1) Draw the complete photoelectron spectra for beryllium.

2) What is the difference between the photoelectron spectra for beryllium and that of Be²⁺?

3) Is the radius of a neutral atom of helium smaller or greater than the radius of Be²⁺ ion? Explain.

Question

1) Draw the complete photoelectron spectra for beryllium.

2) What is the difference between the photoelectron spectra for beryllium and that of Be²⁺?

3) Is the radius of a neutral atom of helium smaller or greater than the radius of Be²⁺ ion? Explain.

| General Chemistry 1

Accepted Answer

1) Be: Z = 4 ⇒ 1s²2s² ⇒ 2 subshells: 1s and 2s ⇒ 2 peaks on the complete photoelectron spectra.

1s = core orbital; 2s = valence orbital:

The core orbitals have higher binding energies than valence orbitals ⇒ 1s is on the left, 2s is on the right.

The two orbitals are 2 electrons ⇒ same height

2) Be²⁺: 1s² ⇒ only one peak on the complete photoelectron spectra.

No more peak around 4 MJ.mol^-1

3) Be: Z = 4 ⇒ 4 protons

He: Z = 2 ⇒ 2 protons

Be has higher nuclear charge ⇒ electrons in Be²⁺ are closer to the nucleus than those of He

⇒ radius of Be²⁺ < radius of He

Midterm 2 - Question 2 | General Chemistry 1