Quick Review Flashcards - Click to flip and test your knowledge!
Question
Which particles constitute the 'nucleons' of an atom?
Answer
Protons and neutrons.
Question
What is the approximate size (order of magnitude) of an atom's nucleus?
Answer
$10^{-15}\text{ m}$ to $10^{-14}\text{ m}$.
Question
How does the size of an atom compare to the size of its nucleus?
Answer
The atom is approximately $10^5$ times larger than the nucleus.
Question
What defines the 'atomic number' ($Z$) of an element?
Answer
The total number of protons in the nucleus.
Question
The total number of nucleons in the nucleus is known as the _____.
Answer
Mass number ($A$)
Question
In a neutral atom, how does the number of electrons compare to the number of protons?
Answer
The number of electrons is equal to the number of protons.
Question
Concept: Isotopes
Answer
Definition: Atoms of the same element having the same atomic number ($Z$) but different mass numbers ($A$).
Question
Why do all isotopes of a specific element exhibit the same chemical properties?
Answer
They have the same number of electrons outside the nucleus.
Question
Concept: Isobars
Answer
Definition: Atoms of different elements which have the same mass number ($A$) but different atomic numbers ($Z$).
Question
Concept: Isotones
Answer
Definition: Atoms having a different number of protons but the same number of neutrons ($A - Z$).
Question
In the symbol $^{23}_{11}\text{Na}$, what does the number 23 represent?
Answer
The mass number ($A$).
Question
Which isotope of hydrogen has no neutrons in its nucleus?
Answer
Protium ($^1_1\text{H}$).
Question
How many neutrons are present in a tritium ($^3_1\text{H}$) nucleus?
Answer
Two.
Question
How does the energy required for a nuclear change compare to that of a chemical change?
Answer
Nuclear changes require much higher energy, approximately $10^6$ times more than chemical changes.
Question
Which scientist discovered the phenomenon of radioactivity in 1896?
Answer
Henry Becquerel.
Question
Radioactivity is defined as the _____ emission of radiations from the nuclei of atoms.
Answer
Spontaneous
Question
Why is radioactivity unaffected by physical changes like temperature or pressure?
Answer
It is a nuclear phenomenon independent of orbital electrons.
Question
What is the composition of an $\alpha$ particle?
Answer
Two protons and two neutrons (a doubly ionised helium atom).
Question
Identify the charge and mass of a $\beta$ particle.
Answer
It has a negative charge of $-1.6 \times 10^{-19}\text{ C}$ and a mass of $9.1 \times 10^{-31}\text{ kg}$.
Question
What is the nature of $\gamma$ radiation?
Answer
Highly energetic electromagnetic waves.
Question
Which of the three radioactive radiations ($\alpha$, $\beta$, $\gamma$) travels at the speed of light?
Answer
$\gamma$ radiation.
Question
How does the ionising power of $\alpha$ particles compare to $\gamma$ radiation?
Answer
The ionising power of $\alpha$ particles is approximately 10,000 times that of $\gamma$ radiation.
Question
Which radioactive radiation has the highest penetrating power?
Answer
$\gamma$ radiation.
Question
What thickness of lead is typically required to stop $\gamma$ radiations?
Answer
About $30\text{ cm}$.
Question
In a magnetic field, why are $\beta$ particles deflected more than $\alpha$ particles?
Answer
$\beta$ particles have much less mass than $\alpha$ particles.
Question
Towards which plate (positive or negative) are $\beta$ particles deflected in an electric field?
Answer
The positive plate.
Question
What change occurs to the atomic number ($Z$) during the emission of an $\alpha$ particle?
Answer
The atomic number decreases by 2.
Question
During $\beta$ emission, the mass number ($A$) of the nucleus _____.
Answer
Remains unchanged
Question
How is a $\beta$ particle created within the nucleus during radioactive decay?
Answer
By the conversion of a neutron into a proton ($n \rightarrow p + e^-$).
Question
What effect does $\gamma$ emission have on the atomic number and mass number of a nucleus?
Answer
It causes no change to either the atomic number or the mass number.
Question
Name the radioisotope commonly used in the treatment of cancer through radiotherapy.
Answer
Cobalt-60 ($^{60}\text{Co}$).
Question
What is 'carbon dating' used for in scientific research?
Answer
Estimating the age of excavated materials like rocks and dead plants.
Question
In industrial manufacturing, how are $\beta$ radiations used to control product quality?
Answer
They are used to control the thickness of materials like paper, plastic, and metal sheets.
Question
Identify two main sources of background radiation.
Answer
Cosmic rays and naturally occurring radioactive elements (like Radon-222).
Question
What is the primary safety purpose of wearing 'film badges' when working with radioactive materials?
Answer
To monitor and limit the total amount of radiation exposure over time.
Question
Einstein's mass-energy equivalence is expressed by the formula _____.
Answer
$E = \Delta m c^2$
Question
What is the energy equivalent of $1\text{ a.m.u.}$ of mass?
Answer
$931\text{ MeV}$.
Question
Concept: Nuclear Fission
Answer
Definition: The process in which a heavy nucleus splits into two lighter nuclei of nearly the same size when bombarded with slow neutrons.
Question
Approximately how much energy is released during the fission of one $^{235}_{92}\text{U}$ nucleus?
Answer
$190\text{ MeV}$.
Question
In a nuclear reactor, what is the function of 'cadmium rods'?
Answer
They act as control rods to absorb excess neutrons and control the fission rate.
Question
What is the role of a 'moderator' in a nuclear fission reaction?
Answer
To slow down fast neutrons to make them 'slow neutrons' suitable for further fission.
Question
Concept: Nuclear Fusion
Answer
Definition: The process in which two light nuclei combine to form a heavy nucleus, releasing a huge amount of energy.
Question
Why is nuclear fusion also referred to as a 'thermo-nuclear reaction'?
Answer
It requires extremely high temperatures (around $10^7\text{ K}$) to occur.
Question
What is the primary source of energy in the sun and stars?
Answer
Nuclear fusion of light nuclei (hydrogen into helium).
Question
Which process, fission or fusion, produces less hazardous radioactive waste?
Answer
Nuclear fusion.
Question
State one similarity between nuclear fission and nuclear fusion.
Answer
Both processes involve a loss in mass that is released as energy.
Question
Why must radioactive substances be stored in thick lead containers?
Answer
To absorb harmful radiations and prevent them from escaping into the environment.
Question
In terms of biological damage, how do $\alpha$ particles compare to $\gamma$ radiation when acting outside the body?
Answer
$\alpha$ particles cause less damage because they cannot penetrate the skin, unlike $\gamma$ radiation.
Question
The mass of a proton is approximately _____ times the mass of an electron.
Answer
1840
Question
Which radioactive particle is identical to a beam of electrons?
Answer
$\beta$-radiation.
Question
What is the value of the charge on an electron in Coulombs?
Answer
$-1.6 \times 10^{-19}\text{ C}$.
Question
Formula: Number of neutrons in a nucleus
Answer
$A - Z$
Question
Which radioactive radiation is unaffected by both electric and magnetic fields?
Answer
$\gamma$ radiation.
Question
When a nucleus emits a $\beta$ particle, its position in the periodic table moves _____.
Answer
One place higher
Question
Which hydrogen isotope is radioactive?
Answer
Tritium ($^3_1\text{H}$).