When unstable elements lose particles and become more stable it is called

ions?

Explanation:

If it picks up or loses an electron, it becomes electrically charged and highly reactive. Such electrically charged atoms are known as ions. ... In an effort to achieve equilibrium, the atom emits particles in the form of radiation until the nucleus is stable. Such unstable atoms are said to be radioactive.

1 and 6 for apex

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).