P4: Atomic Structure & Radioactivity Flashcards Preview

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Flashcards in P4: Atomic Structure & Radioactivity Deck (29)
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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



Atoms of the same of the same element with a different number of neutrons in the nucleus



To expose an object to nuclear radiation



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



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.



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