Unit 1 check
Unit 1 check: Atomic Structure and Properties
10 questions from 8 lessons in Unit 1. Answer each one, and if you miss, follow the link back to where it is taught, then try again. Your score counts first tries.
Question 1 · from 1.1 · Decide and justify
A student cuts a piece of pure aluminum foil with a mass of 2.70 g. Her classmate says: "Atoms are far too small to count, so there is no way to know how many atoms are in this piece." Is the classmate right?
Which reason supports your decision?
Question 2 · from 1.2 · Calculate
Lithium, the metal in lithium-ion batteries, has two isotopes: lithium-6, of mass 6.015 amu and abundance 7.59%, and lithium-7, of mass 7.016 amu and abundance 92.41%. What is lithium's average atomic mass, in amu? Give your answer to four significant figures.
Question 3 · from 1.3 · Match
Match each molecular formula to its empirical formula.
Setup for question 4
A supplier sells potassium chloride, KCl, as pure. A student analyzes a 4.000 g sample and finds 1.852 g of chlorine in it. Pure KCl is 47.55% chlorine by mass. Assume the analysis is accurate. These numbers are a teaching example.
Question 4 · from 1.4 · Calculate
A 4.000 g sample sold as potassium chloride contains 1.852 g of chlorine. What is the mass percent of chlorine in the sample? Give your answer to four significant figures.
Setup for question 5
Titanium dioxide is the white pigment in most paint. Titanium is a transition metal, and in that pigment it is present as an ion, not as a neutral atom.
Question 5 · from 1.5 · Multiple choice
A titanium atom, atomic number 22, has the ground-state configuration [Ar]4s²3d². What is the ground-state configuration of the Ti²⁺ ion?
Setup for question 6
A student records the photoelectron spectrum of a neutral atom of an unknown element. The table lists its peaks from the highest binding energy to the lowest. These numbers are a teaching example.
| Peak | Binding energy (MJ/mol) | Relative height |
|---|---|---|
| 1 | 208 | 2 |
| 2 | 18.7 | 2 |
| 3 | 13.5 | 6 |
| 4 | 1.95 | 2 |
| 5 | 1.01 | 3 |
Question 6 · from 1.6 · Multiple choice
Using the table: which element produced this spectrum?
Question 7 · from 1.7 · Spot the error
A student explains why a sulfur atom is smaller than a magnesium atom. Tap the line with the mistake.
Question 8 · from 1.8 · Spot the error
A student works out the formula of magnesium nitride. Tap the line with the mistake.
Question 9 · from 1.1 · Calculate
How many silver atoms are in 0.350 mol of silver? Give your answer to three significant figures, typed in e-notation (6.022 × 10²³ is typed 6.022e23).
Question 10 · from 1.2 · Decide and justify
Boron has two isotopes, boron-10 (10.01 amu) and boron-11 (11.01 amu). The periodic table lists boron's average atomic mass as 10.81 amu. Which isotope is more abundant?
Which reason supports your decision?
0 of 10 answered.