Electrons And Light

1. Electrons And Light

2. Electromagnetic Radiation • Energy that travels as a wave through space • Wavelength –λ – distance between corresponding points on adjacent waves • Frequency – f – waves per second

3. Spectrum • Breakdown of electromagnetic radiation by increasing wavelength • Visible light is one small portion of the electromagnetic spectrum

5. Relationship Between Electrons And Light • When energy is given to an atom, it gives off light • When light is shined on certain metals, they give off electron – Photoelectric effect • By old theory, it doesn’t make sense that they are related – electrons are particles and light is a wave

6. Quantum Theory • Says that light travels in chunks (like particles) that follow the path of a wave • Quantum – finite chunk of energy • Photon – a quantum of light • Since light acts as both a wave and a particle it can interact with electrons • Light has a wave-particle duality

7. Bohr Model • In the atom, electrons exist in quantum energy levels (n levels) • Electrons have the lowest energy when closest to the nucleus • Under resting conditions, the electrons are in the lowest possible energy level called ground state

8. When atom absorbs a quantum of energy, it causes the electron to jump to a higher energy level called the excited state • Excited atom is energetically unstable, so electron will fall back down very rapidly and energy will given off in the same amount as absorbed but now in the form of a photon of light

10. Line Emission Spectrum • Electrons falling to and from different levels produce different colors of light • Since every atom has different numbers of electrons, each produces its own unique color bands of light – line spectrum • Spectroscopy is the process of using the color bands to identify specific atoms

11. Line Spectrum For Hydrogen

12. True or False The distance between two waves is called the frequency.

13. A breakdown of waves by wavelength is called • Electromagnetic Radiation • Spectrum • Visible light • Photoelectric Effect

14. A chunk of energy is called a _________.

15. When electrons are in the lowest energy level possible, they are in • Ground state • Excited state • Main energy level • Orbitals

16. When electrons in the ground state absorb energy, they leap to an ____________ state.

17. When electrons fall back down from the excited state, they release a __________. • chunk of energy • Quantum of energy • Photon of light • Electron

18. True or False The line emission spectrum for every atom is different since every atom has different numbers of electrons.