1. Warm Up9-10-15 1. Electrons are responsible for the atomic _____ (mass or volume) 2. List the number of protons, electrons and neutrons for the following elements: B, Ag, & K-40 3. 3. Which of the following are isotopes? Homework WS unit 2-4 Sept 14 - Quiz unit 2 Sept 18 - Online HW unit 2 Agenda Turn in Penny Lab Notes Unit 2-4 WS unit 2-4 Online HW 4

2. Unit 2-4 Electron Properties

3. Electron Behavior Electrons exhibit properties of both particles and waves Electrons exhibit properties of both particles and waves Electrons are located in orbitals, that correspond to specific energy level Electrons are located in orbitals, that correspond to specific energy level Electrons can be considered waves confined to the space around a nucleus Electrons can be considered waves confined to the space around a nucleus

4. Electromagnetic Spectrum

5. Light Emission Electron energy levels are determined through an element’s emission spectrum When electrons absorb energy, they change energy levels within the atom

6. Light Emission However, they are unstable in this excited state Electrons move back to a more stable ground state, by emitting energy in the form of light (photon) http://micro.magnet.fsu.edu/primer/ java/fluorescence/exciteemit/index. html http://micro.magnet.fsu.edu/primer/ java/fluorescence/exciteemit/index. html

7. Light Emission The photon (energy packet) that is emitted will have a different wavelength (color) depending on the amount of energy that was released The photon (energy packet) that is emitted will have a different wavelength (color) depending on the amount of energy that was released Examples light spectrum: Hydrogen and Iron Examples light spectrum: Hydrogen and Iron

8. Light Emission Each element has a different number and arrangement of electrons Each element has a different number and arrangement of electrons Therefore, elements can be identified based on their emission spectrum Therefore, elements can be identified based on their emission spectrum This is how we know that the sun is composed of hydrogen and helium This is how we know that the sun is composed of hydrogen and helium

9. Quantum Model Quantum model - Electrons exist at particular energy levels in their orbitals Quantum model - Electrons exist at particular energy levels in their orbitals

10. Quantum Model Electron configurations - indicate the arrangements of the electrons within the atom Electron configurations - indicate the arrangements of the electrons within the atom -These are written using quantum numbers -Used to pinpoint where an electron is probably located

11. Assignments Check grades Check grades Notes summary Notes summary Worksheet unit 2-4 (#1-17) need my initial before class is over Worksheet unit 2-4 (#1-17) need my initial before class is over Online HW unit 2 Online HW unit 2