P4: Atomic Structure & Radioactivity Flashcards
What are electrons?
Negatively charged particles that orbit the nucleus of an atom in outer shells.
What are protons?
Positively charged particles in the middle of the nucleus of an atom.
What are neutrons?
Particles with no charge that are in the middle of the nucleus of an atom
What is a radioactive half-life?
The amount of time it takes for the nuclei to split
Alpha decay(5):
It is very easily stopped(even by a piece of paper)
Strongly effected by a magnetic field
It is the most charged and ionising particle
Heaviest particle
When an atom looses an alpha particle the atomic no.= -2
mass no. = -4
Beta radiation(4):
Much lighter than an alpha particle
Can be stopped by 5mm of aluminium
Negative charge
When an atom looses a beta particle the atomic no. =+1
Gamma radiation(4)
It is a wave Can go through aluminium but is stopped by lead It is the most penetrative No charge or mass It is hard to stop
Describe the difference between contamination and irradiation
Irradiation is to expose an object to nuclear radiation whereas contamination is the unwanted presence of materials containing radioactive atoms
What is nuclear fission?
The splitting of an atomic nucleus into parts.
What is nuclear fusion?
A reaction in which two light nuclei combine to form a
heavier nucleus with the release of energy
What plum pudding model?
The plum pudding model, by JJ Thompson, is a ball of positive charge with negative electrons spread across it.
Why did they change the plum pudding model?(2)
Geiger and Mardsen carried out this experiment where they shot alpha particles at a gold foil. This disproved the plum pudding model as some of the particles bounce of the foil , meaning the atom had a nucleus
Isotope(definition):
Atoms of the same of the same element with a different number of neutrons in the nucleus
Irradiation(definition):
To expose an object to nuclear radiation
Ionizing(definition):
Refers to radiation that can cause atoms to loose or gain electrons, becoming ions
How do smoke alarms use radiation?(3)
- Alpha particles from the alarm ionize air molecules.
- This allows positive and negative ions to constantly flow through the smoke alarm
- In case of fire the smoke alarm will be triggered by the smoke because it disturbs the flow of ions
How do X-rays use radiation?(2)
- The gamma radiation passes through the body
- A detector on the other side pics up the radiation and creates an image
How is radiation used to control the thickness of metal?
The amount of radiation which passes through a material can
be detected and used to control the thickness of the material.
Nuclear fission:
The splitting of an atomic nucleus into parts, either spontaneously or as a result of the impact of a particle usually with an associated release of energy
Nuclear fusion:
A reaction in which two nuclei combine to form a heavy nucleus with the release of energy
Radiation{definition}(2):
A type of energy that is released from the nucleus of atoms. It is the process by which atoms become stable
If the ratio between protons and neutrons is unstable…
the atom becomes unstable
Neutron radiation(definition)(2):
The release of a high speed neutron from the nucleus. can also be the result of nuclear fission.
Radioisotope(definition):
An atom with an unstable nucleus
Why is radioactivity difficult to measure?
Radioactivity is random and cannot be affected by physical changes
The radius of an atom is approximately…
1 x10^-10
Why is radiation dangerous?
Radiation can affect the way in which our cells work and cause them to mutate leading to cancers
Nuclear fission process (3):
- The unstable nucleus absorbs a neutron
- The nucleus splits into 2 smaller nuclei and emits 2 or 3 neutrons plus gamma rays
- Energy is released by the fission reaction
Background radiation(2):
- comes from natural sources such as rock and cosmic rays from space
- or it comes from man-made sources such as fallout from nuclear weapons and nuclear accidents
