1. Electron Arrangement or Electron Configuration

2. Electron Arrangement/Configuration modern chemistry changed some of Bohr’s ideas each energy level is divided into sublevels which are called orbitals orbitals are s, p, d, & f and all have various shapes Orbital  the region of high probability of finding an electron

3. each orbital can hold only two electrons s orbitals are spherical in shape  compare the 1s orbital to the 2s orbital p orbitals are dumbbell shaped  specifically, there are 3 p orbitals differentiated by the labels p x, p y, & p z For example, 3s 2,3 = energy level s = type of orbital 2 = number of electrons (in that orbital)

4. s and p orbitals

7. Sublevel s is lowest in energy followed by p, then d, then f s sublevel can hold a maximum of 2 electrons p sublevel can hold a maximum of 6 electrons d sublevel can hold a maximum of 10 electrons f sublevel can hold a maximum of 14 electrons

8. Some energy levels do not have all the sublevels 1 st energy level – s orbital only 1s 2 nd energy level – s & p orbitals 2s & 2p 3 rd energy level – s, p, & d orbitals 3s, 3p, &3d 4 th energy level – s, p, d, & f orbitals 4s, 4p, 4d, & 4f

9. The process of organizing electrons in atoms from the orbital with the lowest energy to the orbital with the highest energy is called electron configuration/arrangement. Electrons are not organized or “build up” in order of energy level and sublevels i.e. 4s come first then 3d

10. Use the following diagram to help remember the order in which orbitals fill: 7s7p 6s6p6d 5s5p5d5f 4s4p4d4f 3s3p3d 2s2p 1s

11. Examples: Write the electron configurations for the following: (always determine the total number of electrons involved then use the helpful tool to write out each orbital in order of building up) H O K

12. Make Note: The periodic table is divided according to the filling order of sublevels Can relate a specific sublevel to a part of a row in the periodic table Creates trends in how elements react

13. Periodic Table