Isotopes
Bismuth has 33 different isotopes, but bismuth-209 is the only naturally occurring isotope. Each isotope has a mass number that ranges between 185 and 217. However, only 209Bi is considered to be effectively stable, though in reality it is radioactive with a very slow decay rate. 209Bi is the most common radioactive isotope of bismuth. Bismuth is considered to be non-toxic and is not harmful to humans. In fact, one of it's many uses is in medications.
Characteristics of Pnictogen Metals
The name "pnictogen" is not recognized by the IUPAC (International Union of Pure and Applied Chemistry) but many chemists now use this term to describe them. Each member of this group has 5 valence electrons, which allows these elements to from double and triple bonds. Pnictogen elements can lose, gain or share any of their valence electrons.
Characteristics of post-transition metals
Post-transition metals are metallic metals included in the p-block of the periodic table. Post-transition metals include aluminum, indium, gallium, tin, bismuth, lead and thallium. Post-transition metals are more electronegative than transition metals. A post-transition metal's melting and boiling points are generally lower than those of transition metals, and they are softer metals.