Quiz on Atomic Structure

What did Dalton propose in his atomic theory?

• Atoms are made of protons and neutrons only

• Atoms can be created and destroyed

• All matter consists of tiny particles called atoms

• Atoms are the largest building blocks of matter

Answer explanation

Dalton's atomic theory states that all matter is composed of tiny particles called atoms, which are indivisible and fundamental to the structure of matter. This choice accurately reflects his key proposal.

What model did Thomson develop?

• Planetary model

• Plum pudding model

• Quantum model

• Nuclear model

Answer explanation

Thomson developed the plum pudding model, which proposed that atoms are composed of a positively charged 'pudding' with negatively charged 'plums' (electrons) embedded within it. This model was an early attempt to describe atomic structure.

What did Rutherford's gold foil experiment reveal?

• Atoms are made of empty space

• Presence of a dense nucleus

• Atoms are indivisible

• Electrons are negatively charged

Answer explanation

Rutherford's gold foil experiment demonstrated that most of an atom is empty space, but it also revealed the presence of a dense nucleus at the center, which contains most of the atom's mass.

What is the main feature of Bohr's atomic model?

• Electrons are located in a cloud

• Electrons have no defined paths

• Electrons are randomly distributed

• Electrons are in fixed orbits

Answer explanation

Bohr's atomic model states that electrons move in fixed orbits around the nucleus, each with a specific energy level. This contrasts with other models where electrons are described as being in clouds or having no defined paths.

What is a weakness of Bohr's atomic model?

• Explains the hydrogen spectrum

• Describes electron orbits accurately

• Cannot explain spectra of multi-electron atoms

• Accounts for the dual nature of electrons

Answer explanation

A key weakness of Bohr's atomic model is that it cannot explain the spectra of multi-electron atoms, as it was primarily designed for hydrogen, which has only one electron.

What does the Lyman series correspond to?

• Transitions to n=1

• Transitions to n=2

• Transitions to n=4

• Transitions to n=3

Answer explanation

The Lyman series corresponds to transitions of electrons in hydrogen atoms falling to the n=1 energy level. This series is in the ultraviolet region of the spectrum, making 'Transitions to n=1' the correct choice.

What is the energy of an electron in the ground state of hydrogen?

• 2.18 x 10^-18 J

• 1.09 x 10^-18 J

• 0 J

• 4.36 x 10^-18 J

Answer explanation

The energy of an electron in the ground state of hydrogen is given by the formula E = -13.6 eV, which converts to approximately 2.18 x 10^-18 J. Thus, the correct answer is 2.18 x 10^-18 J.

What is emitted when an electron falls from a higher to a lower energy level?

• A proton

• An ion

• A photon

• A neutron

Answer explanation

When an electron transitions from a higher to a lower energy level, it releases energy in the form of a photon. This process is fundamental in quantum mechanics and is responsible for the emission of light in various phenomena.

What is the relationship between energy and frequency according to Planck?

• Energy is directly proportional to frequency

• Energy is inversely proportional to frequency

• Energy is equal to frequency

• Energy is independent of frequency

Answer explanation

According to Planck's equation, energy (E) is directly proportional to frequency (ν) with the relationship E = hν, where h is Planck's constant. Thus, as frequency increases, energy increases.

What does the Rydberg equation calculate?

• Ionization energy

• Wavelength of emitted light

• Mass of an electron

• Charge of a proton

Answer explanation

The Rydberg equation calculates the wavelengths of emitted light from hydrogen atoms when electrons transition between energy levels, making 'Wavelength of emitted light' the correct choice.