1. Ch 4 Arrangement of Electrons in Atoms 4
Ch 4 Arrangement of Electrons in Atoms 4.1 The Development of a New Atomic Model
Electromagnetic radiation: visible light, x-rays, UV, infrared, Gamma, radio, microwaves
Electromagnetic spectrum

2. Wavelength: distance between corresponding points
Frequency: # waves that pass a given point
Photoelectric effect: when light strikes a metal, e- are released
Quantum: E that can be gained/lost by an e-
E=hv
E is Energy
v is frequency s-1
h is constant 6.626x10-34 J.s
Photon has 0 mass and carries quantum of E

3. Ground state: lowest E
Excited state: higher E potential
Emission-line spectrum: see bands of colors
Continuous spectrum: ex rainbow, see range of frequencies

4. Bohr’s Atomic Model e- circled nucleus on paths or orbitals
Lowest energy state near nucleus
When e- gets excited to moved up Energy level, called absorption
When e- falls to lower Energy level, photon is emitted, called emission

5. 4.2 The Quantum Model of the Atom
De Brogile
Light behaves both as a wave and particle
e- have wavelike properties
Diffraction: waves interfere; interference: waves overlap
Heisenberg
Heisenberg uncertainty principle: cannot know both position and velocity at same time
Schrodinger
Describes mathematically wave properties of e-
quantum numbers: orbital
Principal quantum number: main energy level; n 1-6
Angular momentum quantum number: shape/ s,p,d orbital
Magnetic quantum number: 3-D/ x,y,z planes
Spin quantum number: e- spin

6. Angular momentum quantum number:
Shape of orbital
Magnetic quantum number: m
Orientation of orbital around nucleus

7. Number of orbitals in main E level increases with value of n
Spin quantum number:
+ ½ or – ½
2 e- per orbital
The e- spin oppositely

8. 4.3 Electron Configurations
Aufbau Principle: fill lower energy levels first
Pauli Exclusion Principle: no 2 e- can have same set of quantum numbers
Hund’s Rule: fill all before pairing orbitals

9. Orbital Notation: arrow diagram
Electron-configuration: writing it all out
Noble-gas: [noble gas] with rest of e- written out
Final Entry: exact location

10. Argon, Ar
Potassium, K