A nucleus with mass number A and atomic number Z is represented as (A, Z).
Alpha particles carry a positive charge, beta particles carry a negative charge, and gamma rays are neutral.
She and her husband, Pierre, soon discovered two new radioactive elements, which she named polonium, after her native land of Poland, and radium, because it radiates.
These two new elements filled holes in the periodic table and displayed much higher levels of radioactivity than uranium.
A substance or object that emits nuclear radiation is said to be radioactive.
Becquerel found radiation to be associated with certain elements, such as uranium.
Some isotopes of a given element are more unstable than others, causing a nuclear reaction which releases energy to achieve a more stable nuclear configuration.