Give the number of protons, the number of neutrons, and the neutron-to-proton ratio for each of the isotope below. a. iron-57 b. 185W c. potassium-39 d. 131Xe 2. Write the nuclide notation for atoms with the following characteristics: a. 25 protons, 20 neutrons, 24 electrons b. 45 protons, 24 neutrons, 43 electrons c. 53 protons, 89 neutrons, 54 electrons d. 97 protons,
T he Correct Answer and Explanation is :
Sure! Here’s a complete and clear answer for both parts of your question, followed by a 300-word explanation.
1. For each isotope, give the number of protons, neutrons, and neutron-to-proton ratio:
a. Iron-57 (⁵⁷Fe):
- Protons: 26 (Iron’s atomic number)
- Neutrons: 57 – 26 = 31
- Neutron-to-proton ratio: 31 / 26 ≈ 1.19
b. Tungsten-185 (¹⁸⁵W):
- Protons: 74 (Tungsten’s atomic number)
- Neutrons: 185 – 74 = 111
- Neutron-to-proton ratio: 111 / 74 ≈ 1.50
c. Potassium-39 (³⁹K):
- Protons: 19 (Potassium’s atomic number)
- Neutrons: 39 – 19 = 20
- Neutron-to-proton ratio: 20 / 19 ≈ 1.05
d. Xenon-131 (¹³¹Xe):
- Protons: 54 (Xenon’s atomic number)
- Neutrons: 131 – 54 = 77
- Neutron-to-proton ratio: 77 / 54 ≈ 1.43
2. Write the nuclide notation:
Nuclide notation: ZASymbolcharge_{Z}^{A}\text{Symbol}^{\text{charge}}
a. 25 protons, 20 neutrons, 24 electrons
- Element: Manganese (Mn)
- Mass number (A): 25 + 20 = 45
- Charge: 25 – 24 = +1
- Notation: 2545Mn+1_{25}^{45}\text{Mn}^{+1}
b. 45 protons, 24 neutrons, 43 electrons
- Element: Rhodium (Rh)
- Mass number: 45 + 24 = 69
- Charge: 45 – 43 = +2
- Notation: 4569Rh+2_{45}^{69}\text{Rh}^{+2}
c. 53 protons, 89 neutrons, 54 electrons
- Element: Iodine (I)
- Mass number: 53 + 89 = 142
- Charge: 53 – 54 = –1
- Notation: 53142I−1_{53}^{142}\text{I}^{-1}
d. 97 protons (mass not given)
- Element: Berkelium (Bk)
- Common isotope mass number: Assume Bk-247
- Notation (neutral atom): 97247Bk_{97}^{247}\text{Bk}
Explanation
Atoms consist of three subatomic particles: protons, neutrons, and electrons. The number of protons determines the atomic number and the identity of the element. Neutrons contribute to the atomic mass but not the charge. Electrons are negatively charged and balance the protons in neutral atoms.
In isotopes, the number of neutrons varies while the number of protons remains the same. This leads to different mass numbers (A = protons + neutrons). The neutron-to-proton ratio is important in determining the stability of a nucleus. Lighter elements (like potassium) tend to have ratios close to 1, while heavier elements (like tungsten and xenon) require more neutrons to remain stable, resulting in ratios greater than 1.
Nuclide notation expresses atomic information compactly. It includes the element’s symbol, atomic number (Z), mass number (A), and charge. For ions, the charge is calculated by subtracting electrons from protons. If electrons are fewer, the atom is positively charged (a cation); if more, it’s negatively charged (an anion).
For example, manganese with 25 protons and 24 electrons has a +1 charge. Rhodium with 45 protons and only 43 electrons is +2. In contrast, iodine with an extra electron becomes a -1 anion. If no mass number is given, a common isotope is assumed, as with berkelium (Bk), whose common isotope has mass 247.
Understanding isotopes and ion notation is critical in nuclear chemistry, radioactivity, and analytical techniques like mass spectrometry, as they help identify atoms, determine their behavior, and track chemical reactions.
