Notes Ch 5 Electron Configuration

 

Wave Characteristics:

Wavelength       λ    greek lambda

      Distance from 1 crest to the next

      Unit is the m

 

Frequency          ν    greek nu

     # of waves that pass a point in  1s

     Unit is s-1 or Hz

 

Speed of light    c  (lower case)

All EM waves/light travels at the same speed 3.0  x 108 m/s

 

Amplitude          A

Height of the wave; indicates amount of energy the wave has

 

Problems: because all EM waves travel at the same speed, you can use the following equation to calculate wavelength or frequency of any wave:

c=λν

 

speed of light=wavelength x frequency

 

3 x 108 m/s = m  ·  Hz

 

If you know λ:       m/s ÷ m = s-1 or Hz

If you know ν:       m/s ÷ Hz = m

 

Do problems # 1-4 p. 121

 

Can you identify a type of EM radiation by its frequency?

 

EM/Visible Light (click to see)

ROY G BIV

Def. Quantum- min. amt. of E that can be gained or lost by an atom. (Max Planck 1900-1901)

Equantum=hv

(E)Energy=(h)plancks constant x (ν)frequency

        h =(6.626 x 10 -34 J·s)

 

Einstein-(1905)light is particles (photons) that behave in wave-like fashion.

Called it “wave-particle duality”

Photon- tiny bundles of energy/light particles

E=hv

Problems # 5-6 on p.124

#5 Answer in Joules (J)

 

Photoelectric Effect-

p. 123-124

 

Neils Bohr- assigned a quantum number (n) to each orbit & calculated the orbit’s radius.

(see table 5-1 p. 127)

 

Bohr’s model of the atom was not completely correct; Others contributed.

 

* electons have a wave-like motion & are restricted to circular orbits of fixed radii. (Louise de Broglie)

 

*it is not possible to know precisely the velocity & position or an electron (at the same time) b/c the act of observing an e- (using a photon of light) changes the position & vel. of the electron. See fig. 5-12 p. 131) (Heisenberg Uncertainty Principle)

 

p. 132 H’s Atomic Orbitals

*orbital boundries are fuzzy/no exact defined size

 

Principal Quantum numbers(n) – as n increases, the e- spends more time farther from the nucleus.

·    n indicates relative sizes & energies of atomic orbitals

·    n specifies the atom’s major energy levels (E levels) called Principal Energy Levels

 

Principal Energy Levels contain energy sublevels (see figures 5-15, 5-16  p. 133)

Study Table 5-2 p. 134 to see Number of orbitals related to sublevels.

 

Section 5.3

Low Energy systems are more stable therefore atoms tend to assume the lowest e- configuration.

 

3 Principles define how e- can be arranged:

 

1.                      Aufbau Principle: each e- occupies the lowest E orbital available; See Fig 5-17 that shows sequience of lowest to highest E orbitals (related to fig 5-19 on p. 138)

 

 

2.                      Pauli Exclusion Principle:  the maximum number of 2 e- may occupy a single atomic orbital but only if the electons have opposite spin

 

3.                      Hund’s Rule:  single e-‘s with the same spin must occupy each equal-energy orbital  (for example 2px, 2py, 2pz) before additional e-‘s with opposite spins can occupy the same orbital.

 

Following the 3 rules (Aufbau, Pauli, & Hund’s) fill in the orbital diagrams and electron configuration notation for the first 20 elements.  Also draw the electron dot diagrams.