In 2006, Soviet dissident Alexander Litvinenko was murdered when Polonium-210 was added to his tea; he died three weeks later. Polonium-210 is an alpha emitter. What other product is formed?

The first number is the atomic number(it's a subscript); the second is the mass number (it's a superscript).

84Po210 = 2He4 + 82X206
Note the subscripts add up on each side; i.e., 94 = 82 + 2 and the superscripts add up. That is 210 = 26 + 4.
So X must be Pb.

In the process of radioactive decay, Polonium-210 undergoes alpha decay, which means it emits an alpha particle. An alpha particle consists of two protons and two neutrons, which is essentially a helium nucleus (He2+). When Polonium-210 undergoes alpha decay, it loses an alpha particle from its nucleus and transforms into a different element altogether.

To determine what element is formed, we need to look at the periodic table. Polonium (Po) has an atomic number of 84, which means it has 84 protons in its nucleus. Since an alpha particle has two protons, when Polonium-210 undergoes alpha decay, its atomic number decreases by 2.

Therefore, the product formed by the alpha decay of Polonium-210 would be an element with an atomic number of 82. If we refer to the periodic table, element number 82 is lead (Pb). Hence, Polonium-210 decays into lead-206 (Po → Pb + He).

It's worth noting that radioactive decay processes can be quite complex, and there may be intermediate decay products or isotopes before the final stable product is reached. In the case of Polonium-210, there is a series of decays (known as the uranium-238 decay chain) that occur before the formation of Polonium-210, and each step in the chain results in a different element.