1.3 Energy Levels & Emission Spectra

What is a quantum of energy?

The smallest fixed amount of energy that can be absorbed or emitted by an electron during a transition between energy levels.

What does “quantised energy levels” mean?

Electrons can only exist in fixed energy levels, not in between them.

What is a ground state electron?

An electron in the lowest possible energy level of an atom (most stable state).

What is an excited state electron?

An electron that has absorbed energy and moved to a higher energy level.

What happens when an excited electron falls back to a lower energy level?

It releases energy as electromagnetic radiation (light).

What is the relationship between energy difference and frequency?

ΔE = hν
Where ΔE = energy change, h = Planck’s constant, ν = frequency.

What is Planck’s constant?

A constant (6.63 × 10⁻³⁴ J s) used in calculating energy of radiation emitted or absorbed.

What are principal energy levels?

Fixed energy levels in atoms (also called shells), labelled n = 1, 2, 3, etc.

What does n = 1 represent?

The energy level closest to the nucleus (lowest energy level).

What is an emission spectrum?

A spectrum made of separate lines of light produced when electrons fall from higher to lower energy levels.

Why are emission spectra made of lines (not continuous)?

Because electrons only move between fixed energy levels, releasing specific amounts of energy.

What is the convergence limit?

The point in an emission spectrum where lines get closer together, representing transitions from very high energy levels.

What happens at the convergence limit?

The electron has enough energy to completely escape the atom, forming an ion.

What is the Lyman series?

Emission lines produced when electrons fall to n = 1 (ultraviolet region).

What is the Balmer series?

Emission lines produced when electrons fall to n = 2 (visible light region).

What is the Bohr model of the atom?

A model where electrons orbit the nucleus in fixed energy levels and can move between them by absorbing or emitting energy.

Why do emission lines get closer together at higher frequencies?

Because energy levels become closer together further from the nucleus.

What evidence do emission spectra give?

They show that electrons exist in discrete (fixed) energy levels.

What happens if an electron absorbs too much energy?

It can leave the atom completely, forming an ion.