Download WAVE MECHANICS AND QUANTUM NUMBERS

WAVE MECHANICS AND QUANTUM NUMBERS
A. Electrons as Waves
1. Louis de Broglie 1924- electrons are considered waves confined to the space around a
nucleus.
2. supported by the facts that electrons undergo diffraction and interference
3. Werner Heisenberg 1927- Heisenberg Uncertainty Principle: it is impossible to
simultaneously identify the position and velocity of an electron, or any particle.
4. wave mechanics looks to suggest the locations of electrons
5. space orbital- highly probable location where an electron can be found
6. electron cloud- the size and shape of an atom as defined by the electron paths
B. Quantum Theory- describes the wave properties of electrons in a mathematical fashion; it utilizes
quantum numbers that describe the unique energy state of electrons.
1. Erwin Schrödinger 1926- used the new quantum theory to write and solve a mathematical
equation describing the location and energy of an electron in a hydrogen atom.
2. Modern day quantum mechanical model comes from the math solutions to Schrödinger’s
equations. It extended de Broglie’s work by considering the movement of a particle in an
electromagnetic field.
3. Defined quantum numbers
a. principal (n)- most probable distance from the nucleus; Set = (1, 2, 3, 4, 5, 6, 7) with
1 being closest to the nucleus. Most general quantum number.
b. angular momentum/orbital (l)- indicates the shape of the electron path; defined by
values n – 1 for orbital within the energy level, so Set = (0, 1, 2, 3) corresponding to
orbital shapes (s, p, d, f) The determines the possible shapes for that principal
quantum number.
c. magnetic (ml)- indicates the positions about the axes. For the shapes (s, p, d, f) get
positions (1, 3, 5, 7) identified by values of l to –l so Set = (-3, -2, -1, 0, 1, 2, 3).
d. spin (ms)- identifies two fundamental spin states of an electron; Set = (+1/2 and -1/2),
spin up and spin down. This is the most specific quantum number because all other
identify a pair of electrons.