Unit 2 & 3 Review

Scientists are consistently building on each other’s models. What did Bohr add to the model of the atom?

• That atoms are solid structures and simple building blocks.

• That atoms have protons and electrons stuck together.

• That atoms have orbiting electrons that can jump energy levels.

• That there is an electron cloud around a nucleus.

Which scientist bombarded gold sheets with alpha particles to look at the atom?

• Rutherford

• Bohr

• Einstein

• Planck

Which model of the atom was used as a result of J.J. Thomson's cathode ray experiments?

• Plum pudding model

• Nuclear model

• Planetary model

• Quantum mechanical model

Which model of the atom is based on the mathematical probability of finding the location of an electron?

• Plum pudding model

• Nuclear model

• Planetary model

• Quantum mechanical model

Around the turn of the twentieth century, English physicist J. J. Thomson discovered that cathode rays are streams of negatively charged particles. Because he was able to produce cathode rays using various kinds of metals, Thomson concluded that all atoms must contain these negatively charged particles. From this discovery, to what ultimate conclusion regarding the structure of the atom did Thomson then come?

• The negatively charged particles found in cathode rays normally orbit the nucleus of the atom.

• The number and arrangement of negatively charged particles in an atom are what give it its chemical properties.

• The mass of a negatively charged particle is so small that the atom must also consist of protons and neutrons.

• The atom must contain some positive charge as well as negatively charged particles because an atom is electrically neutral.

Ernest Rutherford bombarded a piece of gold foil with alpha particles. He found that most particles passed through the foil. However, a very small percentage of the particles were deflected back toward their source. Which of the following best describes Rutherford's discovery?

• Gold atoms repel alpha particles.

• A gold atom is mostly empty space.

• Gold atoms emit alpha particles.

• Gold atoms are spherical in shape.

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Which of the following is NOT a postulate in Dalton's atomic theory?

I. All matter consists of divisible particles called atoms.

II. Atoms of the same element are identical in mass and properties.

III. Atoms cannot be created or destroyed.

IV. Compounds are formed by a combination of two or more different kinds of atoms.

• I

• II

• III

• IV

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The model of an atom is consistently undergoing changes. These changes are based on new information being found. Which model had the protons and the neutrons of the atom in the middle with the electrons orbiting around them with the ability to jump energy levels?

• Rutherford Model

• Planck Model

• Bohr Model

• Quantum Model

Which model was developed after alpha particles were bombarded onto sheets of gold?

• Rutherford Model

• Planck Model

• Bohr Model

• Quantum Model

Which of the following would change the current theory of the atom?

• electrons found on an 8th energy level

• a carbon atom being discovered with 12 neutrons

• a new subatomic particle is discovered

• a new element is discovered

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