a) 33^P
(b) 65^Cu
(c) 15^O
d) 238^U
(b) 65^Cu
(c) 15^O
d) 238^U
-
If we know the atomic number, which we can find on a periodic chart, that is how
many protons are in the nucleus of an atom of that element. We are given the mass
number, which is the sum of protons and neutrons in the nucleus. So to find the
neutron number, just subtract the atomic (or proton) number from the mass number.
In example a, phosphorus-33, P has an atomic number of 15, so the neutron
number is 33 - 15, or 18. P-33 has 15 protons and 18 neutrons.
In example b, copper-65, the atomic number is 29 so the neutron number is
65 - 29, or 36. Cu-65 has 29 protons and 36 neutrons.
In example c, O has 8 protons in the nucleus, so O-15 has 7 neutrons.
In example d, uranium has 92 protons, so U-238 has 92 protons and 146 neutrons.
many protons are in the nucleus of an atom of that element. We are given the mass
number, which is the sum of protons and neutrons in the nucleus. So to find the
neutron number, just subtract the atomic (or proton) number from the mass number.
In example a, phosphorus-33, P has an atomic number of 15, so the neutron
number is 33 - 15, or 18. P-33 has 15 protons and 18 neutrons.
In example b, copper-65, the atomic number is 29 so the neutron number is
65 - 29, or 36. Cu-65 has 29 protons and 36 neutrons.
In example c, O has 8 protons in the nucleus, so O-15 has 7 neutrons.
In example d, uranium has 92 protons, so U-238 has 92 protons and 146 neutrons.