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

This course has no free-response prompt tagged to this unit, so one from elsewhere in the course is used. It is still worth writing — the skill transfers.

A student titrates 25.00 mL of a solution of an unknown monoprotic weak acid HA with 0.150 M NaOH. The equivalence point occurs after 32.00 mL of titrant has been added. When 16.00 mL of NaOH has been added, the measured pH is 4.65.

Calculate the moles of HA originally present and its initial molarity.

Determine the Ka of HA, and explain why the pH at 16.00 mL gives this information directly.

Predict whether the pH at the equivalence point is above, below, or equal to 7.00, and justify your answer with a chemical equation.

Explain which of phenolphthalein (transition range 8.3–10.0) or methyl red (transition range 4.4–6.2) is the better indicator for this titration.

Describe the effect on the calculated molarity of HA if the student had rinsed the burette with distilled water and left it wet before filling it with NaOH.