C5_L2_Ionization energy

The table above shows the first ionization energy and atomic radius of several elements. Which of the following best helps to explain the deviation of the first ionization energy of oxygen from the overall trend?

• The atomic radius of oxygen is greater than the atomic radius of fluorine.

• The atomic radius of oxygen is less than the atomic radius of nitrogen

• There is repulsion between paired electrons in oxygen’s 2p orbitals.

• There is attraction between paired electrons in oxygen’s 2p orbitals.

For element X represented above, which of the following is the most likely explanation for the large difference between the second and third ionization energies?

• The effective nuclear charge decreases with successive ionizations.

• The shielding of outer electrons increases with successive ionizations.

• The electron removed during the third ionization is, on average, much closer to the nucleus than the first two electrons removed were.

• The ionic radius increases with successive ionizations.

Which of the following correctly compares periodic properties of two elements and provides an accurate

explanation for that difference?

• The first ionization energy of Al is greater than that of B because Al has a larger nuclear charge than B does.

• The first ionization energy of F is greater than that of O because O has a higher electronegativity than F has.

• The atomic radius of Ca is larger than that of Mg because the valence electrons in Mg experience more shielding than the valence electrons in Ca do.

• The atomic radius of Cl is smaller than that of S because Cl has a larger nuclear charge than S does.

Has the lowest first-ionization energy

• Cs

• Ag

• Pb

• Br

• Se

Based on the ionization energies of element X given in the table above, which of the following is most likely the empirical formula of an oxide of element X?

• XO₂

• X₂O

• X₂O₃

• X₂O₅

The first five ionization energies of a second-period element are listed in the table above. Which of the following correctly identifies the element and best explains the data in the table?

• B, because it has five core electrons

• B, because it has three valence electrons

• N, because it has five valence electrons

• N, because it has three electrons in the p sublevel

The first five ionization energies of an unknown element are listed in the table above. Which of the following statements correctly identifies the element and cites the evidence supporting the identification?

• Na, because of the large difference between the first and the second ionization energies

• Al, because of the large difference between the third and fourth ionization energies

• Si, because the fifth ionization energy has the greatest value

• P, because a neutral atom of P has five valence electrons

Which of the following correctly identifies which has the higher first-ionization energy, Cl or Ar, and supplies the best justification?

• Cl, because of its higher electronegativity

• Cl, because of its higher electron affinity

• Ar, because of its completely filled valence shell

• Ar, because of its higher effective nuclear charge

Based on periodic trends and the data in the table above, which of the following are the most probable values of the atomic radius and the first ionization energy for potassium, respectively?

• 242 pm, 633 kJ/mol

• 242 pm, 419 kJ/mol

• 120 pm, 633 kJ/mol

• 120 pm, 419 kJ/mol

Which of the following elements has the largest first ionization energy?

• Li

• Be

• B

• C

• N