Electron Configuration Guided Notes How to write electron configurations, orbital notations, and Noble Gas configurations

Properties of Electrons Electrons don’t behave like normal particles. They also act like waves. Because they act like waves, their exact location around the nucleus cannot be calculated. Bohr’s examination of the hydrogen atom also found that electrons were only allowed to have specific amounts of energy. Other energies are forbidden. The allowed energy of an electron around an atom is called a quantum. Because we can’t see electrons in specific orbits, electrons are contained in orbitals around atoms. Orbitals are calculated regions of space where electrons can exist. Each orbital can hold two electrons. The quanta of energy that electrons can have refer to the energy levels of the atom. The more energy an electron has, the further from the nucleus it is.

Orbitals Orbitals have four sublevels: s, p, d, and f. s Orbital sublevel What energy levels can they exist at? How many types of these orbitals can exist at any energy level? What is the maximum number of electrons that can be held by these orbitals at any energy level? s 1st and higher 1 2 p 2nd and higher 3 6 d 3rd and higher 5 10 f 4th and higher 7 14

Rules for filling orbitals There are three rules for filling orbitals. Aufbau Principle: Electrons always fill the lowest energy levels first. Electrons start at the bottom and work their way up. This also implies that electrons fill orbitals the same way every time. Pauli Exclusion Principle: No two electrons with the same energy characteristics can occupy an orbital at the same time. One electron must be spin up and the other electron must be spin down. Hund’s Rule: When filling multiple orbitals of the same sublevel (p, d, and f), electrons half-fill the sublevel first before pairing electrons.

Orbital Energy

Order for Filling Orbitals 7s 7p 7d 7f 6s 6p 6d 6f 5s 5p 5d 5f 4s 4p 4d 4f 3s 3p 3d 2s 2p 1s

Connections to the Periodic Table The first two columns of the periodic table are the s-block. The last six columns of the periodic table are the p-block. The middle ten columns of the periodic table are the d-block. Remember that d-block elements fill one energy level late! After 3p is filled, 4s is filled, then 3d is filled, and then 4p is filled. The bottom two rows of the periodic table are the f-block. Remember that f-block elements fill two energy levels late! After 5p is filled, 6s is filled, then 4f is filled, then 5d is filled, then 6p is filled.

Color-code and label your periodic table!