C.A. Coulson(1910 – 1974)

Linus Pauling(1901 – 1994)

Edward Frankland (1825 1899)

Group 5A Elements

When the formulae of inorganic chemical compounds are considered, even a superficial observer is impressed with the general symmetry of their construction. The compounds of nitrogen, phosphorus, antimony, and arsenic, especially, exhibit the tendency of these elements to form compounds containing 3 or 5 atoms of other elements; and it is in these proportions that their affinities are best satisfied: thus in the ternal group we have: NO3, NH3, NI3, NS3, PO3, PH3, PCl3, SbO3, SbH3, SbCl3, AsO3, AsH3, AsCl3, etc.: and in the five-atom group, NO5, NH4O, NH4I, PO5, PH4I, etc. Without offering any hypothesis regarding the cause of this symmetrical grouping of atoms, it is sufficiently evident from the examples just given, that such a tendency or law prevails, and that, no matter what the character of the uniting atoms may be, the combining power of the attracting element, if I may be allowed the term, is always satisfied by the same number of these atoms.

Phil. Trans. Royal Soc.1852

Richard Abegg (1869 -1910)

Abegg’s RuleThe difference between the maximum positive and negative valence of an element is frequently eight.

Nature of LightIsaac Newton (1643- 1727) Christiaan Huygens (1629 – 1695)

Properties of Waves

Reflection Refraction

Diffraction

Interference

Properties of Light

Reflection Refraction

Reflection of Light Corpuscles Refraction of Light Corpuscles

Huygen Construction for Reflection

Huygen Construction for Refraction

Huygen’s Construction

Young’s Double Slit ExperimentThomas Young (1773 – 1829)

Laser Source for Double Slit Experiment

Interpretation of the Double Slit Results

Fresnel’s DotAugustin Jean Fresnel (1788 – 1827)

Simeon Poisson (1781 – 1840)

Maxwell’s EquationsJames Clerk Maxwell (1831 – 1879)

Electromagnetic Radiation

Heinrich Hertz (1857 – 1894)

Light is a Wave

Blackbody Radiation

Cavities as Blackbodies

http://mediaserve.nmt.edu/portal/app/EODILecturePortal.html

http://breeze.nmt.edu/st589dchemnatblackbody/

The Ultraviolet Catastrophe

Lord Rayleigh James Jeans

After a few weeks of the most strenuouslabor of my life, the darkness lifted anda new, unimagined prospect began to dawn.

Max Planck (1858 – 1947)

Photoelectric Effect

Albert Einstein (1879 – 1955) Robert Millikan (1868 - 1953)

Einstein’s equation was a bold prediction,for at that time there was no evidence thatPlanck’s constant had any applicability outside of blackbody radiation and therewere no experimental data on the [kineticenergy] as a function of frequency. Physics by Paul A. Tipler

Millikan’s Photoelectric Data

The Double Slit Experiment Revisited

Light is a Particle