How do the following properties change down Group 17 of the periodic table?

C

85 % of the candidates know the trends in ionization energy and ionic radius down Group 17. The other distractors were equally chosen by the remainder of the candidates.

Which ion has the largest radius?

A.  Na⁺

B.  Mg²⁺

C.  P³⁻

D.  S²⁻

C

Which property increases down group 17, the halogens?

A. Electron affinity

B. Boiling point

C. First ionization energy

D. Reactivity

B

X, Y and Z represent the successive elements, Ne, Na and Mg, but not necessarily in that order.

What is the order of increasing atomic number?

A.     X < Y < Z

B.     X < Z < Y

C.     Y < Z < X

D.     Y < X < Z

A

What is the order of decreasing ionic radius?

A.     S²⁻ > Cl⁻ > Al³⁺ > Mg²⁺

B.     Cl⁻ > S²⁻ > Al³⁺ > Mg²⁺

C.     S²⁻ > Cl⁻ > Mg²⁺ > Al³⁺

D.     Mg²⁺ > Al³⁺ > Cl⁻ > S²⁻

C

Which are the most reactive elements of the alkali metals and halogens?

A.  Lithium and fluorine

B.  Lithium and iodine

C.  Caesium and fluorine

D.  Caesium and iodine

C

70% of candidates selected the most reactive alkali metal and halogen. The most commonly chosen distractor was lithium and fluorine.

Which electron configuration is that of a transition metal atom in the ground state?

A. [Ne]3s²3p⁶4s¹

B. [Ar]3d⁹

C. 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p²

D. [Ar]4s¹3d⁵

D

Which describes an atom of bismuth, Bi (Z = 83)?

C

A well answered question regarding finding principal energy level and valence electrons from position on the periodic table.

Which correctly describes the reaction between potassium and excess water?

A. The reaction is endothermic.

B. The final products of the reaction are potassium oxide and hydrogen.

C. The final products of the reaction are potassium hydroxide and hydrogen.

D. The final pH of the solution is 7.

C

Which series represents atoms in order of decreasing atomic radius?

A. N > C > Be > Mg

B. Mg > N > C > Be

C. Be > C > N > Mg

D. Mg > Be > C > N

D

Another well answered question with 75 % correctly ranking elements according to atomic radii. One G2 form stated that this question was repeated in paper 2.

What is the correct order for increasing first ionization energy?

A.  Na < Mg < Al

B.  Na < Al < Mg

C.  Al < Mg < Na

D.  Al < Na < Mg

B

The majority of candidates focussed on the general trend of ionization energy increasing across the period and missed out the finer details due to sub-levels. The correct order for increasing first ionization energy was Na < Al < Mg rather than Na < Mg < Al.

What is the correct trend going down groups 1 and 17?

A. Melting points increase

B. Boiling points decrease

C. Electronegativities increase

D. Ionization energies decrease

D

Most candidates selected ionization energy as the property that decreases down both group 1 and 17.