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Atomic Structure - Chapter 2 Nancy Dirar

All About Protons, Neutrons And Electrons

Introduction to atoms

The structure of an atom consists of three types of subatomic particles: protons, neutrons
and electrons.
Protons and neutrons form a dense nucleus.

Particle Mass Relative Charge

Proton 1 +1

Neutron 1 0


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Atomic Structure - Chapter 2 Nancy Dirar

To calculate relative atomic mass use the following formula:

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Atomic Structure - Chapter 2 Nancy Dirar



Unstable isotopes that have nuclei that break down spontaneously are described as being
radioactive and are called radioisotopes.
When the particles break down they emit rays and particles called emissions.
This break down of radioisotopes causing emission is called radioactive decay.…

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Atomic Structure - Chapter 2 Nancy Dirar

Page 5

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Atomic Structure - Chapter 2 Nancy Dirar

Beta emissions

Beta emissions involve emission of electrons, common among lighter elements with relatively large
number of neutrons.

Relative Charge -1

Relative Mass 0.00055

Nature High kinetic energy electrons produced by changing

Range in Air Few metres

Stopped By Aluminium foil as…

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Atomic Structure - Chapter 2 Nancy Dirar

Involves the emission of energy from the nucleus changing from a high energy level to a lower one
often accompanied by alpha and beta decay.

Relative Charge 0

Relative Mass 0

Nature High frequency EM radiation

Range in Air Very long distances


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Atomic Structure - Chapter 2 Nancy Dirar

Radioactive Half Life

This is the time for half to nuclei to decay.
It is a fixed time for any isotope and unaffected by amount of isotope present, chemical
form, temperature or present.
In one half-life half the radioactivity of the same disappears.…

Page 8

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Atomic Structure - Chapter 2 Nancy Dirar

The uses of radioactivity

The dangers of emissions

All radioactive emission is dangerous to living organisms due to its ionisation effects.
Can kill cells, cause genetic damage or burn effects.
Inside the body the 'danger' order is alpha > beta > gamma. The…

Page 9

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Atomic Structure - Chapter 2 Nancy Dirar

2) Must have been no movement of either parent or daughter isotope out or into a mineral since
time of crystallisation.

3) Must be no resetting of radioactive clock. Metamorphism (heating and deforming rocks) can cause
this which can cause reposition or loss…

Page 10

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Atomic Structure - Chapter 2 Nancy Dirar

3) Nuclei of hydrogen atoms in gas cloud join by fusion to create helium,
4) This releases high amounts of energy causing gas cloud to glow causing dense gas cloud to
become a star.




amazing. do you have it for anymore chem chapters.

10/5 stars all the way XD !!

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