Unit 1: Atomic Structure & Properties
Chemistry · Unit 1 · Paper 2

Atomic Structure & Properties unit test

A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.

Paper 1Paper 2Paper 3
Each paper is built from this unit’s 21 terms and is the same for everyone, so a teacher can assign “Unit 1, Paper 2” and every student sits the identical test. Multiple choice is marked objectively; the written sections you mark yourself against the model answer and rubric.
Suggested time 37 min 34 points0/17 attempted
1

Shielding

2

Isotopes

3

Effective nuclear charge (Zeff)

4

Percent composition

5

Absorption and emission spectra

6

Average atomic mass

7

Coulomb's law in atoms

8

Ionic radius

9

Valence electrons

10

Photon energy

11

Atomic radius trend

12

Photoelectron spectroscopy

Short answer 1. Define or explain: Electronegativity

3 pts

Short answer 2. Define or explain: Empirical vs molecular formula

3 pts

Short answer 3. Define or explain: Why the first ionization energy of oxygen is below nitrogen

3 pts

Short answer 4. Define or explain: Ionization energy trend

3 pts

Free response

10 pts

Answer the following questions about the alkali metals and their compounds. Element Atomic radius (pm) First ionization energy (kJ/mol) Li 152 520 Na 186 496 K 227 419 Rb 248 403 Lattice enthalpies (kJ/mol): LiF 1036, NaF 923, KF 821, NaCl 787.

(a) Describe the trend in atomic radius down group 1, and explain it in terms of atomic structure.

(b) Explain the trend in first ionization energy down group 1 using Coulomb’s law.

(c) Write the balanced equation for the reaction of potassium metal with water, including states.

(d) Predict whether rubidium reacts more or less vigorously with water than potassium, and justify your prediction.

(e) Explain why the lattice enthalpy of LiF is greater than that of NaF.

(f) Explain why the lattice enthalpy of NaF is greater than that of NaCl.

(g) Predict which compound, NaF or NaCl, has the higher melting point, and justify your prediction.

(h) A 0.500 g sample of an alkali metal M reacts completely with excess water to produce 0.0109 mol of H₂. Determine the molar mass of M and identify the metal.

(i) Explain why alkali metals are stored under oil rather than in air.

(j) Solid NaCl does not conduct electricity but molten NaCl does. Explain this difference in terms of structure.