Question

What is missing in the nuclear reaction shown below? 10 is over 5B + 4 is over 2He → ________ + 1 is over 0n 14 is over 7N 13 is over 5N 13 is over 7B 13 is over 7Na neutron

Answer 1

10 4 1

B + He ------> ? + n

5 2 0

B has 5 protons and 5 neutrons, since it's atomic mass is 10 (number of protons + neutrons) and it's atomic number is 5 (number of protons).

So:

B: 5 protons 5 neutrons

He: 2 protons 2 neutrons

?: ? protons ? neutrons

n: 0 protons 1 neutron

The number of particles have to stay the same on both sides of the equation. Matter is not being created or destroyed.

So on the left side we have 7 protons and 7 neutrons. We already have one neutron on the right side, so our unknown must have 7 protons and 6 neutrons. So:

?: 7 protons 6 neutrons

Then:

atomic mass = n° of protons + n° of neutrons = 7 + 6 = 13

atomic mass = 13

atomic number = n° of protons

atomic number = 7

Then what defines an element is its atomic number (the number of protons). The element with atomic number 7 is N

So our answer is:

13

N

7