Problems are listed in approximate order of difficulty. A single dot (•) indicates straigh...

Problems are listed in approximate order of difficulty. A single dot (•) indicates straightforward problems involving just one main concept and sometimes requiring no more than substitution of numbers in the appropriate formula. Two dots (••) identify problems that are slightly more challenging and usually involve more than one concept. Three dots (•••) indicate problems that are distinctly more challenging, either because they are intrinsically difficult or involve lengthy calculations. Needless to say, these distinctions are hard to draw and are only approximate.

• When the radioactive nucleus of astatine 215 decays, it tears the whole atom into two atoms, bismuth 211 and helium 4,

 215At → 211Bi + 4He

(This type of decay is called α decay because the helium 4 nucleus is often called an alpha particle.) The masses of the three atoms are

What is the kinetic energy released in the decay (in joules and in MeV)?