Chapter 7 - Quantum Theory of Atoms

Crest

Place of MAX disturbance

Trough

Place of MIN disturbance

Node

Place of 0 disturbance

Amplitude

MAX output of wave measured from center

Wavelength

distance from crest to crest or trough to trough (measured in m, symbol λ)

Frequency

How many waves pass by per second (s^-1 or Hz, symbol v)

Speed of wave equation

FREQUENCY x WAVELENGTH

s^-1 x m = m/s

Electromagnetic Spectrum

Light waves…

1) travel at speed of light

2) made of electromagnetic fields that “wave” at e/o

3) C = vλ (speed)

Particles of light are called

photons

Energy of photon equation

E = hv

E → energy of photon

h → 6.626 × 10^-34 Js

E = hc/λ

v = c/λ

Explain the Bohr Model of an Atom

Electron gains energy → jumps to an excited state for higher energy level

Electron loses energy → no “excited state” because it releases photon of light (fall back down)

E_n = -2.18 × 10^-18 J / n²

r_n(radius of electron’s orbit at level n) = (52.9pm)n²

Wavelength equation for photon

λ = 91.1 nm / (1/n² _f - 1/n² _i )

nf = energy level final

ni = energy level initial

What’s ground state

Arrangement of electrons in atom where all are in lowest possible energy level

What’s excited state

Any arrangement of electrons in an atom where 1+ electrons gained energy and reach higher energy levels

Quantum mechanical model of atom

• Electrons act like waves λ

• “Electron density” is ψ² (probability of where electrons are)

• Electrons exist in orbitals (regions of high probability)

• Orbitals described in 4 quantum #s (n, l, m_l , and m_s )