2.3.1 Analyzing Nuclear Reactions

Chemistry
Unit 2: Atoms and Elements
Lesson 3: Analyzing Nuclear
Reactions

Explaining Nuclear Stability

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Unit 2 Lesson 3

• To explain trends in the periodic table, you saw that the varying strengths of the attraction between the negatively charged electrons and the positively charged protons in the nucleus play an important role.

• Oppositely charged particles attract one another as a result of the electrostatic force.

• Scientists concluded, therefore, that there must be another force at work in the nucleus.

Explaining Nuclear Stability

• This force had to be opposite to the electrostatic force and sufficiently strong enough to counteract it. Scientists called this force the strong nuclear force, and found that it acted
between all particles in the nucleus.

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Explaining Nuclear Stability

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Unit 2 Lesson 3

• Nuclear forces affect both protons and neutrons. It is

convenient, therefore, to speak of these particles collectively.

• A nucleon is either a proton or a neutron.
•
• A nuclide is a nucleus with a specific number of protons and

neutrons. Unlike isotopes, nuclides can be compared without
reference to which elements are involved.

• These terms help scientists emphasize nuclear composition

rather than the chemical identity of the element.

Multiple Choice

What force holds the nucleus together?

• Strong Nuclear Force

• Electrostatic Force

• Normal Force

• Gravity

Multiple Choice

What force pushes the protons away from each other?

• Strong Nuclear Force

• Electrostatic Force

• Normal Force

• Gravity

Multiple Choice

What is the number of neutrons in Cesium?

• 55 neutrons

• 76 neutrons

• 84 neutrons

• 106 neutrons

• 139 neutrons

Multiple Choice

Nucleons are

• in the nucleus

• orbit the nucleus

• protons and electrons

• another type of neutrons

Multiple Choice

Which particle is not considered a nucleon?

• Proton

• Neutron

• Electron

Multiple Choice

The strong nuclear force is strong

• always

• only at short distances

• only at long distances

Multiple Choice

Which force can occur over a longer distance?

• strong nuclear force

• repulsive electric force

Multiple Choice

Which force is stronger in this case?

• Strong nuclear force

• Repulsive electric force

Multiple Choice

Why is the repulsive electric force (REF) stronger than the strong nuclear force (SNF) in this picture?

• Because the protons are far apart

• Because the SNF works at long distances

• Because the REF is weak at short distances

• Because the SNF overpowers the REF in this case

Multiple Choice

Why is a small nucleus more stable than a large nucleus?

• It has less electrons

• The nucleons are close together

• The repulsive force is very low

• The strong nuclear force is very low

Multiple Choice

Why is this large nucleus unstable?

• Some of the protons are touching each other

• There is not enough neutrons

• Some of the protons are too far apart

• There is not enough protons

Multiple Choice

The stability of an isotope is based on the ratio of its

• neutrons and protons

• neutrons and positrons

• electrons and positrons

• electrons and protons

Multiple Choice

Which subatomic particle seems to have a stabilizing effect on an isotope?

• protons

• neutrons

• electrons

• quarks

Multiple Choice

What is the n/p ratio of Al-30?

• 1.3

• 1.2

• 1

• 1.5

Multiple Choice

When atoms attain stability through changes within the nucleus this is known as a ___________________.

• Isotope

• Nuclear Reaction

• Band of Stability

Multiple Choice

A force that acts between protons and neutrons of atoms is called a ____________>

• Electrostatic force

• Chemical reaction

• Nuclear Force

Multiple Choice

In an atom, the strong nuclear force acts on

• protons and neutrons

• protons only

• protons, neutrons, and electrons

• neutrons only

Investigating Radioactive Decay

• Nuclei are unstable when the forces among their nucleons are unbalanced because of an excess of either protons or neutrons. 

• Unstable nuclei will spontaneously break apart. This spontaneous transformation of an unstable nucleus into a more stable form is called radioactive decay. 

• When a nucleus undergoes radioactive decay, it releases nuclear radiation in the form of energy, subatomic particles, and, in many cases, one or more new nuclei. 

• The original nuclide is called the parent nuclide, and the resulting nuclide is called the daughter nuclide. If a daughter nuclide is unstable, it will also decay.

Multiple Choice

What do scientists call isotopes with radioactive nuclei that can emit or give off smaller subatomic particles and electromagnetic radiation?

• stable isotopes

• radioactive isotopes

• electromagnetic isotopes

• strong nuclear force isotopes

Investigating Radioactive Decay

•In beta (β) decay, an unstable nuclide produces a more-stable daughter nuclide by transforming a neutron into a proton, or vice versa.

•Gamma (γ) rays are high-energy photons, a form of electromagnetic radiation, emitted from a nucleus. Gamma decay usually occurs immediately following other types of decay.

Multiple Choice

A plot of the number of neutrons versus the number of protons for stable nuclei reveals that the stable isotopes fall into a narrow band is called _____________.

• Band of Isotopes

• Band of Stability

• Band of Radioactivity

Multiple Choice

What makes something radioactive?

• elements with an atomic number above 81
• an unstable nucleus
• contaminated sewage
• It decays over time

Investigating Radioactive Decay

•Each radioactive nuclide has a specific rate at which it decays, defined by its half-life.

•One half-life is the time it takes for half of the radioactive nuclei in a sample to decay. After one half-life, half of the original nuclei will remain in the sample and half will have decayed into other nuclides.

Multiple Choice

A radioactive nuclide has a ____ stable nucleus than a non-radioactive nucleus of the same element.

• more

• less

• identical

• small