DB

Electrons

Electrons' Locations in an Atom

Energy States/Levels of Electrons

  • Electrons orbit the nucleus in specific energy levels (n).

  • The larger and further away the energy level from the nucleus, the more energy the electrons in that level have.

  • Energy levels are given numbers called quantum numbers.

  • Energy level 1 (closest to the nucleus) is quantum #1.

  • There are 7 energy levels.

  • Electrons are typically in their ground state.

  • If energy is added, electrons go up a level (or more) to their excited state.

Quanta

  • The amount of energy released or absorbed by an atom when energized.

  • When electrons return to their ground state, they release the extra energy and give off colored light.

  • The amount of energy released can be captured with an atomic spectrum.

Atomic Spectrum

  • Energy absorbed equals the energy released by the electrons as light when returning to the ground state.

  • The light given off corresponds with a wavelength, which is color (ROYGBIV).

    • Red light indicates higher energy.

    • Violet light indicates lower energy.

  • The more energy received, the more light is given off.

Electron Location within Energy Levels

  • Within the energy levels are sublevels.

  • There are 4 types of sublevels.

  • Each sublevel is given a letter, which corresponds to a specific shape.

  • The energy levels are given numbers (1, 2, 3…). Within each energy level, there may be several sublevels with different shapes and different orbitals.

Atomic Orbitals

  • Places where electrons are likely to be found (high probability of electrons there) within a sublevel.

  • Each sublevel has a different number of orbitals.

Sublevels Summary Table

Sublevel

Shape

Energy Levels Found In

# Orbitals

Max # Electrons per Orbital

Max Total Electrons

S

Spherical

1-7

1

2

2

P

Dumbbell

2-7

3

2

6

D

Clover Leaf

3-6

5

2

10

F

Complicated

4-5

7

2

14

Electron Configurations

A way to describe how electrons are arranged in an atom.

Principles for Electron Configuration

  1. Aufbau Principle: Electrons fill the orbitals of lowest energy (smaller # first).

  2. Hund's Rule: Electrons enter each orbital in a sublevel before pairing up.

    • Analogy: Imagine a school bus; empty bus seats get taken before people start to pair up.

  3. Pauli Exclusion Principle: Electrons in the same orbital must have opposite spin.

    • Example: One arrow must be pointing up and the other pointing down.

Orbital Notation

  • Shows how electrons occupy sublevels.

  • Each orbital is represented by a box or line.

  • Each line can hold 0, 1, or 2 arrows (representing electrons).

Noble Gas Electron Configuration

  • A shortened version of the electron configuration.

  • Noble gases are Group 18 elements.

  • Includes the previous noble gas, which represents all orbitals up to that point.

  • Shows the outermost level of electrons.