Fundamental Forces

Isotopes & fundamental forces

Review of Fundamental forces

Strongest to weakest

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

Multiple Choice

The forces that hold the nucleus of an atom together are

• strong nuclear forces

• weak nuclear forces

• both strong & weak nuclear forces

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

Multiple Select

What are two reasons that a nucleus might be unstable?

• Too many electrons

• Too large - mass greater than 82

• Ratio of protons and neutrons not correct

• Too few protons

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

Open Ended

How can an element change into ano

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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