Agree Learning Outcomes: Topic: P6.1.5 Radiation in and out of atoms Spec link: P Time: 70 mins Recorded Assessment: Review: Present New Knowledge: Agree Learning Outcomes: Describe how electrons are arranged in atoms Describe what happens when atoms absorb and emit EM radiation Apply To Demonstrate: Construct Meaning:

Radiation in and out of atoms Why do some materials glow?

How are electrons in atoms arranged? Electrons are negative, and the nucleus is positive,so why do electrons not spiral into the nucleus? It’s been worked out that electrons can only occupy certain specified energy levels. Different atoms have different energy levels

A simple model Electron has different energy levels: Floors in a building. Lowest is called the Ground State. Higher states are Excited States.

Electrons usually occupy the lowest possible e______ l_____, at the smallest distance from the n_______.

Changing Levels If you add the RIGHT amount of energy to an a_____, the electron will jump up e_____ levels. If the electron drops d____ energy levels, the atom gives up the s_____ amount of energy, as a PHOTON (a particle of light)

LIGHT: What Is It? Light Energy Atoms As atoms absorb energy, electrons jump out to a higher energy level. Electrons release light when falling down to the lower energy level. Photons - bundles/packets of energy released when the electrons fall. Light: Stream of Photons A photon that has enough energy can completely remove an electron from an atom. The atom is ionised.

Absorption Spectrum of hydrogen Continuous spectrum Black lines (light absorbed by the atoms of the element)

Every element has a different absorption spectrum He Fe

Emission Lines Every element has a DIFFERENT finger print.

Emission Spectrum of hydrogen Black background Coloured lines (light emitted by the excited atoms) The highest energy photons from a Hydrogen atom are in the Ultraviolet part of the EM spectrum

How do the 2 compare? Write a paragraph comparing the absorption and emission spectrum for Hydrogen

The frequency of radiation emitted depends on the difference in energy of the energy levels. The energy change can take place in one go, or two or more. If there are two changes then the emitted photons will have less energy, lower frequencies and longer wavelengths The largest energy difference is from an energy level just below ionisation. Gamma rays are the highest energy radiation and are emitted from the nuclei

LIGHT: What Is It? Light Energy Atoms As atoms absorb e_____, electrons jump out to a h______ energy l______. Electrons release l_____ when falling d_____ to the lower e_____ level. Photons - bundles/packets of energy released when the e_______ fall. Light: Stream of p_______ A p_______ that has enough e______ can completely remove an e_____ from an atom. The a_____ is ionised.