CHANGES IN THE NUCLEUS
Nuclear reactions change the composition of an atom’s nucleus. All here kinds of radiate alpha, beta and gamma are produced by nuclear reactions. In fact, alpha and beta radiations consists of particles that are emitted from nucleus. Radioactivity is the spontaneous emission of radiation from an atom. Types of Radiation Identity Change Helium-4 nuclei 2+ electrons High energy nonparticle radiation 1none
Name Alpha ( £ ) Beta ( β ) Gamma( δ )
Symbol 4 2£
Penetrating Ability Low, stopped by paper Medium, stopped by heavy clothing High, stopped by lead
NOTE: When an atoms emits one of these kinds of radiation, it is said to be undergoing a radioactive decay. The best way to understand a radioactive decay is with a nuclear equation. The nuclear equation has the following form Where:
M – mass no. of the new atom Z – atomic no. of the new atom X - new symbol of the element formed
Example: Write the nuclear equation for alpha decay of gold-185. Atomic no. / Mass no. must be equal before and after the nuclear reaction mass no. of x Mass no of X 185 = M + 4 M = 81 Therefore,
Atomic no of X 79 = Z + 2 Z = 77
from the periodic table, the element with atomic number 77 is iridium The complete nuclear equation is
Exercises: 1. Write the nuclear equation for alpha decay of Uranium – 238.
2. Write the nuclear equation for the beta decay of sodium – 24.
3. What element will be formed after an alpha decay on
4. Write the nuclear equation for alpha decay of lead – 206.
5. Write the nuclear equation for beta decay of bismuth – 210.
6. Write an equation for radioactive decay of fluorine-17 by positron emission.