Pearson Chemistry Nuclear Chemistry Chapter 25

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Questions and Answers

What does the symbol followed by ^ and a number represent?

Natural logarithm

Square root

Mass number

Exponent of the number (correct)

Approximately how many of the 1500 known nuclei are stable?

1 of 6

For elements with low atomic numbers, stable nuclei have roughly equal numbers of neutrons and protons.

True

Which isotopes have a half-life similar to that of potassium-40?

Uranium-235 and Uranium-238 Signup and view all the answers

How does the ratio of neutrons to protons for stable nuclei change as atomic number increases from 1 to 82?

Increases from 1:1 to 1:5 Signup and view all the answers

The decay reaction shows how potassium-40 decays into argon. Fill in the missing mass number and atomic number for argon.

40 (m#) 18 (a#) Ar Signup and view all the answers

A positron has the mass of a(n) , but its charge is .

Electron; Positive Signup and view all the answers

What is the conversion of an atom of one element to an atom of another element called?

Transmutation Signup and view all the answers

What are two ways transmutation can occur?

Fission and Fusion Signup and view all the answers

What is half-life?

Half-life is the time required for half the nuclei in a radioactive sample to decay. Signup and view all the answers

Uranium-238 undergoes 14 transmutations before it reaches a stable isotope of what element?

Lead-206 Signup and view all the answers

All transuranium elements are synthesized in nuclear reactors and accelerators.

True Signup and view all the answers

What is the half-life in years of carbon-14?

5.730 x 10^3 years Signup and view all the answers

How many years old is an artifact that contains 50% of its original carbon-14?

5730 Signup and view all the answers

What happens during the uncontrolled fission of 1 kg of uranium-235?

Releases energy equal to 20,000 tons of dynamite Signup and view all the answers

What part of the reactor contains the nuclear fuel?

The fuel rods Signup and view all the answers

What are the two parts of the reactor that control the fission reaction?

Moderator and control rods Signup and view all the answers

What is the role of the coolant in a nuclear reactor?

It removes heat from the reactor core. The heat is then used to generate steam. Signup and view all the answers

Where are spent fuel rods stored in a typical nuclear power plant?

They are stored in racks at the bottom of a pool. Signup and view all the answers

What happens to each pair of hydrogen nuclei during nuclear fusion?

They combine and produce 2 positrons and helium with the release of energy. Signup and view all the answers

What problem has prevented the practical use of nuclear fusion?

Temperatures required to start a fusion reaction make it difficult to contain and control. Signup and view all the answers

Why are beta particles called ionizing radiation?

They have enough energy to knock electrons off some atoms of the bombarded substance. Signup and view all the answers

What is a device that detects flashes of light after ionizing radiation strikes a specifically coated phosphor surface called?

Scintillation counter Signup and view all the answers

How is neutron activation analysis used?

By bombarding a sample with neutrons from a radioactive source. Signup and view all the answers

How is radioactive iodine-131 used as a diagnostic tool?

The thyroid gland absorbs the iodine-131 and doctors can use its image to identify diseases. Signup and view all the answers

How many half-lives must pass for all thorium-234 atoms in a sample to decay?

No, all thorium atoms will not decay in 48.2 days. Signup and view all the answers

Which reactions are not affected by external factors, such as temperature and pressure?

Nuclear reactions Signup and view all the answers

What are the three types of nuclear radiation?

Alpha, beta, and gamma Signup and view all the answers

What determines the type of decay that occurs in a radioisotope?

Its neutron to proton ratio Signup and view all the answers

What term is used for the time it takes for half of the original radioactive material to remain?

Half-life Signup and view all the answers

Transmutation can occur by bombarding the nucleus or by ________.

Radioactive decay Signup and view all the answers

In a chain reaction, what happens?

Particles released from one nuclear reaction collide with other particles and cause more nuclear reactions. Signup and view all the answers

In fusion reactions, what happens to small nuclei?

Combine, producing a larger nucleus and releasing large amounts of energy. Signup and view all the answers

In fission reactions, what happens to large nuclei?

Split into smaller nuclei. Signup and view all the answers

What three instruments are used to detect radiation?

Geiger counters, scintillation counters, and film badges. Signup and view all the answers

What are radioisotopes used to diagnose and treat?

Medical problems Signup and view all the answers

Study Notes

Nuclear Chemistry Overview

Exponents in notation indicate powers, e.g., mass number (m#) and atomic number (a#).
Of over 1500 known nuclei, approximately 1 in 6 are stable.

Properties of Stable Nuclei

For elements with low atomic numbers, stable nuclei maintain a nearly equal number of neutrons and protons.
The neutron-to-proton ratio increases from 1:1 for hydrogen to 1:5 for elements with atomic number 82.

Isotopes and Half-Life

Potassium-40 decays into argon, with key isotopes like uranium-235 and uranium-238 sharing a similar half-life.
The half-life of potassium-40 is 1.25 x 10^9 years; carbon-14 has a half-life of 5.730 x 10^3 years.

Transmutation and Radiation

Transmutation can happen via fission and fusion processes.
When potassium-40 decays, it emits beta and gamma radiation.

Nuclear Reactions

Uncontrolled fission of uranium-235 can release energy equivalent to 20,000 tons of dynamite.
A nuclear reactor's fuel is housed in fuel rods, which need periodic replacement.
The reactor uses moderators to slow down neutrons and control rods to absorb them.

Nuclear Fusion and Challenges

Hydrogen nuclei combine during nuclear fusion, producing positrons and helium while releasing energy.
Practical use of fusion is impeded by the extreme temperatures required to initiate a reaction.

Radiation Detection and Applications

Beta particles qualify as ionizing radiation due to their ability to remove electrons from atoms.
Devices like scintillation counters detect radiation through light flashes caused by ionization.
Radioactive iodine-131 is utilized in medical diagnostics for thyroid imaging.

Practical Examples and Calculations

For manganese-56, with a half-life of 2.6 hours, only 0.0625 mg remains from an original 1.0 mg after 10.4 hours (4 half-lives).
In 48.2 days, only 1/4 of a sample of thorium-234 remains after two half-lives, meaning not all atoms decay within that time.

Summary of Nuclear Radiation Types

The three types of nuclear radiation are alpha, beta, and gamma.
Nuclear reactions are unaffected by external conditions like temperature or pressure, with rates remaining constant.

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Description

This quiz covers key concepts from Chapter 25 of Pearson Chemistry, focusing on nuclear chemistry, including definitions related to exponents and atomic structure. Test your knowledge on stable nuclei and their characteristics as discussed in the chapter's sections (25.2, 25.3, 25.4).