Bio Physics Lecture 8, HUE AHST, 2024

BIOPHYSICS FIRST LEVEL 2024-2025 Prepared By Dr. Nermin Ali Dr. Enas Lotfy Lec No. 10 Course Code: FAC-104 Page 1 Electromagnetic Radiation Page 2  Nuclei...

BIOPHYSICS FIRST LEVEL 2024-2025 Prepared By Dr. Nermin Ali Dr. Enas Lotfy Lec No. 10 Course Code: FAC-104 Page 1 Electromagnetic Radiation Page 2  Nuclei and Particles Most matter consists of an agglomeration of molecules, which can be separated relatively easily. Molecules, in turn, are composed of atoms joined by chemical bonds that are more difficult to break. Each individual atom consists of smaller particles-namely, electrons and nuclei. An atom consists largely of empty space. The nucleus is the positively charged center of an atom and contains most of its mass. It is composed of protons, which have a positive charge, and neutrons, which have no charge. Page 3 Page 4 Page 5  Radioactivity Nuclear decay or radioactivity: is the process by which a nucleus of an unstable atom loses energy by emitting ionizing radiation. ✓ Radioactivity, property exhibited by certain types of matter of emitting energy and subatomic particles spontaneously. ✓ It is, in essence, an attribute of individual atomic nuclei. Page 6 ✓ An unstable nucleus will decompose spontaneously, or decay, into a more stable configuration but will do so only in a few specific ways by emitting certain particles or certain forms of electromagnetic energy. ✓ The emissions of the most common forms of spontaneous radioactive decay are the alpha (α) particle, the beta (β) particle, and the gamma (γ) ray. Page 7 Page 8 Page 9 Types of radioactive decay Page 10 Alpha particles Page 11 Page Beta particles Page 13 Page 14  Gamma rays ✓ A third type of radiation, gamma radiation, usually accompanies alpha or beta decay. ✓ Gamma rays are photons and are without rest mass or charge. ✓ In the latter case, gamma emission may occur as the excited states transform to lower energy states of the same nucleus. Page 15 ✓ i.e. Nucleus left in an excited state after the emission of alpha or beta. ✓ Gamma rays are often emitted following Alpha or Beta decay as the daughter nucleus readjusted into the lowest energy state.) Page 16 Or Page 17 Page 18 Or Page 19  Thank You Course Code: FAC-104 Page 20