than the ground state.
Electron Transition in a Hydrogen AtomElectron 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, Knowing diamond is transparent, which curve best represents the which curve best represents the absorption spectrum of diamond (see absorption spectrum of diamond (see below)?below)?
A, B, CA, B, C
According to the energy diagram According to the energy diagram below for the Bohr model of the below for the Bohr model of the hydrogen atom, if an electron jumps hydrogen atom, if an electron jumps from E1 to E2, energy isfrom E1 to E2, energy is
absorbedabsorbed
emittedemitted
not involvednot involved
OrbitalsOrbitals
• region of probability of finding an region of probability of finding an electron around the nucleuselectron around the nucleus
• 4 types: s, p, d, f4 types: s, p, d, f
Atomic Orbitals, s-type
Atomic Orbitals, p-typeAtomic Orbitals, p-type
Atomic Orbitals, d-typeAtomic Orbitals, d-type
Pauli Exclusion PrinciplePauli Exclusion Principle
Electronic ConfigurationsElectronic Configurations
• The shorthand representation of the The shorthand representation of the occupancy of the energy levels (shells occupancy of the energy levels (shells and subshells) of an atom by electrons.and subshells) of an atom by electrons.
Hund's Rules
Electronic ConfigurationElectronic Configuration
H atom H atom (1 electron): (1 electron): 1s1s11
He atom (2 electrons):He atom (2 electrons): 1s1s22
Li atomLi atom (3 electrons):(3 electrons): 1s1s22, 2s, 2s11
Cl atomCl atom
(17 electrons):(17 electrons): 1s1s22, 2s, 2s22, 2p, 2p66, 3s, 3s22, 3p, 3p55
Electronic ConfigurationElectronic Configuration
As atomAs atom
33 electons:33 electons:
1s1s22, 2s, 2s22, 2p, 2p66, 3s, 3s22, 3p, 3p66, 4s, 4s22, 3d, 3d1010, 4p, 4p33
oror
[Ar] 4s[Ar] 4s22, 3d, 3d1010, 4p, 4p33
Mn: [Ar]4sMn: [Ar]4s22 3d 3d??
How many d electrons does Mn have?How many d electrons does Mn have?
4, 5, 6 4, 5, 6
Electronic ConfigurationElectronic Configuration
Negative ionsNegative ions::
add electron(s), 1 electron for eachadd electron(s), 1 electron for each
negative chargenegative charge
SS-2-2 ion: ion: (16 + 2)electrons:(16 + 2)electrons:
1s1s22, 2s, 2s22, 2p, 2p66, 3s, 3s22, 3p, 3p66
Electronic ConfigurationElectronic Configuration
Positive ionsPositive ionsremove electron(s), 1 electron for eachremove electron(s), 1 electron for each
positive chargepositive charge
MgMg+2+2 ion: (12-2) electrons ion: (12-2) electrons
1s1s22, 2s, 2s22, 2p, 2p66
How many valence electrons are in How many valence electrons are in Cl, [Ne]3sCl, [Ne]3s22 3p 3p55??
2, 5, 72, 5, 7
For Cl to achieve a noble gas For Cl to achieve a noble gas configuration, it is more likely thatconfiguration, it is more likely that
electrons would be addedelectrons would be added
electrons would be removedelectrons would be removed
Regions by Electron TypeRegions by Electron Type
Trends in the Periodic TableTrends in the Periodic Table
• atomic radiusatomic radius
• ionic radiusionic radius
• ionization energyionization energy
• electron affinityelectron affinity
Atomic RadiusAtomic Radius
decrease left to right across a perioddecrease left to right across a period
Zeff = Z - Swhere Zeff = effective nuclear charge
Z = nuclear charge, atomic number
S = shielding constant
Atomic RadiusAtomic Radius
Increase top to bottom down a groupIncrease top to bottom down a group Increases from upper right corner to Increases from upper right corner to
the lower left cornerthe lower left corner
Atomic RadiusAtomic Radius
Atomic Radius vs. Atomic Number
Ionic RadiiIonic Radii
Ionic RadiusIonic Radius
• Same trends as for atomic radiusSame trends as for atomic radius
• positive ions smaller than atompositive ions smaller than atom
• negative ions larger than atomnegative ions larger than atom
Comparison of Atomic and Ionic RadiiComparison of Atomic and Ionic Radii
Ionic RadiusIonic Radius
Isoelectronic SeriesIsoelectronic Series
• series of negative ions, noble gas atom, series of negative ions, noble gas atom, and positive ions with the same electronic and positive ions with the same electronic confiurationconfiuration
• size decreases as “positive charge” of the size decreases as “positive charge” of the nucleus increasesnucleus increases
Ionization EnergyIonization Energy
• energy necessary to remove an electron to energy necessary to remove an electron to form a positive ionform a positive ion
• low value for metals, electrons easily low value for metals, electrons easily removedremoved
• high value for non-metals, electrons high value for non-metals, electrons difficult to removedifficult to remove
• increases from lower left corner of increases from lower left corner of periodic table to the upper right corner periodic table to the upper right corner
Ionization EnergiesIonization Energies
first ionization energyfirst ionization energy• energy to remove first electron from an energy to remove first electron from an
atom.atom.
second ionization energysecond ionization energy• energy to remove second electron from a energy to remove second electron from a
+1 ion.+1 ion.
etc.etc.
Ionization Energy vs. Atomic NumberIonization Energy vs. Atomic Number
Electron AffinityElectron Affinity
• energy released when an electron is energy released when an electron is added to an atomadded to an atom
• same trends as ionization energy, same trends as ionization energy, increases from lower left corner to the increases from lower left corner to the upper right cornerupper right corner
• metals have low “EA”metals have low “EA”
• nonmetals have high “EA”nonmetals have high “EA”
MagnetismMagnetism
• Result of the spin of electronsResult of the spin of electrons
• diamagnetism - no unpaired electronsdiamagnetism - no unpaired electrons
• paramagnetism - one or more unpaired paramagnetism - one or more unpaired electronselectrons
MagnetismMagnetism
Without applied field With applied field