Bohr's Atomic Model and Spectral Lines

Who did Niels Bohr work with to improve the atomic model?

He worked with Ernest Rutherford.

What method did Bohr use to study atoms?

He used spectroscopy to analyze spectral lines from heated gases.

What two things couldn’t Rutherford’s model explain?

Why electrons don’t spiral into the nucleus,

Why atoms emit only specific colours.

What idea from Max Planck did Bohr use?

That energy is quantized (comes in fixed amounts).

According to Bohr, where can electrons exist?

Only at specific energy levels.

What causes spectral lines in Bohr’s model?

Energy released when electrons fall from a higher to a lower energy level.

What happens when energy is added to an atom?

Electrons jump from the ground state to an excited state.

What happens when an excited electron releases a photon?

It falls back to its ground state.

What was Bohr’s First Postulate?

The orbits of electrons are stationary states.  Electrons do not emit energy in these stationary states.

What was Bohr’s Second Postulate?

Electrons gain or lose energy only when moving between stationary states.

In Bohr’s model, what do orbits actually represent?

The energy states of electrons, not orbital levels.

Why does hydrogen show only certain spectral colours?

Because only certain energy transitions are allowed (quantized energy).

What determines how high an electron jumps?

The amount of energy added

What happens when electrons fall back down energy levels?

They release photons of light.

How does the size of an electron’s fall affect the light’s energy?

Small falls give low energy light; large falls give high energy light.

Which spectral series produces infrared light?

The Paschen series (lowest energy).

Which spectral series produces visible light?

The Balmer series.

Which spectral series produces ultraviolet light?

The Lyman series (highest energy).

Why do higher jumps need more energy?

Because electrons closer to the nucleus have stronger attraction.

Why does Bohr’s model only work for hydrogen?

It’s too simple to explain the small variations in complex atoms.