Final answer:
Radioactivity is the emission of particles and/or energy from an atom's nucleus, not simply the ejection of electrons. Unstable nuclei undergo radioactive decay, where they emit radiation in various forms, potentially transforming the element into another.
Step-by-step explanation:
The statement that radioactivity causes electrons to fly away from the nucleus is false. In reality, radioactivity is the spontaneous emission of particles and/or energy from the nucleus of an atom. When a nucleus is unstable, it may undergo radioactive decay, a process that changes the number of protons and/or neutrons within the nucleus, possibly resulting in the transformation of the element into another, an event known as transmutation.
The nuclei of radioactive elements emit different types of radiation, such as α particles (which are helium nuclei), β particles (which are high-speed electrons), and γ rays (which are high-energy rays similar to x-rays). The emission of these particles and energy results in a change to the structure of the nucleus, and therefore to the identity of the element itself.
It is critical to understand that the emission of electrons is just one possible outcome of radioactive decay (beta decay), and not a process that involves electrons being expelled by the nucleus itself but rather the transformation of a neutron into a proton and an electron, with the electron then being emitted.