Electron Configuration - Science Reviewer

**Semi-Finals** **Electron Configuration** - is the arrangement of electrons in an atom. **Key Components:** 1\. Energy levels are numbered starting from 1 (closest to the nucleus) and increasing outward (2,3,4,etc.) -- represents the main energy levels or shells around the nucleus. 2\. Orbitals...

**Semi-Finals** **Electron Configuration** - is the arrangement of electrons in an atom. **Key Components:** 1\. Energy levels are numbered starting from 1 (closest to the nucleus) and increasing outward (2,3,4,etc.) -- represents the main energy levels or shells around the nucleus. 2\. Orbitals (s,p,d,f) -- describe the shape and orientation of the regions where electrons are likely to be found. Electron shell refer to the overall energy level. While orbitals refer to specific regions within that energy level. **Notation:** Electron configuration is typically written in a specific notation: - The **number** represents the [energy level.] - The **letter** represents the type of [orbital (s,p,d,f)] - The **superscript** number represents the [number of electrons in that orbital.] **Memorize the basic list of orbitals:** s= 2 electrons p= 6 electrons d= 10 electrons f= 14 electrons **Aufbau Principle** is a fundamental concept in chemistry and physics that explains how electrons occupy orbitals in an atom. "Aufbau" in German means "building up". [Filling order: ] Electrons fill the lowest energy levels first before moving to higher ones. This is known as the **Aufbau principle.** \- The general order of filling is: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p and so on. Note: 4s orbital is filled before the 3d orbital because it has a lower energy level. **Writing Electron Configuration:** Example: Oxygen -- has an atomic number of 8, meaning it has 8 electrons. Following the Aufbau principle, fill the orbitals: **Oxygen (O):** 8 electrons = 1s^2^ 2s^2^ 2p^4^ **Sodium (Na):** 11 electrons = 1s^2^ 2s^2^ 2p^6^ 3s^1^ **Helium (He):** 2 electrons = 1s^2^ Pauli Exclusion Principle -- states that no two electrons can have the same set of quantum numbers. Hund' rule - states that electrons occupy empty orbitals before pairing up in an orbital. Aufbau principle -- states that electrons occupy the lowest available energy level. **Types of Exam:** Test I- Multiple Choice Test II -- Writing electron configuration Test III -- Short answer essay. **Note: Bring your Periodic table. Study well esp. in writing the electron configuration of an element.**