nuclear strong force

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Nuclear Forces:

Nuclear Forces What keeps nuclei together?

Types of radioactivity:

Types of radioactivity Rutherford identified three types Alpha Beta Gamma Gold leaf was really a study of alpha particles Discovery of nucleus was a surprise

Types of radioactivity:

Types of radioactivity Alpha Releases large particles similar to stable helium nuclei Beta Releases small particles similar to electrons neutron  electron + proton + neutrino Uses the weak force Gamma Releases energy as photon to stabilize nucleus

Types of radioactivity:

Types of radioactivity Positron Rutherford did not detect A form of antimatter Proton essentially becomes a positron and a neutron

Results of Decay:

Results of Decay Alpha 92 238 U  2 4 He

Results of Decay:

Results of Decay Alpha 92 238 U  2 4 He + 2+?=92 4+?=238

Results of Decay:

Results of Decay Alpha 92 238 U  2 4 He + 90 234

Results of Decay:

Results of Decay Alpha 92 238 U  2 4 He + 90 234 Th Atomic number and mass number both get smaller

Results of Decay:

Results of Decay Beta 6 14 C  -1 0 e

Results of Decay:

Results of Decay Beta 6 14 C  -1 0 e + -1+?=6 0+?=14

Results of Decay:

Results of Decay Beta 6 14 C  -1 0 e + ?-1=6 0+?=14

Results of Decay:

Results of Decay Beta 6 14 C  -1 0 e + 7 14

Results of Decay:

Results of Decay Beta 6 14 C  -1 0 e + 7 14 N Atomic number got bigger, mass stayed the same

Results of Decay:

Results of Decay Positron 6 11 C  1 0 e

Results of Decay:

Results of Decay Positron 6 11 C  1 0 e + 1+?=6 0+?=11

Results of Decay:

Results of Decay Positron 6 11 C  1 0 e + 5 11

Results of Decay:

Results of Decay Positron 6 11 C  1 0 e + 5 11 B Atomic number gets smaller and mass stays the same

Forces:

Forces Gravity Attractions of bodies for each other Very, very weak Electro-Magnetic Attraction and repulsion of charges Fairly strong Weak Nuclear Controls beta and positron decay Slightly weaker than EM force

Forces:

Forces Strong Attractions of particles in nucleus Much stronger than EM Overcomes proton repulsion Hold nucleus together Works at very small distances Use velcro as a model Distance about the diameter of Fe nucleus Fe is most stable nucleus Big nuclei unstable Radioactive

Stable Nuclei:

Stable Nuclei Graph of stable nuclei Protons on the x-axis Neutrons on the y-axis

Stable Nuclei:

Stable Nuclei Band stops at 83 protons Elements with atomic number higher are not stable

Stable Nuclei:

Stable Nuclei Neutrons = Protons Near bottom Neutrons = 3 / 2 Protons Near top

Stable Nuclei:

Stable Nuclei Neutrons = Protons Near bottom Neutrons = 3 / 2 Protons Near top

Stable Nuclei:

Stable Nuclei Elements over atomic number 83 tend to alpha decay so lose both atomic number and mass number

Stable Nuclei:

Stable Nuclei Elements less than atomic number 83 but with isotopes above the line tend to beta decay so they gain atomic number and get closer to band by moving right on graph.

Stable Nuclei:

Stable Nuclei Elements less than atomic number 83 but with isotopes below the line tend to positron decay so they lose atomic number and get closer to band by moving left on graph.

Stable Nuclei:

Stable Nuclei Elements less than atomic number 83 but with isotopes below the line tend to positron decay so they lose atomic number and get closer to band by moving left on graph.

Stable Nuclei:

Stable Nuclei Predict the kind of decay for each of these isotopes…. Thorium – 234 Iodine – 125 Sulfur – 35

Stable Nuclei:

Stable Nuclei Predict the kind of decay for each of these isotopes…. Thorium – 234 Alpha Decay over 83 Iodine – 125 Sulfur – 35

Stable Nuclei:

Stable Nuclei Predict the kind of decay for each of these isotopes…. Thorium – 234 Alpha Decay over 83 Iodine – 120 Positron decay under Sulfur – 35 Beta decay over line