Periodic Trends (College Board AP® Chemistry)

Exam Questions

9 mins9 questions
11 mark

Which element has the most exothermic electron affinity?

  • Mg

  • Br

  • Na

  • K

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21 mark

Which element has the smallest atomic radius?

  • Na

  • S

  • Mg

  • Cl

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31 mark

Various trends can be observed down groups and across periods in the Periodic Table. Which statement about these trends is true?

  • Ionization energy increases going down a group.

  • Atomic radius generally decreases across a period.

  • Electronegativity decreases across a period.

  • Electron affinity generally increases down a group.

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41 mark

Electrons removed

1st

2nd

3rd

4th

5th

Ionization energy / kJ mol-1

736

1450

7740

10500

13600

Successive ionization energies for an element, X, are shown in the table above.

What is the most likely formula for the ion of X?

  • X+

  • X2+

  • X3+

  • X4+

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51 mark

C (g) + e- → C- (g) EA = -121 kJ/mol

N (g) + e- → N- (g) EA = > 0 kJ/mol

The equations for the electron affinities of carbon and nitrogen are shown above.

Why is the electron affinity for C more favourable (more negative) than the electron affinity for N?

  • The electron added to carbon experiences less repulsion that the electron added to nitrogen

  • The electron added to carbon experiences a lesser effective nuclear charge than the electron added to nitrogen

  • The electron added to carbon goes into a lower electron shell than the electron added to carbon goes into

  • The electron added to carbon goes into a lower orbital than the electron added to carbon goes into

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61 mark

Which of the following identifies the most probable value for the fourth ionization energy of boron and provides the best justification?

  • 4860 kJ/mol because the electron removed during the fourth ionization is a core electron.

  • 4860 kJ/mol because the electron removed during the fourth ionization is a valence electron.

  • 25025 kJ/mol because the electron removed during the fourth ionization is a core electron.

  • 25025 kJ/mol because the electron removed during the fourth ionization is a valence electron.

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11 mark

Which of the following electron configurations represents the element with the highest electronegativity?

  • 1s22s22p3

  • 1s22s22p4

  • 1s22s22p63s2

  • 1s22s22p63s23p1

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21 mark

Consider the following ions:

S2−,Cl-, K+, Ca2+

Which of the following arranges the ions in order of increasing ionic radius?

  • Ca2+ < K+ < Cl-, < S2−

  • S2− < Cl-, < K+ < Ca2+

  • K+ < Ca2+ < Cl- < S2−

  • Cl- < S2− < Ca2+ < K+

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31 mark

Element X

Element Y

First

1313

1086

Second

3373

2353

Third

6050

4620

Fourth

8400

6223

Fifth

22800

37831

Sixth

32600

47277

The first six ionization energies for elements X and Y are shown in the table above. The units are in kJ/mol.

Based on the data in the table, which of the following correctly identifies elements X and Y, respectively?

  • Be and Mg

  • Mg and Be

  • C and Si

  • Si and C

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