Copper (atomic number = 29) has two isotopes: Cu-63 (atomic mass = 63) and Cu-65 (atomic mass = 65). How many of each subatomic particle are in Cu-65?
The Correct Answer and Explanation is:
Correct Answer:
For Cu-65 (Copper-65):
- Protons: 29
- Neutrons: 36
- Electrons (in a neutral atom): 29
Explanation:
Cu-65, or Copper-65, is one of the naturally occurring isotopes of the element copper. The notation “Cu-65” indicates an isotope of copper with a mass number of 65. The mass number of an atom is the total number of protons and neutrons in its nucleus.
Copper’s atomic number is 29, which means every atom of copper has 29 protons in its nucleus. The atomic number is what defines the element—any atom with 29 protons is a copper atom, regardless of how many neutrons it has.
To find the number of neutrons in Cu-65, subtract the atomic number from the mass number:Neutrons=Mass number−Atomic number=65−29=36\text{Neutrons} = \text{Mass number} – \text{Atomic number} = 65 – 29 = 36Neutrons=Mass number−Atomic number=65−29=36
So, Cu-65 has 36 neutrons.
In a neutral atom, the number of electrons is equal to the number of protons because the positive charges from the protons are balanced by the negative charges from the electrons. Since Cu-65 is neutral (unless otherwise stated), it has:Electrons=Protons=29\text{Electrons} = \text{Protons} = 29Electrons=Protons=29
Therefore, in a single atom of Cu-65:
- The nucleus contains 29 protons and 36 neutrons, giving it a total mass of 65 atomic mass units (u).
- There are 29 electrons orbiting the nucleus in various energy levels or shells.
This isotopic structure allows Cu-65 to behave chemically like all other copper atoms, because chemical behavior is governed by electrons and especially the electrons in the outermost shell, which are the same for all copper isotopes.
