Chemistry Notes: Electromagnetic Radiation

Electromagnetic Radiation: is a form of energy that exhibits wavelike behavior as it travels through space at the same speed Properties of Light

Wavelength ( λ ) is the distance between corresponding points on adjacent waves. Frequency ( ν ) is defined as the number of waves that pass a given point in a specific time Frequency and wavelength are inversely proportional Properties of Light

Wavelength and Frequency

Frequency and wavelength are mathematically related to each other: c = λν c = is the speed of light = 3.0 x 10 8 m/s λ = is the wavelength (m) ν= is the frequency (Hz)

**Remember c is a constant = 3.0 x 10 8 m/s 1. A wave has a frequency of 2 x Hz. What is the wavelength? Practice using the equation c = λν

2. A certain microwave has a wavelength of meters. Calculate the frequency of this microwave. Practice

3. A low-frequency radio wave has a frequency of 250,000Hz. What is the wavelength of this radiowave? Practice

A Quantum of energy is the minimum energy that can be lost or gained by an atom. E= h v E = energy in Joules h= planks constant, x J s v= frenquency Quantum Energy

1.Determine the energy in joules of a photon whose frequency is 3.55 x Hz. Practice

1922 -Solved the problem of hydrogen’s line emission spectrum. Proposed: Hydrogen only released photons at certain energy levels Electrons are in FIXED energy levels Neil Bohr

Ground State vs. Excited State e-e- e-e- Ground state Excited state Electrons absorb energy and move to an excited state. Ground state – the lowest electron energy level in an atom Excited state- A state at which an atom has higher potential energy than it’s ground state

Bohr Model Electrons return to ground state and emit energy in the form of light (photon). Energy of the photon depends on the difference in energy levels nucleus Red GreenBlue Violet Low EnergyHigh Energy