The following are electron configurations for three different neutral atoms. Name each element

Question

and indicate whether the atom is in the ground state or in the excited state.
a) 1s2 2s2 2p6 3s2 3p3 4s1
b) 1s2 2s2 2p6 3s2 3p6 4s2 3d1
c) 1s2 2s2 2p6 3s2 3p6 4s2

Answer 1

To identify the elements and their states (ground or excited), we need to analyze each provided electron configuration.

a) 1s² 2s² 2p⁶ 3s² 3p³ 4s¹

• This configuration corresponds to the element with atomic number 33, which is Arsenic (As).
• In this configuration, an electron from the 4s subshell is excited into the 3p subshell (which already contains 3 electrons), indicating that this atom is in an excited state.

b) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹

• This configuration corresponds to the element with atomic number 21, which is Scandium (Sc).
• All electrons are in their respective subshells according to the Aufbau principle, meaning that this atom is in the ground state.

c) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

• This configuration corresponds to the element with atomic number 36, which is Krypton (Kr).
• This configuration is also completely filled according to the Aufbau principle, indicating that this atom is in the ground state.

In summary: a) Arsenic (As), excited state
b) Scandium (Sc), ground state
c) Krypton (Kr), ground state