Silver has an atomic number of 47.
a. Give the number of protons, neutrons, and electrons in a neutral atom of the most common isotope, Ag-107.
b. How do the numbers of protons, neutrons, and electrons in a neutral atom of Ag-109 compare with those of Ag-107?
The correct answer and explanation is :
a. Number of protons, neutrons, and electrons in a neutral atom of Ag-107:
Silver (Ag) has an atomic number of 47, meaning it has 47 protons in its nucleus. The most common isotope of silver is Ag-107.
- Protons: The number of protons in any neutral atom of silver is 47 (because the atomic number is 47).
- Electrons: In a neutral atom, the number of electrons equals the number of protons. Therefore, Ag-107 also has 47 electrons.
- Neutrons: The number of neutrons can be determined by subtracting the atomic number from the mass number. The mass number of Ag-107 is 107, so the number of neutrons is:
[
\text{Neutrons} = \text{Mass number} – \text{Atomic number} = 107 – 47 = 60
]
Thus, in a neutral atom of Ag-107:
- Protons: 47
- Electrons: 47
- Neutrons: 60
b. Comparison of Ag-109 with Ag-107:
Ag-109 is another isotope of silver, with a mass number of 109. While the atomic number of silver remains 47 (meaning the number of protons is always 47), the difference between Ag-107 and Ag-109 lies in the number of neutrons.
- Protons: Both Ag-107 and Ag-109 have the same number of protons because they are isotopes of silver. Therefore, both isotopes have 47 protons.
- Electrons: Since both Ag-107 and Ag-109 are neutral atoms, they must also have the same number of electrons. Therefore, both isotopes have 47 electrons.
- Neutrons: The number of neutrons differs between Ag-107 and Ag-109 due to their different mass numbers:
- For Ag-107, the number of neutrons is ( 107 – 47 = 60 ).
- For Ag-109, the number of neutrons is ( 109 – 47 = 62 ).
Thus, the main difference between Ag-107 and Ag-109 is in the number of neutrons. Ag-109 has 2 more neutrons than Ag-107, which accounts for the difference in their mass numbers (109 vs. 107). These neutrons contribute to the mass of the atom but do not affect its chemical properties, as the number of protons (and electrons) remains constant.
Summary:
- Both Ag-107 and Ag-109 have 47 protons and 47 electrons.
- Ag-107 has 60 neutrons, while Ag-109 has 62 neutrons.
- The difference in the number of neutrons between these isotopes is what gives them different mass numbers.