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Structure of the Atom. Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology. +. -. Cathode Ray Tube. Turn the field on & off by clicking on the + & -. Heated cathodes emitted cathode "rays". Deflected by either magnetic or electric fields. J.J. Thomson, 1897.

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structure of the atom

Structure of the Atom

Edward A. Mottel

Department of Chemistry

Rose-Hulman Institute of Technology

cathode ray tube
+

-

Cathode Ray Tube

Turn the

field on & off

by clicking on

the + & -

Heated cathodes

emitted cathode "rays"

Deflected by either

magnetic or electric fields

J.J. Thomson, 1897

j j thomson 1897 british physicist
+

-

J. J. THOMSON (1897)British Physicist

The "beam" carried

a negative charge.

How did he

know that?

The ratio of charge

to mass (e/m) was

independent of

the cathode material.

Why does this indicate that

cathode rays (electrons)

are an integral part of each element?

blackbody radiation
2000 K

Intensity ®

1800 K

1300 K

1000

3000

5000

Wavelength (nm)

Blackbody Radiation

In fact,

the intensity peaked

and then dropped off.

According to classical theory,

the intensity of black body radiation should be related to wavelength.

blackbody radiation5
2000 K

Intensity ®

1800 K

1300 K

1000

3000

5000

Wavelength (nm)

Blackbody Radiation

This failure of theory in

the ultraviolet region

of the spectrum,

was called the

"Ultraviolet

Catastrophe”.

It implied

that the

energies in

an 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.

photoelectric effect
-

+

Photoelectric Effect

Albert Einstein (1905)German Physicist

Interpreted the

Photoelectric Effect

Confirmed that

light is corpuscular

(possess particle-like properties)

Blue

Red

Light Source

Light Source

Light Source

oil drop experiment
+

-

Oil Drop Experiment

Robert Millikin (1909)American Physicist

Determined the

absolute charge

of an electron

(4.8 x 10–10 esu)

gold foil experiment 10 4 cm thick
Gold Foil Experiment(»10-4 cm thick)

Kotz & Purcell (1987)

Rutherford, 1911

ernest rutherford 1911 british chemist
Ernest Rutherford (1911)British Chemist

Most of the alpha particles

(a, 4He2+) passed straight

through, but

a few were

deflected or

reflected

straight

backwards.

Since alpha particles

were known to have

a positive charge,

this indicated that

the nucleus of an

atom contained

most of the mass,

and that it was

positive in charge

Diagram source unknown

niels bohr 1913 danish physicist
Niels Bohr (1913)(Danish Physicist)
  • Postulated that electrons spin around the nucleus in an orbit.

The energy differences

between these orbits

can be used to explain

the various colors of light

emitted and absorbed

by gaseous elements.

henry moseley 1914 british physicist
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.
emission spectra
a

Energy ®

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

M band

K band

L band

development of the periodic table
Atomic

Inverse

Ka

Element

Mass

Number

Sqrt(Ka)

(Å)

Li

6.94

3

226.6

0.066

Be

9.01

4

110.7

0.095

B

10.81

5

66.3

0.123

C

12.00

6

43.6

0.151

N

14.01

7

31.0

0.180

O

16.00

8

23.3

0.207

Development of the Periodic Table
slide14
Ka Radiation of Light Weight Elements

2

R

= 0.9951

0.25

0.20

0.15

1/sqrt(Ka)

0.10

0.05

0.00

5

10

15

20

Mass (amu)

slide15
Integer Relationship of Ka Radiation

2

R

= 1

0.25

0.20

0.15

1/sqrt(Ka)

0.10

0.05

0.00

2

4

6

8

10

Integers

Atomic Number

erwin schrodinger 1926 austrian physicist
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.
james chadwick 1932 british physicist
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.
protons neutrons and electrons
charge

(protons & electrons)

19

F

9

mass number

protons & neutrons

atomic number

(protons)

Protons, Neutrons and Electrons

Fluorine atom

How many protons, neutrons and electrons

are in a fluorine atom?

protons neutrons and electrons19
charge

(protons & electrons)

mass number

protons & neutrons

atomic number

(protons)

Protons, Neutrons and Electrons

Chloride ion

37

Cl–

17

How many protons, neutrons and electrons

are in a chloride ion?

protons neutrons and electrons20
Protons, Neutrons and Electrons

Aluminum ion

27

Al3+

13

How many protons, neutrons and electrons

are in an aluminum ion?

using the periodic table
Using the Periodic Table
  • Monatomic ions (ions containing only one atom) often have a charge that can be derived directly from the periodic table.
1 ions
H

O

Li

Be

F

Cl

Na

S

Mg

Al

Ca

Br

K

Cr

Fe

Ni

Cu

Zn

Ti

Mn

As

Co

Sr

I

Rb

Pd

Ag

Cd

Sn

Sb

Pb

Bi

Hg

Cs

Ba

Pt

Tl

Au

+1 ions
2 ions
H

O

Li

Be

F

Cl

Na

S

Mg

Al

Ca

Br

K

Cr

Fe

Ni

Cu

Zn

Ti

Mn

As

Co

Sr

I

Rb

Pd

Ag

Cd

Sn

Sb

Pb

Bi

Hg

Cs

Ba

Pt

Tl

Au

+2 ions
3 ions
H

O

Li

Be

F

Cl

Na

S

Mg

Al

Ca

Br

K

Cr

Fe

Ni

Cu

Zn

Ti

Mn

As

Co

Sr

I

Rb

Pd

Ag

Cd

Sn

Sb

Pb

Bi

Hg

Cs

Ba

Pt

Tl

Au

+3 ions
1 ions25
H

O

Li

Be

F

Cl

Na

S

Mg

Al

Ca

Br

K

Cr

Fe

Ni

Cu

Zn

Ti

Mn

As

Co

Sr

I

Rb

Pd

Ag

Cd

Sn

Sb

Pb

Bi

Hg

Cs

Ba

Pt

Tl

Au

-1 ions
coordination compound nomenclature

Coordination Compound Nomenclature

Edward A. Mottel

Department of Chemistry

Rose-Hulman Institute of Technology

coordination compounds
Coordination Compounds
  • Metal ion
    • the central atom
  • Ligand
    • atom, ion or molecule bound to the metal

The nomenclature of a salt and

a coordination compound

are different.

salt nomenclature
Salt Nomenclature

Fe3+ ion

requires 3 Cl–

FeCl3

iron(III) chloride

Salt (ionic) nomenclature only indicates

the stoichiometry of the compound.

coordination compound nomenclature30
3-

Cl

Cl

Cl

Fe

Cl

Cl

Cl

Coordination Compound Nomenclature

Coordination compound nomenclature

communicates the environment of the central ion.

hexachloroferrate(III) ion

the iron ion is coordinated

to six chloride ligands

coordination compound nomenclature31
H

H

3+

H

O

H

O

O

H

H

Fe

H

H

O

O

O

H

H

H

H

Coordination Compound Nomenclature

Coordination compound nomenclature

communicates the environment of the central ion.

hexaaquairon(III) ion

the iron ion is coordinated

to six water ligands

nomenclature of inorganic coordination compounds
Nomenclature of Inorganic Coordination Compounds
  • Cation/anion sequence
  • Ligand names
  • Cationic/anionic complexes
  • Alphabetical sequencing
  • Brackets
name each of the following
Name each of the following

[Cu(NH3)2Cl2]

diamminedichlorocopper(II)

[Cu(NH3)4]2+

tetramminecopper(II) ion

[CuCl4]2–

tetrachlorocuprate(II) ion

nomenclature of inorganic coordination compounds34
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?
cathode ray tube37
+

-

Cathode Ray Tube

Heated cathodes

emitted cathode "rays"

Deflected by either

magnetic or electric fields

J.J. Thomson, 1897

photoelectric effect38
-

+

Photoelectric Effect

Albert Einstein (1905)German Physicist

Interpreted the

Photoelectric Effect

Confirmed that

light is corpuscular

(possess particle-like properties)

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