Nuclear chemistry

1. Nuclear chemistry Nuclear Radiation

2. Do now • Q1: Which particle is electrically neutral? • 1. proton 2. positron 3. neutron 4. electron • Q2: Isotopes of the same elements have the same number of • 1. protons, neutrons, and electrons • 2. protons, but different numbers of neutrons. • 3. neutrons but different numbers of protons. • 4. electrons, but different numbers of protons.

3. Nuclear radiation • - Radioactivity : • is the process by which materials give off such rays. • The penetrating rays and particles emitted by a radioactive source are called radiation. • Nuclear reactions, which account for radioactivity, differ from chemical reactions in a number of important ways.

4. Difference between chemical and nuclear reaction - In chemical reactions, atoms tend to attain stable electron configuration by losing electrons or sharing electrons. - In nuclear reactions, the nuclei of unstable isotopes, called radioisotopes, gain stability by emission of a large amount of energy. - Unlike chemical reactions, nuclear reactions are not affected by changes in temperature, pressure, or the presence of catalysts. They are also unaffected by the compounds in which the unstable isotopes are present. - The nuclear reaction of a given radioisotope can’t be speeded up, slowed down or turned off.

5. TYPES OF RADIATIONS • 1. ALPHA RADIATION: • It consists of Helium nuclei that have been emitted from a radioactive source. Each of these emitted particles, called an alpha particle, contains two protons and two neutrons and has a double positive charge. • In the nuclear equation, alpha particle is written 4 He and the charge is omitted. • Because the alpha particles cannot travel so far as its mass and charge are big so it cannot penetrate a sheet of paper.

6. Note that the nuclear equation is balanced

7. 2. Beta radiation • an electron results from the breaking apart of a neutron of an atom is called a beta particle. • The neutron breaks a part into a proton which remains in the nucleus , and a fast-moving electron, which is released.

8. A beta particle has less charge and much less mass than alpha particle and so can pass through the paper sheet but are stopped by aluminum

9. 3. Gamma radiation • - A high-energy photon emitted by a radioisotope is called a gamma ray. • - the high-energy photons are electromagnetic radiation. • - Nuclei often emit gamma rays along with alpha or beta particles during radioactive decay.

10. - because gamma rays have no charge and no mass, the emission of gamma radiation doesn’t alter the atomic number or mass number of the atom. • - gamma rays can penetrate paper, wood, and human body. But can be stopped by meters of concrete or several centimeters of lead.

11. Penetration abilities of different rays

14. Work sheet • Q1: 146 C → 714N + 01e • is an example of • 1. alpha 2. beta. Emissions. Explain • Q2 : choose and explain

15. Q3: When a stream of radioactive particles is passed through a pair of oppositely charged parallel plates, which particle would be deflected toward the negative plate? • 1. alpha particle 2. gamma photon • 3. beta particle 4. neutron • and explain .