Atomic Theory Test Review

How did Thomson's model describe the positively charged part of the atom?

• discrete particles that are identical to electrons but having an opposite charge

• discrete particles that are much larger than the electron and having an opposite charge

• a uniform mass surrounding the electrons with a total positive charge equal to the total negative charges of the electrons

• a uniform mass surrounding the electrons with individual positive charges that overlap each electron

In his model of the atom, Bohr proposed that electrons move at fixed distances from the nucleus and that the energy of the electron is related to its orbit. What discovery contributed to the development of this atomic model?

• Electrons can flow freely through metals making metals good conductors.

• Elements have characteristic wavelengths of light emission and absorption.

• Noble gas elements are much less reactive than most other elements.

• Electrons exhibit properties of both particles and waves.

What conclusion did Rutherford make based on the observation that, while bombarding gold foil, some of the particles bounced back?

• The alpha particles had insufficient mass to pass through the foil.

• The alpha particles met a force with a large volume and a positive charge

• The alpha particles met a force with a small volume and a positive charge.

• The atom contained electrons that orbited the nucleus like the Sun.

In the electron cloud model of the atom, what does the cloud represent?

• the limits of the electron location

• the probability of the electron location

• the average distance between the electron and the nucleus

• the minimum distance between the electron and the nucleus

Which of the following BEST describes Thomson’s contribution to the atomic theory?

• Electrons exhibit both particle and wavelike behavior.

• Electrons exert repulsive forces on one another.

• Electrons and equal numbers of positive charges exist.

• Electrons absorb discrete amounts of energy.

In this model, what do the circles numbered 1, 2, and 3 represent?

• the locations of the electrons

• B the exact path of an electron orbit

• the number and locations of electrons in the atom

• the allowed energy levels of the electron of the atom

In 1909, scientists fired the nuclei of helium atoms at a sheet of gold foil only a few atoms thick. To their surprise, some particles bounced back from the foil instead of passing through it. To explain the data, Ernest Rutherford proposed that most of each atom is empty space, with a small dense nucleus at the center. Why did the small dense nucleus make the Alpha-particles bounce back?

• The α-particles are positive just like the protons making the opposite charges repel eachother.

• The α-particles are negative just like the protons making the opposite charges repel eachother.

• α-particles can not pass through gold

• All particles will pass through because all of the atom is empty space.

Why was the neutron hard to detect by scientists?

• It's very large

• It has a negative charge

• It has a positive charge

• It has a neutral charge

In the late 1800s, experiments using cathode ray tubes led to the discovery of the —

• Proton

• Positron

• Electron

• neutron

Put the historical developments leading to the modern model of the atom in chronological order.

• The atom is a hard sphere

• Most of the atom is empty space

• Electrons exist in orbitals outside the nucleus