Structure of the AtomEdward A. Mottel

Department of Chemistry

Rose-Hulman Institute of Technology

04/18/23

Heated cathodesemitted cathode "rays"

+

-

Deflected by eithermagnetic or electric fields

Cathode Ray Tube

J.J. Thomson, 1897

Turn thefield on & offby clicking on the + & -

04/18/23

The "beam" carrieda negative charge. +

-

J. J. THOMSON (1897)British Physicist

The ratio of chargeto mass (e/m) was

independent ofthe cathode material.

Why does this indicate thatcathode rays (electrons)

are an integral part of each element?

How did heknow that?

04/18/23

Blackbody Radiation

According to classical theory,the intensity of black body radiation should

be related to wavelength.

1300 K

1800 K

2000 K

1000 3000 5000

Wavelength (nm)

Inte

nsi

ty In fact,

the intensity peakedand then dropped off.

04/18/23

Blackbody Radiation

1300 K

1800 K

2000 K

1000 3000 5000

Wavelength (nm)

Inte

nsi

ty This failure of theory in

the ultraviolet regionof the spectrum,

was called the

"UltravioletCatastrophe”.

It impliedthat theenergies inan atom are limited or quantized.

Based on this, Max Planck (1901, German Physicist) developed a quantum theory that electrons in an atom

can have only specific energies.

04/18/23

Photoelectric Effect

+ -

Albert Einstein (1905)German Physicist

Interpreted thePhotoelectric Effect

Confirmed thatlight is corpuscular(possess particle-like properties)Blue Red

Light SourceLight SourceLight Source

04/18/23

Oil Drop Experiment

+

-

Robert Millikin (1909)American Physicist

Determined theabsolute chargeof an electron(4.8 x 10–10 esu)

04/18/23

Gold Foil Experiment(10-4 cm thick)

Kotz & Purcell (1987)

Rutherford, 1911

04/18/23

Ernest Rutherford (1911)British Chemist

Most of the alpha particles(a, 4He2+) passed straightthrough, buta few weredeflected orreflectedstraightbackwards.

Since alpha particleswere known to have

a positive charge,this indicated thatthe nucleus of an

atom containedmost of the mass,

and that it waspositive in charge

Diagram source unknown

04/18/23

Niels Bohr (1913)(Danish Physicist)

Postulated that electrons spin around the nucleus in an orbit.

The energy differencesbetween these orbitscan be used to explainthe various colors of lightemitted and absorbedby gaseous elements.

04/18/23

Henry Moseley (1914)(British Physicist)

Developed a periodic table based on increasing atomic number.• Each element has an unique "spectra"

(wavelengths or colors of light) that they emit when heated to glowing.

04/18/23

Emission Spectra

• The spectra contains many colors (wavelengths) which are not uniformly spaced.

K bandL bandM band

Energy

04/18/23

Development of the Periodic Table

Element MassAtomic Number

K Inverse Sqrt(K)

Li 6.94 3 226.6 0.066Be 9.01 4 110.7 0.095B 10.81 5 66.3 0.123C 12.00 6 43.6 0.151N 14.01 7 31.0 0.180O 16.00 8 23.3 0.207

(Å)

04/18/23

K Radiation of Light Weight ElementsR2 = 0.9951

0.00

0.05

0.10

0.15

0.20

0.25

5 10 15 20

Mass (amu)

1/sq

rt(K

)

04/18/23

Integer Relationship of K RadiationR2 = 1

0.00

0.05

0.10

0.15

0.20

0.25

2 4 6 8 10

Integers

1/sq

rt(K

)

Atomic Number

04/18/23

Erwin Schrodinger (1926)(Austrian Physicist)

Developed the modern view of the atom, treating electrons as mathematical functions.• sine and cosine wave functions.

Louis de Broglie (1926)(French Physicist)

Proposed that matter has both wave and particle properties.

04/18/23

James Chadwick (1932)(British Physicist)

Determined the existence of the uncharged neutron.• Neutrons reside along with protons in the

nucleus and explain the fact that elements have isotopes.

04/18/23

Protons, Neutrons and Electrons

Fluorine atom

F199

charge(protons & electrons)

mass numberprotons & neutrons atomic number

(protons)

How many protons, neutrons and electronsare in a fluorine atom?

04/18/23

Protons, Neutrons and Electrons

Chloride ion

Cl–3717

charge(protons & electrons)

mass numberprotons & neutrons atomic number

(protons)

How many protons, neutrons and electronsare in a chloride ion?

04/18/23

Protons, Neutrons and Electrons

Aluminum ion

Al3+2713

How many protons, neutrons and electronsare in an aluminum ion?

04/18/23

Using the Periodic Table

Monatomic ions (ions containing only one atom) often have a charge that can be derived directly from the periodic table.

04/18/23

+1 ionsHLi Be

MgNa

K Ca

Rb Sr

CsBa

Ti CrMn Fe Co Ni CuZn

Pd

Pt

Ag

Au

Cd

Hg Tl

SnPb Bi

Sb

AsI

Br

Cl

O FSAl

04/18/23

+2 ions

Au

Ag

HLi Be

MgNa

K Ca

Rb Sr

CsBa

Ti CrMn Fe Co Ni CuZn

Pd

Pt

Cd

Hg Tl

SnPb Bi

Sb

AsI

Br

Cl

O FSAl

04/18/23

+3 ionsHLi Be

MgNa

K Ca

Rb Sr

CsBa

Ti CrMn Fe Co Ni CuZn

Pd

Pt

Ag

Au

Cd

Hg Tl

SnPb Bi

Sb

AsI

Br

Cl

O FSAl

04/18/23

-1 ionsHLi Be

MgNa

K Ca

Rb Sr

CsBa

Ti CrMn Fe Co Ni CuZn

Pd

Pt

Ag

Au

Cd

Hg Tl

SnPb Bi

Sb

AsI

Br

Cl

O FSAl

04/18/23

Coordination Compound NomenclatureEdward A. Mottel

Department of Chemistry

Rose-Hulman Institute of Technology

04/18/23

Coordination Compounds

Metal ion• the central atom

Ligand• atom, ion or molecule bound to the metal

The nomenclature of a salt anda coordination compound

are different.

04/18/23

Salt Nomenclature

FeCl3Fe3+ ion

iron(III) chloride

Salt (ionic) nomenclature only indicatesthe stoichiometry of the compound.

requires 3 Cl–

04/18/23

Coordination Compound Nomenclature

FeClClCl

Cl

Cl

Cl

3-hexachloroferrate(III) ion

Coordination compound nomenclaturecommunicates the environment of the central ion.

the iron ion is coordinatedto six chloride ligands

04/18/23

Coordination Compound Nomenclature

Fe

3+

OH

HOH

H

OH

H OH

HOH H

OH H

Coordination compound nomenclaturecommunicates the environment of the central ion.

hexaaquairon(III) ion

the iron ion is coordinatedto six water ligands

04/18/23

Nomenclature of Inorganic Coordination Compounds

Cation/anion sequence Ligand names Cationic/anionic complexes Alphabetical sequencing Brackets

04/18/23

[Cu(NH3)2Cl2]

[Cu(NH3)4]2+

[CuCl4]2–

Name each of the following

diamminedichlorocopper(II)

tetramminecopper(II) ion

tetrachlorocuprate(II) ion

04/18/23

Nomenclature of Inorganic Coordination Compounds

What is the meaning of Roman numerals in parenthesis?

When is copper used and when is cuprate used?

Meaning of the words aqua, ammine, cyano, chloro, bromo, iodo?

Application of the prefixes di, tri, tetra, … Order in which the words are used?

04/18/23

04/18/23

04/18/23

Heated cathodesemitted cathode "rays"

+

-

Deflected by eithermagnetic or electric fields

Cathode Ray Tube

J.J. Thomson, 1897

04/18/23

Photoelectric Effect

+ -

Albert Einstein (1905)German Physicist

Interpreted thePhotoelectric Effect

Confirmed thatlight is corpuscular(possess particle-like properties)