Nuclear Chemistry Nuclear Chemistry Bravo 15,000 kilotons
Radioactive elements
Radioactive elements Elements with atomic numbers greater than 83 are radioactive Why? These elements have too many protons & neutrons crammed into their nucleus to be stable. What happens? The elements decay by giving off mass & energy
Vocabulary Nuclear Reactions reactions that effect the nucleus of an atom Radioactive Decay unstable nuclei lose mass (protons/neutrons) & energy to become stable
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Vocabulary Natural transmutation - The nucleus of an atom releases a proton and changes into a different atom. Artificial (man-made) transmutation -The nucleus of an atom is hit with particles that have great quantities of energy. The particles either add to the nucleus or break apart it apart. This changes the atom into a different atom.
Discovery of Radiation Wilhelm Conrad Roentgen discovered X rays https://easyscienceforkids.com/wilhelm-conrad-roentgen-video-for-kids/ Pierre & Marie Curie Coined Radioactive Nobel Laureates Discovered several radioactive elements https://www.biography.com/video/marie-curie-mini-biography-35738691933
Types of Radiation Radiation Alpha particles Beta particles Positron Gamma particles When we are looking at any type of radiation or radioactive decay we must remember that matter is conserved!
Nuclear Symbols Mass number (p + + n o ) Element symbol 235 U 92 Atomic number (number of p + )
Alpha Particle Emission Beta Particle Emission 4 Symbol He 4 2 or α 0 2 1 e or β 0 1 Gamma Ray Emission 0 γ 0 How it changes the nucleus Mass Heavy Light No Mass Decreases the mass number by 4 Decreases the atomic number by 2 Contains 2 protons and 2 neutrons Converts a neutron into a proton Send off a fast moving e- (β) Increases atomic number by 1 -High energy radiation just energy! (gamma rays) -No change to the nucleus -emitted with alpha & beta radiation Penetration Low Medium High Protection provided by Paper, clothing Cardboard, wood Lead Danger Low, slow moving Medium, fast High
Types of Radioactive Decay alpha production (α, He): helium nucleus 238 4 U He + 92 2 234 90 Th beta production (β, e): 234 234 + 0 90 91 1 Th Pa e gamma ray production (γ): 238 4 2 234 90 U He + Th + 2 92 0 0 γ
Alpha Radiation Alpha decay is limited to VERY large, nuclei such as those in heavy metals. (α, He): helium nucleus
Alpha particles in a reaction Alpha radiation is emitted from U-238 238 92 U 234 90Th + 4 2He Is matter conserved? Yes! Now you try! Alpha radiation is emitted from Rn-222 222 218 86 Rn 84 Po+ 4 2He
Gamma particles in a reaction 230 90Th 226 88Ra + 4 2He + γ When the alpha particle is released a huge amount of energy is also released (the gamma particle)!
Beta Radiation Beta decay converts a neutron into a proton and an e- (β) is released
Beta particles in a reaction C-14 is a beta emitter, show the decay process 14 6C 14 7N + 0-1β What Happened? n p+; so atomic mass is still 14 a new p+= atomic number of 7 (now N) A β-particle flies out of the atom 0-1 β is the same as 0-1 e
Now you try 40 19 K 40 20 Ca + 0-1 β What Happened? n p+; so atomic mass is still 40 a new p+= atomic number of 20 (Ca) A β-particle flies out of the atom 0-1 β is the same as 0-1 e
Positron Particle Same mass as an electron Neutrons can be formed by protons that emit a positron They have a negligible mass Consequently they are more penetrating than alpha particles They have a charge of +1
Positrons in a reaction Potassium-38 will emit a positron, show the decay. 38 19K 38 18Ar + 0 +1β What Happened? p+ n; atomic mass is still 38 p+ n; atomic number decrease by 1; 18 (Ar) A positron flies out of the nucleus Now you try 13 7N 13 6 C + 0 +1β
Packet page 16-17 Stop and practice