Chapter 13 - Nuclear Reactions

What are isotopes?

Different forms of the same element that possess same number of protons but different number of neutrons

What does binding energy do?

It is the energy that holds the neutrons and protons in place at the centre of the atom

As binding energy increases, what happens to the stability of the overall nucleus?

Nucleus becomes more stable as the protons and neutrons are held more firmly in place

What does the mass defect refer to?

As the nucleus is created, a portion of the mass of the nucleons is converted into binding energy which is needed to hold the components together

Which famous equation depicts the relationship between binding energy and mass defect?

Einstein's E = Δmc2, where E is the binding energy, Δm is the mass defect, and c is the speed of light

What occurs during nuclear fission?

A very heavy nucleus splits into two or more lighter nuclei of almost equal mass, releasing neutrons in the process.

What occurs during nuclear fusion?

Two or more lighter nuclei fuse into one larger nucleus, releasing energy

Why does radioactive decay occur?

Radioactive decays allows the nucleus of an unstable element to spontaneously convert into a more stable element while emitting a radioactive particle

What are the three routes of radioactive decay?

Alpha, beta, and gamma

Which radioactive particle has the lowest penetrating power?

Alpha

Which radioactive particle has the highest penetrating power?

Gamma

Elements with an atomic number of ≤ 20 will decay to attain a N/Z ratio of what?

N/Z ratio of 1

Which is the only type of decay that results in change of mass number?

Alpha particle decay

What particle is emitted during alpha decay?

An alpha particle, which consists of 2 neutrons and 2 protons.

What is the alpha particle equivalent to?

A helium atom, as it consists of 2 neutrons and 2 protons

If uranium (atomic number 92) undergoes alpha decay, what would the products be?

Thorium (atomic number 90) and an alpha particle

How many types of beta particles are there?

Two. β- (aka electron) and β+ (aka positron).

What is consumed and emitted during β- decay?

Neutron converted into a proton, and an electron is emitted

What is consumed and emitted during β+ decay?

A proton converts into a neutron, and a positron is emitted

Is β- decay more likely to occur when N/Z ratio of an element with atomic number ≤ 20 is greater or less than 1?

Greater than 1

Is β+ decay more likely to occur when N/Z ratio of an element ≤ 20 is greater or less than 1?

Less than 1

What occurs during electron capture?

Electron capture is a special case of beta decay. The positive nucleus 'captures' an electron from its innermost shell, combining it with a proton to form a neutron

Do gamma particles have high frequency or low frequency?

High frequency. This is why they are considered the most penetrating radioactive decay particle

Is radioactive decay zero, first, or second-order reactions?

First-order

There is a sample of 120 grams of Pb 208. Pb has a half life of 6 hrs. How much lead is left after 24 hrs?

7.5g

There is a sample of 120 grams of lead-208. Lead has a half life of 6 hrs. How much lead is left after 36 hrs?

1.875g

There is sample of 20 grams of sulfur-32. Sulfur has a half life of 15 days. How much sulfur has decayed after 45 days?

17.5g