Answer the following questions relating to the elements gallium and arsenic. First Ionization Energy — Atomic Structure Chemistry Question
Problem Context
Answer the following questions relating to the elements gallium and arsenic.
First Ionization Energy (kJ/mol): Gallium = 580, Arsenic = 950
Second Ionization Energy (kJ/mol): Gallium = 1,980, Arsenic = 1,800
Model Answer
1s²2s²2p6s²3p6s²3d¹⁰4p¹, or [Ar]4s²3d¹⁰4p¹. One point is earned for correct configuration. || 1s²2s²2p6s²3p6s²3d¹⁰4p³, or [Ar]4s²3d¹⁰4p³. One point is earned for correct configuration.
Model Answer
The electron ionized from As experiences a higher nuclear charge than the electron ionized from Ga, simply because the As nucleus has two more protons than the Ga nucleus. One point is earned for the correct explanation. || The second electron removed from Ga comes from the 4s subshell, which is lower in energy compared to the second electron removed from As, which comes from the 4p subshell. One point is earned for the correct explanation.
Model Answer
As3+. One point is earned for correct identification of the ion. || Ga+ would be larger; the outer electrons in the Ga+ ion are held less tightly because the Ga nucleus has fewer protons than the As nucleus, resulting in a larger ion. One point is earned for the correct choice with a correct explanation.
Model Answer
Trigonal bipyramidal Lewis structure with As central, 5 F atoms attached. One point is earned for the correct Lewis structure. || No; the structure is trigonal bipyramidal, so the angle between the axial F and equatorial F is 90°, the angle between equatorial F's is 120°, and the angle between axial F's is 180°. One point is earned for the correct response with explanation.