Arrangement of electrons in an atom

Who was the first scientist to provide a picture of the arrangement of the electrons in an atom?

Niels Bohr

How is a continuous spectrum formed?

By shining white light through a prism and viewing it on a screen.

What is an emission line spectrum?

A spectrum with a black background and colored lines on it.

What does Bohr's Theory state about electrons?

Electrons revolve around the nucleus in fixed paths called orbits without gaining or losing energy when in these orbits.

What happens to an electron when it absorbs energy according to Bohr's Theory?

It jumps to a higher energy level, known as the excited state.

Why do electrons not remain in the excited state?

Because they are unstable and must return to their original ground state.

Define the energy level.

The fixed energy value that an electron in an atom may have.

Define ground state.

The state of an atom in which the electrons occupy the lowest available energy levels.

Define excited state.

The state of an atom in which the electrons occupy higher energy levels than those available in the ground state.

Where is the Lyman series located?

In the ultraviolet region, when an electron falls to the n=1 energy level.

Where is the Paschen series located?

In the infrared region, when an electron falls to the n=3 energy level.

What is the name of the series of lines in the visible spectrum?

The Balmer series, when the electron falls to the n=2 energy level.

In the formula E=hf, what do h and f stand for?

h = Planck's constant, f = frequency of light.

What is Atomic Absorption Spectrometry?

A technique where white light is passed through a gas sample of an element before going through a prism, discovering dark lines in the continuous spectrum.

Give 2 uses for Emission line spectrum and Atomic Absorption Spectrometry.

Emission: identification of elements and used in fireworks; Absorption: identification of elements and finding the concentration of elements.

What are energy sublevels?

Subdivisions of a main energy level consisting of one or more orbitals of the same energy.

Why does the 4s sublevel come before the 3d sublevel?

Because it takes more energy to get into the 3d sublevel.

Who discovered that electrons travel in a wave motion?

De Broglie.

What is Heisenberg’s Uncertainty Principle?

It states that it is impossible to measure both the velocity and position of an atom at the same time.

Give 3 limitations of Bohr’s theory.

It only works for hydrogen, did not consider the wave nature of electrons, and did not address sublevels.

Define an atomic orbital.

A region in space where there is a high probability of finding an electron.

What shape is the S orbital?

Spherical.

What shape are the P orbitals?

Dumbbell shape.

How were energy sublevels discovered?

Scientists found that the emission lines were not singular, but some were made of multiple lines.