Which two particles are found in the nucleus of an atom?

The nucleus of an atom contains protons and neutrons .

Where are electrons found in an atom?

Electrons are found orbiting the nucleus .

True or False? Electrons make up most of the mass of an atom.

False. Most of the mass of an atom is concentrated in the nucleus . Electrons have a negligible mass compared to protons and neutrons.

What is the charge on the nucleus of an atom?

The charge on the nucleus is positive .

True or False? An atom is neutral because it has an equal number of protons and neutrons.

False. An atom is neutral because it has an equal number of protons and electrons .

What is meant by the term atomic number ?

The atomic number of an atom is the number of protons in its nucleus. This number defines the chemical element.

What is meant by the term mass number ?

The mass number of an atom is the total number of protons and neutrons in its nucleus.

Define the term isotope .

Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons .

True or False? An element can have only one isotope.

False. An element can have more than one isotope.

True or False? Two different isotopes of uranium have the same number of neutrons.

False. Two different isotopes of uranium have the same number of protons but a different number of neutrons .

Why do some nuclei emit radiation?

Some nuclei emit radiation because they are unstable due to having an imbalance of protons or neutrons.

True or False? The emission of radiation from a nucleus is a spontaneous and random process.

True. The emission of radiation from a nucleus is a spontaneous and random process.

What is an alpha particle ?

An alpha particle is composed of two protons and two neutrons . It is equivalent to a helium nucleus.

What is a beta particle ?

A beta particle is a fast-moving electron .

What is gamma radiation ?

Gamma radiation is a type of high-energy electromagnetic wave .

True or False? Alpha particles have a charge of -1.

False. Alpha particles have a charge of +2 due to having two positively charged protons . It is beta particles that have a charge of -1 due to the negatively charged electron .

Which type of nuclear radiation is the most ionising ?

Alpha particles are the most ionising form of nuclear radiation. Beta particles are next, and gamma radiation is the least ionising.

List the three types of nuclear radiation in order of increasing penetrating power .

The types of nuclear radiation in order of increasing penetrating power are: alpha ( least penetrating, can be stopped by paper ) beta (can stopped by a few mm of aluminium ) gamma ( most penetrating, can be reduced by a few mm of lead )

Which types of nuclear decay cause the isotope to decay into a new element?

An isotope will decay into a new element if the number of protons changes. Therefore, alpha and beta decay will produce a new element.

By what value does the mass number decrease as a result of alpha decay?

Alpha decay results in the mass number decreasing by 4 , because 4 nucleons are emitted.

True or False? In beta decay, a neutron changes into a proton and an electron.

True. A neutron changes into a proton and an electron during beta decay. The high-energy electron is emitted from the nucleus.

By what value does the atomic number decrease as a result of alpha decay?

Alpha decay results in the atomic number decreasing by 2 , because 2 protons are emitted.

How are the mass and atomic numbers affected by gamma decay?

Gamma decay has no effect on the mass number or the atomic number . Gamma radiation reduces the energy of the nucleus but has no effect on the number of particles.

By what value does the atomic number change as a result of beta decay?

The atomic number increases by 1 as a result of beta decay. A neutron changes into a proton and an electron. The extra proton causes the atomic number to increase by 1, so a new element is formed.

By what value does the charge on a nucleus decrease when it emits an alpha particle?

The charge on a nucleus will decrease by 2 after it emits an alpha particle because 2 protons are emitted.

By what value does the mass number decrease as a result of beta decay?

The mass number remains unchanged by beta decay. A neutron changes into a proton which has the same mass. A beta particle is emitted but this change in mass is negligible.

Name two methods of detecting ionising radiation.

Ionising radiation can be detected using: photographic film a Geiger-Muller tube / counter

Define background radiation .

Background radiation is the radiation that exists around us all the time.

True or False? Radiation is solely a human-made phenomenon.

False. Radiation is a natural phenomenon that has always existed on Earth and in outer space.

What are the natural sources of background radiation?

Natural sources of background radiation include: radon gas cosmic rays from space radioactive elements in rocks and soil carbon-14 in biological material some food and drink

True or False? Ionising radiation can be measured using a detector connected to an emitter.

False. Ionising radiation can be measured using a detector connected to a counter .

What are the units of count rate?

Count rate is measured in counts per second or counts per minute.

True or False? A corrected count rate can be calculated by adding the count rate found with no radioactive source present to the count rate with the radioactive source present.

False. A corrected count rate can be calculated by subtracting the count rate found with no radioactive source present from the count rate with the radioactive source present.

Does the count rate increase or decrease as the detector moves further away from a source of radiation?

The count rate decreases as the detector moves further from the radiation source.

IGCSEPhysicsEdexcelFlashcards7. Radioactivity & ParticlesProperties of Radiation

Properties of Radiation (Edexcel IGCSE Physics)

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Which two particles are found in the nucleus of an atom?
The nucleus of an atom contains protons and neutrons.
Where are electrons found in an atom?
Electrons are found orbiting the nucleus.
True or False?
Electrons make up most of the mass of an atom.
False.
Most of the mass of an atom is concentrated in the nucleus. Electrons have a negligible mass compared to protons and neutrons.
What is the charge on the nucleus of an atom?
The charge on the nucleus is positive.
True or False?
An atom is neutral because it has an equal number of protons and neutrons.
False.
An atom is neutral because it has an equal number of protons and electrons.
What is meant by the term atomic number?
The atomic number of an atom is the number of protons in its nucleus. This number defines the chemical element.
What is meant by the term mass number?
The mass number of an atom is the total number of protons and neutrons in its nucleus.
How can the notation below be used to determine the number of protons, neutrons and electrons in atom X?
In nuclear notation:
- X represents the chemical symbol
- A represents the mass number (number of protons and neutrons)
- Z represents the atomic number (number of protons)
Therefore, Z = number of protons = number of electrons, and A - Z = number of neutrons.
What is the mass number and atomic number of carbon?
The mass number (top number) of carbon is 12.
The atomic number (bottom number) of carbon is 6.
How many protons, neutrons and electrons are in an atom of beryllium?
The mass number (top number) of beryllium is 9.
The atomic number (bottom number) of beryllium is 4.
Therefore, an atom of beryllium contains 4 protons, 5 neutrons and 4 electrons.
Define the term isotope.
Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons.
True or False?
An element can have only one isotope.
False.
An element can have more than one isotope.
True or False?
Two different isotopes of uranium have the same number of neutrons.
False.
Two different isotopes of uranium have the same number of protons but a different number of neutrons.
True or False?
The following atoms are all possible isotopes of chlorine (symbol Cl):
${}_{17}^{35}{Cl}$ , ${}_{18}^{35}{Cl}$ , ${}_{19}^{35}{Cl}$ , ${}_{20}^{35}{Cl}$
False.
The atoms ${}_{17}^{35}{Cl}$ , ${}_{18}^{35}{Cl}$ , ${}_{19}^{35}{Cl}$ , ${}_{20}^{35}{Cl}$ are not possible isotopes of chlorine as they have the same mass number but different atomic numbers.
Isotopes of an element must have the same atomic number but different mass numbers.
True or False?
The following atoms are all possible isotopes of iron (symbol Fe):
${}_{26}^{54}{Fe}$ , ${}_{26}^{56}{Fe}$ , ${}_{26}^{57}{Fe}$ , ${}_{26}^{58}{Fe}$
True.
The atoms ${}_{26}^{54}{Fe}$ , ${}_{26}^{56}{Fe}$ , ${}_{26}^{57}{Fe}$ , ${}_{26}^{58}{Fe}$ are all possible isotopes of iron as they have the same atomic number but different mass numbers.
Why do some nuclei emit radiation?
Some nuclei emit radiation because they are unstable due to having an imbalance of protons or neutrons.
What are the three types of radiation that a nucleus can emit?
The three types of radiation that a nucleus can emit are:
- alpha ( $α$ )
- beta ( $β$ )
- gamma ( $γ$ )
True or False?
The emission of radiation from a nucleus is a spontaneous and random process.
True.
The emission of radiation from a nucleus is a spontaneous and random process.
What is an alpha particle?
An alpha particle is composed of two protons and two neutrons. It is equivalent to a helium nucleus.
What is a beta particle?
A beta particle is a fast-moving electron.
What is gamma radiation?
Gamma radiation is a type of high-energy electromagnetic wave.
True or False?
Alpha particles have a charge of -1.
False.
Alpha particles have a charge of +2 due to having two positively charged protons. It is beta particles that have a charge of -1 due to the negatively charged electron.
Which type of nuclear radiation is the most ionising?
Alpha particles are the most ionising form of nuclear radiation. Beta particles are next, and gamma radiation is the least ionising.
List the three types of nuclear radiation in order of increasing penetrating power.
The types of nuclear radiation in order of increasing penetrating power are:
- alpha (least penetrating, can be stopped by paper)
- beta (can stopped by a few mm of aluminium)
- gamma (most penetrating, can be reduced by a few mm of lead)
Which types of nuclear decay cause the isotope to decay into a new element?
An isotope will decay into a new element if the number of protons changes. Therefore, alpha and beta decay will produce a new element.
By what value does the mass number decrease as a result of alpha decay?
Alpha decay results in the mass number decreasing by 4, because 4 nucleons are emitted.
True or False?
In beta decay, a neutron changes into a proton and an electron.
True.
A neutron changes into a proton and an electron during beta decay. The high-energy electron is emitted from the nucleus.
By what value does the atomic number decrease as a result of alpha decay?
Alpha decay results in the atomic number decreasing by 2, because 2 protons are emitted.
How are the mass and atomic numbers affected by gamma decay?
Gamma decay has no effect on the mass number or the atomic number. Gamma radiation reduces the energy of the nucleus but has no effect on the number of particles.
By what value does the atomic number change as a result of beta decay?
The atomic number increases by 1 as a result of beta decay. A neutron changes into a proton and an electron. The extra proton causes the atomic number to increase by 1, so a new element is formed.
By what value does the charge on a nucleus decrease when it emits an alpha particle?
The charge on a nucleus will decrease by 2 after it emits an alpha particle because 2 protons are emitted.
By what value does the mass number decrease as a result of beta decay?
The mass number remains unchanged by beta decay. A neutron changes into a proton which has the same mass. A beta particle is emitted but this change in mass is negligible.
Name two methods of detecting ionising radiation.
Ionising radiation can be detected using:
- photographic film
- a Geiger-Muller tube / counter
Define background radiation.
Background radiation is the radiation that exists around us all the time.
True or False?
Radiation is solely a human-made phenomenon.
False.
Radiation is a natural phenomenon that has always existed on Earth and in outer space.
What are the natural sources of background radiation?
Natural sources of background radiation include:
- radon gas
- cosmic rays from space
- radioactive elements in rocks and soil
- carbon-14 in biological material
- some food and drink
True or False?
Ionising radiation can be measured using a detector connected to an emitter.
False.
Ionising radiation can be measured using a detector connected to a counter.
What are the units of count rate?
Count rate is measured in counts per second or counts per minute.
True or False?
A corrected count rate can be calculated by adding the count rate found with no radioactive source present to the count rate with the radioactive source present.
False.
A corrected count rate can be calculated by subtracting the count rate found with no radioactive source present from the count rate with the radioactive source present.
Does the count rate increase or decrease as the detector moves further away from a source of radiation?
The count rate decreases as the detector moves further from the radiation source.

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