C) [Ar]3d^6 4s^23d^3 6) Which reaction below represents the electron affinity of S? A) S^-(g) S(g) + e B) S^-(g) + e^82-(g) C) S(g) + K^st(g) + e D) S^2-(g) = S(g) + e E) S(g) + e S^-(g) Which of the following is a correct set of quantum numbers for an orbital? A) n = 3, l = 7, m = -3 B) n = 3, l = 1, m = +2 C) n = 3, l = 2, m = 1
The Correct Answer and Explanation is:
Let’s go through each question step by step:
Question 1: Electron Configuration of Sulfur (S)
You provided an electron configuration, [Ar] 3d^6 4s^2 3d^3, but this is incorrect for sulfur. The correct electron configuration for sulfur (atomic number 16) is:
S:1s22s22p63s23p4\text{S}: 1s^2 2s^2 2p^6 3s^2 3p^4S:1s22s22p63s23p4
Sulfur has 16 electrons, so its electron configuration follows the Aufbau principle, filling the lower energy orbitals first. The correct arrangement is:
- 1s^2 (2 electrons)
- 2s^2 (2 electrons)
- 2p^6 (6 electrons)
- 3s^2 (2 electrons)
- 3p^4 (4 electrons)
Question 2: Electron Affinity of Sulfur (S)
Electron affinity is defined as the energy released when an electron is added to a neutral atom in the gas phase. The correct reaction that represents the electron affinity of sulfur is:
E) S(g) + e⁻ → S⁻(g)
This is the correct representation of an atom (S) gaining an electron to form an anion (S⁻). The other options involve incorrect species or reactions that do not represent electron affinity.
- A) Incorrect because the reaction describes the dissociation of an anion (S⁻) into an atom (S) and an electron, which is the opposite of electron affinity.
- B) Incorrect as it involves a negative ion (S⁻) gaining an electron, which is not an electron affinity process.
- C) Incorrect because it involves potassium (K) and sulfur, which is unrelated to sulfur’s electron affinity.
- D) Incorrect because it involves the formation of S²⁻, which would relate to an electron affinity step that would involve two electrons.
Question 3: Correct Quantum Numbers
Quantum numbers describe the properties of atomic orbitals. The correct set of quantum numbers from the choices is:
C) n = 3, l = 2, m = 1
Explanation:
- n = 3: This is the principal quantum number, which determines the energy level of the orbital.
- l = 2: This is the azimuthal (angular momentum) quantum number. It indicates the type of orbital (0 = s, 1 = p, 2 = d, 3 = f). For l = 2, this corresponds to a d orbital.
- m = 1: This is the magnetic quantum number, which determines the orientation of the orbital. For a d orbital (l = 2), m can range from -2 to +2, so m = 1 is valid.
Let’s look at why the other choices are incorrect:
- A) n = 3, l = 7, m = -3: This is not possible because l must be between 0 and n-1, so l = 7 is invalid for n = 3.
- B) n = 3, l = 1, m = +2: This is not valid because when l = 1 (a p orbital), m can only range from -1 to +1, so m = +2 is invalid.
Thus, the correct set of quantum numbers is C) n = 3, l = 2, m = 1.
Summary:
- Electron Configuration for S: Correct configuration is [Ne] 3s² 3p⁴.
- Electron Affinity for S: The correct reaction is E) S(g) + e⁻ → S⁻(g).
- Correct Quantum Numbers: The correct set is C) n = 3, l = 2, m = 1.
