The photoelectron spectra below show the energy required to remove a 1s electron from a nitrogen atom and from an oxygen atom. Which of the following statements best accounts for the peak in the upper spectrum being to the right of the peak in the lower spectrum?

• Nitrogen atoms have a half-filled p subshell.
• There are more electron-electron repulsions in oxygen atoms than in nitrogen atoms.
• Electrons in the p subshell of oxygen atoms provide more shielding than electrons in the p subshell of nitrogen atoms.
• Nitrogen atoms have a smaller nuclear charge than oxygen atoms.

A sample containing atoms of C and F was analyzed using x-ray photoelectron spectroscopy. The portion of the spectrum showing the 1s peaks for atoms of the two elements is shown above. Which of the following correctly identifies the 1s peak for the F atoms and provides an appropriate explanation?

• Peak X, because F has a smaller first ionization energy than C has.
• Peak X, because F has a greater nuclear charge than C has.
• Peak Y, because F is more electronegative than C is.
• Peak Y, because F has a smaller atomic radius than C has.

What is the electron configuration for this PES graph?

• 1s2 2s2 2p6 3s2 3p3
• 1s2 2s2 2p6 3s2 3p2
• 1s2 2s2 2p6 3s2
• 1s2 2s2 2p6 3s2 3p1

Which element is represented by this PES graph?

• phosphorus
• silicon
• aluminum
• sulfur

Which element is represented by this PES graph?

• titanium
• scandium
• calcium
• potassium

Which element is represented by this PES graph?

• scandium
• argon
• calcium
• potassium

The photoelectron spectra of the 1s electrons of two isoelectronic species, Ca2+ and Ar, are shown above. Which of the following correctly identifies the species associated with peak X and provides a valid justification?

• Ar, because its radius is smaller than the radius of Ca2+
• Ca2+, because its nucleus has two more protons than the nucleus that Ar has
• Ca2+, because its nuclear mass is greater than that of Ar
• Ar, because it has completely filled energy levels.

The complete photoelectron spectrum for an element is shown above. Which of the following observations would provide evidence that the spectrum is consistent with the atomic model of the element?

• A neutral atom of the element contains exactly two electrons.
• The element does not react with other elements to form compounds.
• In its compounds, the element tends to form ions with a charge of +1 .
• In its compounds, the element tends to form ions with a charge of +3 .

The complete photoelectron spectra of neutral atoms of two unknown elements, X and Y, are shown above. Which of the following can be inferred from the data?

• Element X has a greater electronegativity than element Y does.
• Element X has a greater ionization energy than element Y does.
• Element Y has a greater nuclear charge than element X does.
• The isotopes of element Y are approximately equal in abundance, but those of element X are not

Based on the photoelectron spectrum, which element is likely to have a filled 3p subshell?

• Argon

• Chlorine

• Sulfur

• Phosphorus