Chapter 4 in Depth

Page 1

When Light Behaves as a Wave

Speed of Light Constant = Wavelength x Frequency

Equation: c = λ • ν

c - speed of light - meters per second (m/s) - 3.00x10^8 m/s

λ - wavelength - meters

v - frequency - Hz or 1/s or s^-1

Used when light is seen as a wave

When Light Behaves as a Particle

Energy = Planck's Constant x Frequency

Equation: E = h • v

E - energy - J (joules)

h = 6.626x10^-34 J • seconds

f (or v) = Hz

Used when light is seen as a particle ("photon")

Hydrogen-Atom Emission-Line Spectrum

shows different types of electromagnetic radiation emitted as electrons travel from higher to lower energy levels

(UV radiation, Visible light, Infrared radiation)

1. Electron transitions to ground sate - corresponds to UV radiation

(highest energy, high frequency, short wavelength)

2. Electron transitions to n=2 - corresponds to visible light

(violet is highest energy, red is lowest energy)

3. Electron transitions to n=3 corresponds to infrared radiation

(lowest energy of all three emissions, low frequency, longest wavelength)

Atomic Orbitals and Quantum Numbers

In the Bohr atomic model, electrons of increasing energy occupy orbits farther and farther from the nucleus

Quantum numbers are used to completely describe orbitals

Quantum numbers - specify the properties of atomic orbitals and the properties of electrons in orbitals.

Quantum Numbers

1. Bohr Model of the Hydrogen atom - e- is in orbit of the nucleus (the electron is in orbit around the nucleus at a certain distance) INCORRECT

2. Quantum Mechanics Model of the Hydrogen atom - e- is in orbital (we don't know exactly where, instead it is in a region of space where is it most likely to be found) BEST WAY TO EXPLAIN ELECTRONS IN ORBITALS

Principal quantum number (n)

-tells us the main energy level/shell

-as n increases, energy increases as well as distance from the nucleus

Angular momentum quantum number (l)

-tells us the shape of the orbital

-values for l depend on n

Magnetic quantum number

-tells us the orientation of the orbital

-values of this depend on l

Spin Quantum Number

-