1st Semester final review #1: At. Theory and Radioactivity

What is the hottest part of the bunsen burner flame?

• tip of the inner blue cone

• tip of the outer blue cone

• the base of the flame

• the whole flame is equally hot

Which statement describes how an atom in the ground state becomes excited?

• The atom releases energy, and one or more electrons move to a higher electron shell.

• The atom releases energy, and one or more electrons move to a lower electron shell.

• The atom absorbs energy, and one or more electrons move to a higher electron shell.

• The atom absorbs energy, and one or more electrons move to a lower electron shell.

The modern model of the atom shows that electrons are —

• combined with neutrons in the nucleus.

• found in regions called orbitals.

• located in a solid sphere covering the nucleus.

• orbiting the nucleus in fixed paths

Compared to the atomic radius of a sodium atom, the atomic radius of a magnesium atom is smaller. The smaller radius is primarily a result of the magnesium atom having —

• fewer principal energy levels.

• more principal energy levels.

• a smaller nuclear charge.

• a larger nuclear charge.

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NGSS.HS-PS1-1

Which sequence represents the correct order of historical developments leading to the modern model of the atom?

• The atom is a hard sphere. Electrons exist in orbitals outside the nucleus. Most of the atom is empty space.

• Most of the atom is empty space. The atom is a hard sphere. Electrons exist in orbitals outside the nucleus.

• Most of the atom is empty space. Electrons exist in orbitals outside the nucleus. The atom is a hard sphere.

• The atom is a hard sphere. Most of the atom is empty space. Electrons exist in orbitals outside the nucleus.

Experiments conducted by Rutherford with gold foil indicated that atoms —

• usually have a uniform distribution of negative charges.

• contain a positively charged, dense center.

• usually have a uniform distribution of positive charges.

• contain a negatively charged, dense center.

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

• proton

• neutron

• positron

• electron

Which statement is not true of fission reactions?

• Stable, lightweight nuclei start the process

• Several neutrons are emitted that can start a chain reaction

• A neutron runs into a large nucleus to start the process

• a very heavy nucleus splits into several medium-weight nuclei

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NGSS.HS-PS1-8

Right now on Earth, fusion reactions

• produce the energy in most nuclear power plants

• cannot be used to produce energy in reactors

• produce the energy in all recent nuclear power plants

• produce the energy in some nuclear power plants

Which of the following is the nuclear symbol for a beta particle?

• 
• 
• 
• 

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NGSS.HS-PS1-8