Question

name: ____________ date: __________ per: ____________ 4. which subatomic particle in atoms of cu - 63 and cu - 65 makes them different? explain how this particle makes the two isotopes different.

Explanation:

Isotopes are atoms of the same element with different mass - numbers. The mass - number is the sum of protons and neutrons in the nucleus. For copper isotopes Cu - 63 and Cu - 65, the number of protons is the same (as they are both copper, atomic number = 29), but the number of neutrons is different. The neutron is the subatomic particle that causes the difference. The number of neutrons in Cu - 63 is 63 - 29=34, and in Cu - 65 is 65 - 29 = 36. Neutrons contribute to the mass of the atom without affecting its chemical properties (since they are neutral). Different numbers of neutrons result in different atomic masses for the isotopes.

Answer:

The subatomic particle is the neutron. Neutrons contribute to the mass of the atom. Since the number of neutrons in Cu - 63 and Cu - 65 is different (34 and 36 respectively), while the number of protons is the same (29), the two isotopes have different atomic masses.