Ch. 4.6 Electron Energy Levels

We experience electromagnetic radiation in different forms such as light, the colors of the rainbow or x-rays
Electromagnetic radiation consists of energy particles that move as waves of energy
The distance between the peaks of waves is called the wavelength
High-energy radiation has shorter wavelengths
Low-energy radiation has longer wavelengths

When light from a heated element passes through a prism, it separates into distinct lines of color separated by dark areas called an atomic spectrum
Each element has its own unique atomic spectrum.

The lines in an atomic spectrum are associated with changes in energies of electrons.
In an atom, each electron has a specific energy, known as its energy level, which is assigned:
principal quantum numbers n = 1, n = 2, \ldots
Energy increases as n increases and electrons are farther away from the nucleus
The energy of an electron is quantized- electrons can only have specific energy values
Electrons with the same energy are grouped into the same energy level

Changes in Electron Energy Level

electrons move to a higher energy level when they absorb energy
When electrons fall back to a lower energy level, light is emitted
The energy emitted of absorbed is equal to the differences between the two energy levels

It is the arrangement of electrons that determines the physical and chemical properties of an element

Each energy level contains one or more sublevels
The number of sublevels in energy level is equal to the quantum number n of that energy level
Sublevels are labeled s, p, d, f.
The order of sublevels in an energy level from lowest to highest energy is: s \lt p \lt d \lt f.

Orbitals are three-dimensional volume in which electrons have the highest probability of being found
The s orbitals are shown as spheres
the electron cloud of an s orbital represents the highest probability of finding an s electron
the size of the s orbitals increase because they contain electrons at higher energy levels

There are three p orbitals, starting with n = 2
Each p orbital has 2 lobes, like a balloon tied in the middle and can hold a maximum of 2 electrons.
The three p orbitals are arranged perpendicular to each other along the x, y, and z axes around the nucleus.

A p orbital has two regions of high probability, which gives a “dumbbell” shape.
Each p orbital is aligned along a different axis from the other p orbitals
all 3 p orbitals are shown around the nucleus

The d sublevels contain five d orbitals.
Four of the five d orbitals consist of four lobes that are aligned along or between different axes
one d orbital has two lobes with a donut-shaped ring around its center.

The Pauli exclusion principle states that

Electrons in the same orbital repel each other.
Electrons in the same orbital must have their magnetic spins cancel (they must spin in opposite directions)
An orbital can hold up to two electrons with opposite spins, often depicted with arrows.

s sublevel: one orbital; maximum 2 electrons.
p sublevel: three orbitals; maximum 6 electrons.
d sublevel: five orbitals; maximum 10 electrons.
f sublevel: seven orbitals; maximum 14 electrons.
The maximum number of electrons in each energy level:
- n=1: 2 electrons
- n=2: 8 electrons
- n=3: 18 electrons
- n=4: 32 electrons
Represented as 2, 8, 18, 32 for n = 1, 2, 3, 4 respectively.

Absorption: electrons move to a higher energy level when energy is gained.
Emission: electrons fall to a lower energy level, emitting light.
The energy emitted or absorbed equals the difference between the two energy levels