Question 1

How many valence electrons are there in an atom with the electron configuration [noble gas]ns²(n -1)d¹⁰np³? A) 2 B) 3 C) 5 D) 10 E) 15

Accepted Answer

C

Question 2

Select the correct set of quantum numbers (n, l, m_l, m_s) for the first electron removed in the formation of a cation for strontium, Sr. A) 5, 1 , 0, -½ B) 5, 1, 0, ½ C) 5, 0, 1, ½ D) 5, 1, 1, ½ E) 5, 0, 0, -½

Accepted Answer

Strontium (Sr) has an electron configuration ending in 5s^2. The first electron removed during cation formation comes from the outermost shell, which is the 5s orbital. The quantum numbers for an electron in the 5s orbital are n=5 (principal quantum number), l=0 (azimuthal quantum number for an s orbital), m_l=0 (magnetic quantum number, which is 0 for s orbitals), and m_s can be either +½ or −½ (spin quantum number). Option E correctly represents these quantum numbers for the first electron removed.

Question 3

An atom of element number 33 (As) is in its ground electronic state. Which one of the following sets quantum numbers could not apply to any of its electrons? A) n = 2 l = 1 ml = -1 m_s= +½ B) n = 3 l = 0 ml = 0 m_s = -½ C) n = 3 l = 2 ml = -2 m_s = -½ D) n = 4 l = 0 ml = 0 m_s = -½ E) n = 4 l = 2 ml = 1 m_s = +½

Accepted Answer

The element arsenic (As) has an atomic number of 33, meaning it has 33 electrons. In its ground state, the electron configuration is [Ar] 3d^10 4s^2 4p^3. The quantum numbers in option E correspond to an electron in a 4d orbital, which is not occupied in the ground state of arsenic.

Question 4

In a single atom, what is the maximum number of electrons which can have quantum number n = 4?
A) 16
B) 18
C) 32
D) 36
E) None of these choices are correct.

Accepted Answer

The maximum number of electrons in a shell is given by 2n^2. For n = 4, it is 2*(4^2) = 2*16 = 32.

Question 5

Select the correct set of quantum numbers (n, l, m_l, m_s) for the highest energy electron in the ground state of tin, Sn. A) 5, 2, -1, ½ B) 5, 2, 0, ½ C) 5, 1, 2, ½ D) 5, 1, 0, ½ E) 5, 2, 1, ½

Accepted Answer

The answer of Select the correct set of quantum numbers...

Question 6

Which of the following sublevels is filled last? 3d, 4s, 4p, 4d, 5s
A) 3d
B) 4s
C) 4p
D) 4d
E) 5s

Accepted Answer

According to the Aufbau principle, electrons fill orbitals starting from the lowest-energy level to the highest. Within the same energy level, the sublevels fill in the order: s, p, d, f. However, for elements in the fourth and higher periods of the periodic table, the 3d sublevel (which has slightly higher energy than the 4s sublevel) fills after the 4s sublevel. Therefore, the 4d sublevel is filled after the 4s sublevel, making choice D the correct answer.

Question 7

Select the correct electron configuration for Te (Z = 52). A) [Kr]5s²5p⁶4d⁸ B) [Kr]5s²5d¹⁰5p⁴ C) [Kr]5s²4d¹⁰5p⁶ D) [Kr]5s²4f¹⁴ E) [Kr]5s²4d¹⁰5p⁴

Accepted Answer

Te (Z=52) is in the fifth row of the periodic table, so we first write the electron configuration up to the 5p sublevel, which is [Kr]5s^24d^105p^4. From there, we fill in the remaining electrons: one goes to the 5p sublevel to give [Kr]5s^24d^105p^5, and the rest fill the 6s and 4f sublevels, giving [Kr]5s^24d^105p^65s^24f^14. However, since 4f is higher in energy than 5d, the 4f electrons are typically written before the 5d electrons, giving the final electron configuration of [Kr]5s^24d^105p^65s^24f^14. Of the choices provided, only option E correctly represents this electron configuration.

Question 8

In many-electron atoms, which quantum numbers specify the energy of an electron? A) n and l B) n and m_l C) l and m_l D) n and m_s E) n, l, and m_l

Accepted Answer

The energy of an electron in a many-electron atom is primarily determined by its principal quantum number (n) and its angular momentum quantum number (l). The magnetic quantum number (m) does not directly determine the energy, but rather determines the orientation of the electron's angular momentum vector in space. The spin quantum number (s) also does not directly determine the energy, but rather describes the intrinsic angular momentum of the electron.

Question 9

Which one of the following statements about atomic structure and quantum numbers is incorrect? A) In a given atom, the maximum number of electrons having principal quantum number n = 3, is 18. B) The number of orbitals in a given f subshell is 7. C) For n = 4, the largest possible value of l is 3. D) For n = 4, the largest possible value of m_l is 2. E) The following set of quantum numbers for a single orbital is not allowed: n = 3, l = 1, ml = -2.

Accepted Answer

The value of mS can only be +1/2 or -1/2, therefore the largest possible value of mS is not 2.

Question 10

In the ground state of an atom of silver (Ag), how many electrons will there be with the quantum number l = 1? (The n, m_l, and m_s quantum numbers may have any appropriate values.) A) 9 B) 12 C) 18 D) 24 E) 36

Accepted Answer

The answer of In the ground state of an atom...

Question 11

Energy states of atoms containing more than one electron arise from nucleus-electron and electron-electron interactions. Which of the following statements correctly describes these effects?
A) Larger nuclear charge lowers energy, more electrons in an orbital lowers energy.
B) Larger nuclear charge lowers energy, more electrons in an orbital increases energy.
C) Smaller nuclear charge lowers energy, more electrons in an orbital lowers energy.
D) Smaller nuclear charge lowers energy, more electrons in an orbital increases energy.
E) None of these choices are correct.

Accepted Answer

A larger nuclear charge (i.e. more protons in the nucleus) leads to stronger attraction between the nucleus and electrons, which lowers the energy of the atom. However, when more electrons are added to an orbital, the electron-electron repulsion increases, which raises the energy of the atom. This is known as electron-electron repulsion or Coulombic repulsion. Therefore, larger nuclear charge lowers energy, but more electrons in an orbital increase energy.

Question 12

Which one of the following statements about orbital energies is incorrect?
A) In the hydrogen atom, the energy of an orbital depends only on the value of the quantum number n.
B) In many-electron atoms the energy of an orbital depends on both n and l.
C) Inner electrons shield outer electrons more effectively than do electrons in the same orbital.
D) The splitting of sublevels in many-electron atoms is explained in terms of the penetration effect.
E) The energy of a given orbital increases as the nuclear charge Z increases.

Accepted Answer

The energy of a given orbital actually decreases as the nuclear charge Z increases. This is because the increased nuclear charge pulls the electrons closer to the nucleus, lowering their potential energy. Therefore, statement E is incorrect.

Question 13

The effective nuclear charge for an atom is less than the actual nuclear charge due to
A) shielding.
B) penetration.
C) paramagnetism.
D) electron-pair repulsion.
E) relativity.

Accepted Answer

Shielding occurs because electrons in the outermost energy level are repelled by electrons in inner energy levels, reducing the attraction the outermost electrons feel towards the nucleus. This reduces the effective nuclear charge experienced by the outermost electrons.

Question 14

"Electrons added to atomic orbitals of the same energy will remain unpaired with parallel spins until the subshell is more than half-filled" is a statement of
A) the aufbau principle.
B) Hund's rule.
C) the Pauli exclusion principle.
D) the periodic law.
E) the singularity rule.

Accepted Answer

This statement is a specific statement of Hund's rule, which states that when electrons are added to orbitals of the same energy (degenerate orbitals), they will first fill all the orbitals with unpaired spins before pairing up with opposite spins. This configuration results in the lowest energy state for the atom. However, once the subshell is more than half-filled, it becomes energetically favorable for the electrons to start pairing up in order to lower their overall energy.

Question 15

Select the correct set of quantum numbers (n, l, m_l, m_s) for the highest energy electron in the ground state of potassium, K. A) 4, 1, -1, ½ B) 4, 1, 0, ½ C) 4, 0, 1, ½ D) 4, 0, 0, ½ E) 4, 1, 1, ½

Accepted Answer

The answer of Select the correct set of quantum numbers...

Question 16

Select the correct electron configuration for Cu (Z = 29). A) [Ar]4s²3d⁹ B) [Ar]4s¹3d¹⁰ C) [Ar]4s²4p⁶3d³ D) [Ar]4s²4d⁹ E) [Ar]5s²4d⁹

Accepted Answer

The correct electron configuration for Cu (Z = 29) is [Ar] 3d^10 4s^1, which corresponds to the choice that indicates a full 3d subshell (10 electrons) and a single electron in the 4s subshell.

Question 17

The electronic structure 1s²2s²2p⁶3s²3p⁶4s²3d⁸ refers to the ground state of A) Kr. B) Ni. C) Fe. D) Pd. E) None of these choices are correct.

Accepted Answer

The answer of The electronic structure 1s²2s²2p⁶3s²3p⁶4s²3d⁸ refers to the...

Question 18

"Each electron in an atom must have its own unique set of quantum numbers" is a statement of
A) the aufbau principle.
B) the Pauli exclusion principle.
C) Hund's rule.
D) the periodic law.
E) Heisenberg's principle.

Accepted Answer

The statement is referring to the Pauli exclusion principle, which states that no two electrons in an atom can have the same set of four quantum numbers. This is because each electron must have a unique spin (the fourth quantum number), which can only be either "up" or "down."

Question 19

Which of the following electron configurations is impossible? A) 1s²2s²2p⁶3s²3p⁴ B) 1s²2s²2p⁵3s¹3p⁴ C) 1s²2s²2p⁶3s²3p⁶3d¹⁰4s² D) 1s²2s²2p⁶3s³3p⁴ E) 1s¹2s²2p⁶3s²3p⁴

Accepted Answer

The answer of Which of the following electron configurations is...

Question 20

Select the correct electron configuration for sulfur (Z = 16). A) 1s²1p⁶2s²2p⁶ B) 1s²2s²2p⁸3s²3p⁴ C) 1s²2s²2p⁸3s²3p² D) 1s²2s²2p⁶3s²3p⁴ E) 1s²2s²2p⁶3s²3d⁴

Accepted Answer

The answer of Select the correct electron configuration for sulfur...

Quiz 8: Electron Configuration and Chemical Periodicity

How many valence electrons are there in an atom with the electron configuration [noble gas]ns²(n -1) d¹⁰np³?

Select the correct set of quantum numbers (n, l, m_l, m_s) for the first electron removed in the formation of a cation for strontium, Sr.

An atom of element number 33 (As) is in its ground electronic state. Which one of the following sets quantum numbers could not apply to any of its electrons?

In a single atom, what is the maximum number of electrons which can have quantum number n = 4?

Select the correct set of quantum numbers (n, l, m_l, m_s) for the highest energy electron in the ground state of tin, Sn.

Which of the following sublevels is filled last? 3d, 4s, 4p, 4d, 5s

Select the correct electron configuration for Te (Z = 52) .

In many-electron atoms, which quantum numbers specify the energy of an electron?

Which one of the following statements about atomic structure and quantum numbers is incorrect?

In the ground state of an atom of silver (Ag) , how many electrons will there be with the quantum number l = 1? (The n, m_l, and m_s quantum numbers may have any appropriate values.)

Energy states of atoms containing more than one electron arise from nucleus-electron and electron-electron interactions. Which of the following statements correctly describes these effects?

Which one of the following statements about orbital energies is incorrect?

The effective nuclear charge for an atom is less than the actual nuclear charge due to

"Electrons added to atomic orbitals of the same energy will remain unpaired with parallel spins until the subshell is more than half-filled" is a statement of

Select the correct set of quantum numbers (n, l, m_l, m_s) for the highest energy electron in the ground state of potassium, K.

Select the correct electron configuration for Cu (Z = 29) .

The electronic structure 1s²2s²2p⁶3s²3p⁶4s²3d⁸ refers to the ground state of

"Each electron in an atom must have its own unique set of quantum numbers" is a statement of

Which of the following electron configurations is impossible?

Select the correct electron configuration for sulfur (Z = 16) .