Nuclear Chemistry HW Quiz

Which of the following is the best description of gamma rays?

• neutrons

• high energy electromagnetic waves

• helium nuclei

• electrons

Answer explanation

Gamma rays are best described as high energy electromagnetic waves. They are a form of radiation with very short wavelengths and high frequency, distinguishing them from neutrons, helium nuclei, and electrons.

Which of the following is the same as a beta particle?

• an electron

• a high energy electromagnetic wave

• a neutron

• a helium nucleus

Answer explanation

A beta particle is essentially an electron, which is emitted during beta decay. The other options, such as a neutron and a helium nucleus, do not represent beta particles, and high energy electromagnetic waves are gamma rays.

Which of the following is the same as an alpha particle?

• a high energy electromagnetic wave

• an electron

• a helium nucleus

• a neutron

Answer explanation

An alpha particle is composed of 2 protons and 2 neutrons, which is identical to a helium nucleus. Therefore, the correct answer is 'a helium nucleus', while the other options do not represent an alpha particle.

What is the term for any subatomic particle found in the nucleus of an atom?

• alpha particle

• nuclide

• nucleus

• nucleon

Answer explanation

The term 'nucleon' refers to any subatomic particle found in the nucleus of an atom, which includes protons and neutrons. Other options like 'alpha particle' and 'nuclide' do not specifically denote particles in the nucleus.

Complete the following transmutation equation:

⁹₄Be → ⁹₅B + ____

• ¹₀n

• ⁰_-1e

• ¹₁H

• ⁴₂He

Answer explanation

In the transmutation of beryllium-9 to boron-9, a beta particle (electron) is emitted. This is represented as ⁰_-1e, indicating a negative charge and no mass, making it the correct answer.

Why are protons able to exist side by side in the nucleus of an atom?

• At close distances the repulsive electric force disappears.

• The strong nuclear force is stronger than the repulsive electric force.

• Electrons in the nucleus prevent the repulsive electric force from getting too large.

• The strong nuclear force pulls electrons close to the nucleus to balance the repulsive electric force.

Answer explanation

Protons can exist side by side in the nucleus because the strong nuclear force, which binds them together, is significantly stronger than the repulsive electric force that arises from their positive charges.

Classify the following reactions:

¹⁶⁷₇₇Ir  → ⁴₂He + ¹⁶³₇₅Al​ (a)  

⁹⁹₄₃Tc  → ⁹⁹₄₃Tc + ⁰₀γ​ (b)  

³⁸₁₇Cl  → ⁰_-1e + ³⁸₁₈Ar​ (c)  

• Alpha particle emission

• Gamma ray emission

• Beta particle emission

Answer explanation

The first reaction shows alpha particle emission (He), the second is gamma ray emission (γ), and the third is beta particle emission (e). Each reaction type is identified by the particles emitted.

What does the 2 in ⁴₂He represent?

• the number of neutrons

• the mass number

• the atomic number

• the number of nucleons

Answer explanation

The 2 in \( ^4_2He \) represents the atomic number, which indicates the number of protons in the nucleus of the helium atom. This distinguishes helium from other elements on the periodic table.

What does the 218 in Polonium-218 represent?

• the mass defect

• the mass number

• the atomic number

• the neutron number

Answer explanation

The 218 in Polonium-218 represents the mass number, which is the total number of protons and neutrons in the nucleus of the atom. It is not the atomic number, mass defect, or neutron number.

Which of the following is the best definition of half-life?

• The mass remaining after an isotope undergoes nuclear fusion

• The mass remaining after an isotope undergoes nuclear fission

• The time required for half of a radioactive isotope to undergo radioactive decay

• The time required for half of a radioactive isotope to react chemically

Answer explanation

The best definition of half-life is the time required for half of a radioactive isotope to undergo radioactive decay, which describes the process of decay rather than fusion or fission.