Nuclear Chemistry
Bravo – 15,000 kilotons
Nuclear Chemistry
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
178O
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.
Vocabulary
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
Element symbol
Mass number (p+ + no)
Atomic number (number of p+)
U23592
Alpha Particle Emission Beta Particle Emission
Gamma Ray Emission
Symbol
or
or
Mass
Heavy
Light
No Mass
How it changes
the nucleus
• 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
He42 α4
2 e01− β0
1−γ0
0
Types of Radioactive Decay
alpha production (α, He): helium nucleus
beta production (β, e): gamma ray production (γ):
ThHeU 23490
42
23892 +→
234 234 090 91 1Th Pa e−→ +
γ00
23490
42
23892 2++→ ThHeU
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
23892U →234
90Th + 42He Is matter conserved? Yes!
• Now you try! • Alpha radiation is emitted from Rn-222 222
86Rn → 21884Po+ 42He
Gamma particles in a reaction
• 23090Th→226
88Ra + 42He + 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 →147N + 0-1β
What Happened? • np+; 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
19K →
4020Ca + 0-1 β
What Happened? np+; 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 → 3818Ar + 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
6C + 0+1β
Stop and practice
• Packet page 16-17
