Catalyst• What happens when you change the number of electrons in an atom?
• What happens when you change the number of protons in an atom?
• What happens when you change the number of neutrons in an atom?
End
Today’s Learning Targets• LT 2.11 – I can explain the forces that exist
within the nucleus of an atom. I can compare the strength of the nuclear force to other (electromagnetic, gravity, etc) forces that exist.
• LT 2.12 – I can explain why energy is released in a nuclear fusion/fission reaction and I can calculate the amount of energy released.
I. Forces• A force is a push or pull• 4 fundamental forces in
the universe1.Gravity2.Coulombic Force3.Strong Nuclear Force4.Weak Nuclear Force
I. We Have a Problem
• The nucleus of an atom contains many positive changes (protons)
• If the nucleus contains a bunch of positive charges, why doesn’t the nucleus of the atom split apart?
II. Strong Nuclear Force
• The strong nuclear force is the force that exists between particles in the nucleus of an atom
• Much stronger then coulombic forces, so the attraction between particles in nucleus is much stronger then the proton repulsion
III. Weak Nuclear Forces
• The weak nuclear force is the force that allows certain elements to become radioactive.
Strength of the ForcesStrong Nuclear Force
Electromagnetic Force
Weak Nuclear Force
Gravitational ForceWeakest Force
Strongest Force
SUMMARIZEUse the following terms in your summary:• Force• Gravitational• Electromagnetic• Strong• Weak
I. Nuclear Fusion
• Fusion – When two things combine into one• Nuclear fusion is when two atomic nuclei fuse
into one new, HEAVIER, atom
II. Nuclear Fission• Fission – Splitting of an item into two• Nuclear fission is when a very heavy nucleus
splits into two smaller, more stable nucleuses
Today’s Learning Targets• LT 2.13 – I can compare and contrast normal isotopes
and radioactive isotopes. I can discuss the three forms of decay that radioactive isotopes can undergo and how the nucleus is altered in each type of decay.
• LT 2.14 – I can list the three different type of radiation and the impact that each one of these types of decay can have on myself and other living matter
I. Isotopes• Isotope – Atoms of the same element have
different numbers of neutrons and thus have different atomic masses.
I. Radioactive Decay• Atoms can be unstable and breakdown• Radioactive Decay – The spontaneous breakdown
of the nucleus into a smaller nucleus, accompanied by the release of particles, radiation, or both.
I. Alpha (α) Decay• Alpha Decay – When an atom splits its nucleus into:
1. A smaller nucleus and 2. A Helium atom (2 protons, 2 neutrons).
• Observed often in very heavy atoms• Alpha particles on travel a few cm in air• Paper blocks alpha particles
II. Beta (β) Decay• Some elements are unstable because their proton to
neutron ratio is too large.• Beta decay converts neutrons to protons and releases
an electron known as a beta particleneutron proton + β
• Travel a few meters in the air• Metals provide a shield against beta radiation.
Electron
III. Gamma (γ) Decay• Gamma rays are high energy waves that are
released when nucleus goes from high energy state to low energy.
• Gamma radiation is the most dangerous. It can lead to DNA mutations and cancers.
• Gamma radiation requires thick pieces of lead/concrete in order to stop.
Radiation SummaryType of Radiation Description Blocked by?
Alpha (α)
Beta (β)
Gamma (γ)
The spitting of a nucleus into a smaller nucleus and a He atom (alpha particle
Converts a neutron to a proton and an electron
(beta particle)
High energy waves that are released by nucleus
Blocked by paper
Blocked by metals
Blocked by lead
Online Simulator• Please open the two simulators on the computer
and complete the simulator handout with a partner.
Learning Target Log Assessment
• Rate your current level of understanding of LT 9.3 and 9.4. Rate yourself 1 – 4.
Exit Slip
1. What is fusion?2. What is gamma decay? What will stop gamma
radiation?3. What type of decay is shown below:
23191Pa 227
89Ac + 42He
Exit Ticket
1. What is a force?2. How does the strong nuclear force allow for
the nucleus of an atom to remain together?3. Rank the 4 fundamental forces from weakest
to strongest.
Learning Target Log Assessment
• Rate your current level of understanding of LT 9.3 and 9.4. Rate yourself 1 – 4.