PRINCIPALS OF CHEMISTRY I (CEM 141) Dr. BÙI THỊ BỬU HUÊ College of Science Cantho University

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