Fundamental Forces

Review of Fundamental forces

Strongest to weakest

1.Strong Nuclear Force
2.Electromagnetic Force
3.Weak Nuclear Force
4.Gravity

Forces Acting on Nucleons:

Forces of attraction between nucleons

Strong forces
– Are independent of the charge of the nucleon
– Are short range (exist only between closest

neighbors)

Electrical force (electrostatic)
– Force of repulsions between positively

charged protons

– Are long range

When are nuclei unstable? (naturally radioactive)

a.

Large nuclei (Z (atomic mass) > 82) – electrical forces of repulsion are greater than strong forces of attraction

b.

Wrong neutron : proton ratio

When are nuclei unstable?

Bigger atoms require more neutrons per

proton to keep the atom stable

A radioactive isotope:

• Has an unstable nucleus

• Spontaneously emits a particle and

decays into another element (to become
more stable)

Transmutation

• Changing into another element through

radioactive decay

Who am I?

• I worked with my husband and discovered

radium, a radioactive material

Marie and Pierre Curie

• First to discover that

compounds containing
uranium emitted
penetrating rays.

• Discovered radioactive

polonium and radium

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