From Isotopes to the sun…

Nuclear Chemistry

The structure of the atomA=P=EIsotopesIsotopic notation

Previous information…

Radioactivity is known as the process in which an unstable nucleus changes by emitting particles or releasing energy.

Unstable if too many protons or neutronsTwo things can be emitted from the nucleus:

Proton – Changes into a different elementNeutron – more to come…

The particle or energy given off is the source of radiation

Now… Radioactivity

Alpha (α) Beta (β)Gamma (γ)

3 main types of radiation

Alpha (α) Radiation• Alpha particles

• Positively charged.• Most massive type of radiation.• Remove protons from the nucleus.• Contains 2 protons and 2 neutrons…just

like a Helium atom.

Gives up two protons and two neutrons.

The element before the decay is like a reactant and is written on the left side of the arrow.

The new nucleus and the particle given off is the product and is written on the right side of the arrow

Alpha (α) Decay

Beta (β) Radiation• Negatively

charged.• Adds a proton

to the nucleus. HOW??

• Because a neutron splits. HOW???

• Electrons don’t belong in the nucleus….

A neutron splits into a proton and an electron.

The electron does not belong in the nucleus so it shoots out!

The mass number does not change Atomic number increases by one.

Beta (β) Decay

Do not have a charge and are not made of matter.

Cause damage because of high energy. Great danger to health High energy waves

Gamma (γ) Radiation

How strong is each one?

Quick Reminder

Half-life: The time it takes for half of a radioactive substance to decay.

After 1 half life…½ of the substance is gone…After 2 half lives…

Another ½ is gone…

But remember… Matter is neither created nor destroyed… In this instance… it decays to another form…

The Rate of Radioactive Decay

The graph below shows a typical decay curve for

The count rate halves every 15 hours. So we say its half life is 15 hours.

Starting at a count rate of 400, the time for this to half to 200 is indicated by the first horizontal pink line: 15 hours.

This can also be checked for going from 200 to 100: 15 hours.

Carbon-14 Dating

!!!

How do scientists use this?

What holds the nucleus together?The strong nuclear force

And what causes the nucleus to become unstable and begin decay?Too many protons or neutrons

Now lets look at fission vs. fusion…

So… To sum things up…

The process in which a nucleus splits into 2 or more smaller fragments releasing neutrons and releasing a lot of energy!

Nuclear Power plants use fission…So does the atomic bomb!!!

Nuclear Fission

The process in which a light nucleus combines into a heavier nucleus and releases energy.

Fusion is responsible for all elements higher than helium.

Fusion takes place in the sun

Nuclear Fusion…

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