Determine the identity of the daughter nuclide from the electron capture by 84be.

8  Li3

Explanation:

1) Electrons are called beta radiation (β)

2) Electrons are considered massless and with 1 negative charge, so in the nuclear reactions they are written as:
 0   e-1

Which means that they do not change the mass number of the isotope but reduces its atomic number in 1.

2) Then, the capture of one electron by berylium-8 means that it will reduce its atomic number in one unit and while its mass number will be the same.

3) The given isotope is:
 8
    Be  4

4) Then the resultant daughter will have the same mass number (8) and aomic number 3.

The element with atomic number 3 is Li, so it will be:

8  Li3

5) The total nuclear reaction is:

8               0         8
  Be + 1      e →     Li
4              -1         3