Nuclear Chemistry

The study of reactions that take place in the nucleii of atoms Nuclear Chemistry The study of reactions that take place in the nucleii of atoms

In normal chemical reactions, only the electrons are involved

A nucleus that spontaneously decomposes Radioactive Nucleii A nucleus that spontaneously decomposes

Elements with the same atomic number, but different mass number Isotopes Elements with the same atomic number, but different mass number

Elements with = numbers of protons, but  numbers of neutrons Isotopes Elements with = numbers of protons, but  numbers of neutrons

All elements have at least one radioactive isotope Isotopes All elements have at least one radioactive isotope

Radiation The emission of particles & rays from spontaneously decomposing nucleii

Modes of Decay Alpha emission Beta emission Gamma emission Positron emission K-electron capture

Name five types of radiation Drill: Name five types of radiation

Penetration power: small Alpha Particle (a) Helium nucleus 2 protons & 2 neutrons mass = 4 amu charge = +2 Penetration power: small

Penetration power: medium Beta Particle (b) High speed electron 1 electron mass = 1/1836 amu charge = -1 Penetration power: medium

Penetration power: great Gamma Ray (g) High energy photon Electromagnetic wave mass = 0 charge = 0 Penetration power: great

Penetration power: medium Positron (p) Positive electron 1 positive electron mass = 1/1836 amu charge = +1 Penetration power: medium

The capture of an inner level e- by the nucleus K-capture The capture of an inner level e- by the nucleus 1 electron mass = 1/1836 amu charge = -1

Nuclear Symbol Alpha: 24He or 24a Beta: -10e or –10b Gamma: 0 0  Positron: +10e K-electron: -10e

Fission The splitting of a nucleus into smaller nucleii involving the release of energy

Fusion The combining of smaller nuclei into a larger one involving the release of energy

Nuclear reactions in which one element is changed into another Transmutation Rxns Nuclear reactions in which one element is changed into another

Reactions in which the nucleus of an atom is changed Transmutation Rxns Reactions in which the nucleus of an atom is changed

Both fission & fusion are examples of transmutation rxns

Can occur through emission of or bombardment by radioactive particles Transmutation Rxns Can occur through emission of or bombardment by radioactive particles

Transmutation Rxns b emission of Pm-142 a emission of U-238 K-capture by O-15 p addition of O-18

a emission of U-238 followed by two separate b emissions: Transmutation Rxns a emission of U-238 followed by two separate b emissions:

a bombardment of Th-234 followed by two separate b emission: Transmutation Rxns a bombardment of Th-234 followed by two separate b emission:

a Neutron absorption by U-238 followed by two separate b emission: Predict Products a Neutron absorption by U-238 followed by two separate b emission:

a emission of O-18 followed by a Predict Products a emission of O-18 followed by a b emission:

K-capture by V-45 followed by neutron emission then a emission Predict Products K-capture by V-45 followed by neutron emission then a emission

The rate at which a radioactive nucleus breaks down Decay Rate The rate at which a radioactive nucleus breaks down

The time it takes for 50 % of the radioactive nucleii to decompose Half-Life The time it takes for 50 % of the radioactive nucleii to decompose

Decay Rate Rate = kdX/dt ln(Xo/X) = kt1/2 k = 0.693/t1/2 t1/2 = half-life

Drill: Predict the products in each step when B-12 goes through a bombardment followed by b emission.

1st Order Age Dating Formula t = ln(Xi/Xf)t1/2 0.693

Calculate the age of a skeleton found with 0 Calculate the age of a skeleton found with 0.125 % C-14 when atmospheric C-14 = 1.00 %. t1/2 C-14 = 5720 yr

Calculate the age of a tooth found with 0 Calculate the age of a tooth found with 0.00132 % C-14 when atmospheric C-14 = 1.00 %. t1/2 C-14 = 5720

Calculate the age of a bone found with 0 Calculate the age of a bone found with 0.000300 % C-14 when atmospheric C-14 = 1.00 %. t1/2 C-14 = 5720

Mass-Energy Relations DE = Dmc2

Nuclear Fact The mass of any nuclei is different than the sum of the masses of its protons & neutrons

The energy corresponding to the mass difference can be solved using: Nuclear Fact The energy corresponding to the mass difference can be solved using: DE = Dmc2

Binding Energy The energy that holds a nucleus together which corresponds to Dm of nucleus

In an atomic bomb, 40. 00 kg of U-235 (235 In an atomic bomb, 40.00 kg of U-235 (235.401) is split into Ba-144 (14 3.223) + Kr-89 (89.335) + 2 neutrons (1.014). A) Calculate the energy released. B) Calculate the wavelength of the g ray

Show neutron bombardment of Ra-223 followed by 3 alpha emissions