Dr. S. M. Condren

Dr. S. M. Condren

Electromagnetic Radiation

Electromagnetic wave

• wavelength

• frequency

• amplitude

Dr. S. M. Condren

Black Body Radiation

http://www.cbu.edu/~mcondren/C11599/BBvis.mov

Dr. S. M. Condren

Photoelectric Effect

• the emission of electrons by substances, especially metals, when light falls on their surfaces.

Dr. S. M. Condren

Dr. S. M. Condren

Dr. S. M. Condren

Line Spectrum

A spectrum produced by a luminous gas or vapor and appearing as distinct lines characteristic of the various elements constituting the gas.

Dr. S. M. Condren

Emission Spectrum

The spectrum of bright lines, bands, or continuous radiation characteristic of and determined by a specific emitting substance subjected to a specific kind of excitation.

Dr. S. M. Condren

Ground State

The state of least possible energy in a physical system, as of elementary particles. Also called ground level.

Dr. S. M. Condren

Excited State

Being at an energy level higher than the ground state.

Dr. S. M. Condren

Dr. S. M. Condren

Absorption Spectrum

• Light shinning on a sample causes electrons to be excited from the ground state to an excited state

• wavelengths of that energy are removed from transmitted spectra

Dr. S. M. Condren

Bohr Atom

Dr. S. M. Condren

Line Spectra

Lyman series => ultraviolet

n > 1 ==> n = 1

Balmer series => visible light

n > 2 ==> n = 2

Paschen series => infrared

n > 3 ==> n = 3

Dr. S. M. Condren

Magnetism

• Result of the spin of electrons

• diamagnetism - no unpaired electrons

• paramagnetism - one or more unpaired electrons

• ferromagentism - case of paramagnetism where the substance retains its magnetism

Dr. S. M. Condren

paramagnetic ferromagnetic

Dr. S. M. Condren

Atomic Radius

• increase top to bottom down a group– each additional electron “shell” shields the

outer electrons from the nuclear charge

Zeff = Z - Swhere Zeff => effective nuclear charge

Z => nuclear charge, atomic numberS => shielding constant

Dr. S. M. Condren

Dr. S. M. Condren

Dr. S. M. Condren

Ionization Energy

• energy necessary to remove an electron to form a positive ion

• low value for metals, electrons easily removed

• high value for non-metals, electrons difficult to remove

• increases from lower left corner of periodic table to the upper right corner

Dr. S. M. Condren

Dr. S. M. Condren

Electron Affinity

• energy released when an electron is added to an atom

• same trends as ionization energy, increases from lower left corner to the upper right corner

• metals have low “EA”

• nonmetals have high “EA”