Unit 8: Electron Configurations

In a ground state atom of Kr how many electrons total will have the quantum number ℓ = 2?

10

In a ground state atom of P how many electrons total will have the quantum number ℓ = 0?

6

Which of the following represents the electron configuration of P³⁻? A) 1s²2s²2p⁶3s²3p⁶ B) 1s²2s²2p⁶3s²3p³ C) 1s²2s²2p⁶3s² D) 1s²2s²2p⁶3s²3p⁶4s¹ E) 1s²2s²2p⁶3s²3p¹

A) 1s²2s²2p⁶3s²3p⁶

Which of the following is the electron configuration of a neutral Fe atom? A) 1s²2s²2p⁶3s²3p⁶4s²3d⁶ B) 1s²2s²2p⁶3s²3p⁶4s²4d⁶ C) 1s²2s²2p⁶3s²3p⁶4s²3d⁵ D) 1s²2s²2p⁶3s²3p⁶4s²4p⁶ E) 1s²2s²2p⁶3s²3p⁶4s²3d⁷

A) 1s²2s²2p⁶3s²3p⁶4s²3d⁶

Which of the following electronic transitions represents an increase in energy in a multi-electron atom? A) 4s → 3d B) 5p → 4d C) 4d → 5s D) 4f → 6s E) 5d → 6s

A) 4s → 3d

Which of the following is the electron configuration for In? A) [Kr]5s²4d¹⁰5p¹ B) [Ar]5s²4d¹¹ C) [Ar]5s²5p¹ D) [Ar]5s²4d¹⁰5p¹ E) [Kr]5s²5p¹

A) [Kr]5s²4d¹⁰5p¹

Which of the following is the electron configuration for Ba? A) [Xe]6s² B) [Rn]6s² C) [Xe]6s¹ D) [Xe]7s² E) [Rn]7s²

A) [Xe]6s²

A ground state atom of Mg could not have any electrons with which of the following configurations? A) n = 3, ℓ = 1, mℓ = 0, ms = +½ B) n = 2, ℓ = 1, mℓ = 0, ms = +½ C) n = 3, ℓ = 0, mℓ = 0, ms = +½ D) n = 2, ℓ = 0, mℓ = 0, ms = +½ E) n = 1, ℓ = 0, mℓ = 0, ms = +½

A) n = 3, ℓ = 1, mℓ = 0, ms = +½

An electron is shown to occupy a d orbital. Which of the following sets of quantum numbers can describe this electron? A) n = 3, ℓ = 2, mℓ = -2 B) n = 4, ℓ = 1, mℓ = 2 C) n = 5, ℓ = 1, mℓ = 0 D) n = 3, ℓ = 1, mℓ = -1 E) n = 4, ℓ = 3, mℓ = -3

A) n = 3, ℓ = 2, mℓ = -2

The ground state electron configuration of an Al atom is A)1s²2s²2p⁶3s²3d¹ B) 1s²2s²2p⁶3s²3p¹ C) 1s²2s²2p⁶3s²3p⁶4s²4p¹ D) 1s²2s²2p⁶3s²3p² E)1s²2s²2p¹

B) 1s²2s²2p⁶3s²3p¹

Which of the following represents the electron configuration of S⁻? A) 1s²2s²2p⁶3s²3p⁶ B) 1s²2s²2p⁶3s²3p⁵ C) 1s²2s²2p⁶3s²3p⁴ D) 1s²2s²2p⁶3s²3p³ E) 1s²2s²2p⁶3s²3p²

B) 1s²2s²2p⁶3s²3p⁵

What is the electron configuration of K⁺? A) 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶ B) 1s²2s²2p⁶3s²3p⁶ C) 1s²2s²2p⁶3s²3p⁶4s² D) 1s²2s²2p⁶ E) 1s²2s²2p⁶3s²3p⁵

B) 1s²2s²2p⁶3s²3p⁶

Which element has the ground state electron configuration [Ar]4s²3d¹⁰4p⁵? A) As B) Br C) Se D) Te E) I

B) Br

Which element has the electron configuration 1s²2s²2p⁶3s²3p⁶4s¹3d⁵? A) V B) Cr C) Mo D) Mn E) No element has this configuration

B) Cr

Which of the following electron configurations is incorrect? A) Ca [Ar]4s² B) Mn [Ar]4s²4d⁵ C) Cu [Ar]4s¹3d¹⁰ D) Ga [Ar]4s²3d¹⁰4p¹ E) Br [Ar]4s²3d¹⁰4p⁵

B) Mn [Ar]4s²4d⁵

A single electron in an orbital has quantum numbers n = 2, ℓ = 0, mℓ = 0, ms = +½. What are the quantum numbers for the next electron added to this atom? A) n = 2, ℓ = 1, mℓ = 0, ms = +½ B) n = 2, ℓ = 0, mℓ = 0, ms = -½ C) n = 2, ℓ = 0, mℓ = 0, ms = +½ D) n = 2, ℓ = 1, mℓ = 0, ms = -½ E) n = 2, ℓ = 1, mℓ = 1, ms = -½

B) n = 2, ℓ = 0, mℓ = 0, ms = -½

A ground state atom of As could not have any electrons with which of the following configurations? A) n = 3, ℓ = 1, mℓ = 0, ms = +½ B) n = 4, ℓ = 2, mℓ = 0, ms = +½ C) n = 4, ℓ = 0, mℓ = 0, ms = +½ D) n = 3, ℓ = 2, mℓ = 0, ms = +½ E) n = 4, ℓ = 1, mℓ = 0, ms = +½

B) n = 4, ℓ = 2, mℓ = 0, ms = +½

Which of the orbital electron configurations is not possible? A) 2s¹ B) 3d¹⁰ C) 4p⁷ D) 4f⁷ E) 2p⁶

C) 4p⁷

What is the noble gas core in the electron configuration for Ru? A) Ne B) Ar C) Kr D) Xe E) Rn

C) Kr

What is the noble gas core in the electron configuration for Sb? A) Ne B) Ar C) Kr D) Xe E) Rn

C) Kr

Which pair of elements have the same valence electronic configuration of np³? A) O and Se B) Ge and Pb C) P and Sb D) K and Mg E) Al and Ga

C) P and Sb

What is the electron configuration of Co²⁺? A) 1s²2s²2p⁶3s²3p⁶3d⁵ B) 1s²2s²2p⁶3s²3p⁶4s²3d⁵ C) 1s²2s²2p⁶3s²3p⁶4s²3d⁹ D) 1s²2s²2p⁶3s²3p⁶3d⁷ E) 1s²2s²2p⁶3s²3p⁶3d⁹

D) 1s²2s²2p⁶3s²3p⁶3d⁷

Of the following, which sublevel is filled last? A) 3d B) 4s C) 4p D) 4d E) 5s

D) 4d

In a multi-electron atom, which orbital will have the highest energy? A) 4s B) 4p C) 4d D) 4f E) All are equal

D) 4f

Which element has the electron configuration 1s²2s²2p⁶3s²3p⁶4s²3d⁵? A) Fe B) Tc C) Cr D) Mn E) Mo

D) Mn

Which electron configuration violates Hund's rule? A) [He]2s²2px²2py²2pz¹ B) [He]2s²2px²2py¹2pz² C) [He]2s²2px¹2py²2pz² D) [He]2s²2px²2py² E) [He]2s²2px¹2py¹2pz²

D) [He]2s²2px²2py²

A single electron in an orbital has quantum numbers n = 3, ℓ = 0, mℓ = 0, ms =-½. What are the quantum numbers for the next electron added to this orbital? A) n = 3, ℓ =1, mℓ = 0, ms = +½ B) n = 3, ℓ = 0, mℓ = 0, ms = -½ C) n = 3, ℓ = 1, mℓ = 0, ms = -½ D) n = 3, ℓ = 0, mℓ = 0, ms = +½ E) n = 3, ℓ = 1, mℓ = 1, ms = +½

D) n = 3, ℓ = 0, mℓ = 0, ms = +½

A single electron in an orbital has quantum numbers n = 3, ℓ = 1, mℓ = 0, ms =-½. Which of the following is an acceptable set of quantum numbers for the next electron added to this orbital? A) n = 3, ℓ = 1, mℓ = 0, ms = +½ B) n = 3, ℓ = 2, mℓ = 0, ms = -½ C) n = 3, ℓ = 1, mℓ = 1, ms = +½ D) n = 3, ℓ = 1, mℓ = -1, ms = -½ E) n = 3, ℓ = 0, mℓ = 0, ms = +½

D) n = 3, ℓ = 1, mℓ = -1, ms = -½

Which of the following sets of quantum numbers represents an electron with the highest energy in a multi-electron atom? A) n = 4, ℓ = 0, mℓ = 0 B) n = 3, ℓ = 2, mℓ = -1 C) n = 3, ℓ = 1, mℓ = 0 D) n = 2, ℓ = 1, mℓ = -1 E) n = 4, ℓ = 1, mℓ = 1

E) n = 4, ℓ = 1, mℓ = 1

What quantum mechanics principle states that electrons are added to atomic orbitals with the same energy so that each orbital is singularly occupied with electrons having the same spin?

Hund's rule

hund's rule

electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible

valence electrons

electrons occupying the outermost shell

main group elements

elements in the s and p blocks; electrons are those with the highest n level

transition elements/metals

elements whose d orbitals are partially occupied

inner transition metals

elements with the last electron in an f orbital

how are electrons removed from ions?

in the reverse order that they were added (highest ns first and then (n-1)d or (n-2)f)

aufbau principle

states that each electron occupies the lowest energy orbital available

electron configuration

the arrangement of electrons in an atom

how can electron configurations be abbreviated?

write the preceding noble gas and then all of the configurations for the current row