IB chemistry
Units 1-3 review
Quantitative chemistry
Significant figures
The mole- be able to convert to number of particles and mass
Finding empirical and molecular formulas from mass percentage
States of matter (know how potential and kinetic energy change in a change of state)
Chemical equations (reactants products)
Balance chemical equations
Stoichiometry- be able to covert moles in a chemical reaction
Limiting reactants
Theoretical yield and percent yield
Gases- be able to use the molar volume of a gas (22.4 dm3 per mole at STP)
Gas laws
Ideal gas law: PV=nRT
Solutions: solute, solvent, concentration, and titrations
Atomic structure
Subatomic particles- know their location and charge
Atomic number
Mass number
Nuclear symbol
Nucleus
Ions- cations, anions
Isotopes
The mass spectrometer
Finding relative atomic mass using percentages
Electromagnetic spectrum- wavelengths, frequency, energy
Line emission spectrums
Ground state
Excited states
Electron configuration
Remember the exceptions (Cu and Cr)
Finding valence electrons (group 1 has 1, group 2 has 2, group 13 has 3, group 14 has 4, group 15 has 5, etc)
Periodicity
The periodic table
Effective nuclear charge
Atomic radius
Ionic radius
Ionization energy
Electronegativity
Melting points
Reactivity of metals –increases as you go down a group
Reactivity of nonmetals- increases as you go up a group
Metals in water form metal hydroxides (OH) and hydrogen
Metal oxides in water from metal hydroxides
Nonmetal oxides in water form acids (H in front of the nonmetal)
Practice Questions
Multiple choice (paper 1)
1. The simplest formula for a hydrocarbon that is 20.0 percent hydrogen by mass is
a. CH
b. CH 2
c. CH 3
d. C 2 H 2
e. C 2 H 5
2. 3 Cu + 8 HNO 3  3Cu(NO 3 ) 2 + 2NO + 4H 2 O
Copper reacts with dilute nitric acid according to the following reaction. If 2 moles of copper metal are allowed
to react with excess nitric acid, how many grams of NO gas can be formed?
a. 90.0 g
b. 80.0 g
c. 40.0 g
d. 20.0 g
e. 1.5 g
3. Which pair of atoms represents nuclei that have the same number of neutrons?
a. 56 Co and 58Co
b. 57Mn and 57Fe
c. 58Ni and 57 Fe
d. 58Ni and 57Co
e. 59 Ni and 56 Fe
4. How many valence electrons does arsenic have?
a. 3
b. 4
c. 5
d. 6
e. 7
5. Which element has the largest atomic radius?
a. B
b. Al
c. Ga
d. In
e. Tl
6. Which of the following properties generally decreases across the periodic table from sodium to chlorine
a. First ionization energy
b. Atomic mass
c. Electronegativity
d. Atomic radius
7. The effective nuclear charge experienced by the outermost electron of Na is different than the effective nuclear
charge experienced by the outermost electron of Ne. This difference best accounts for which of the following?
a. Na has a greater density than Ne.
b. Na has lower first ionization energy than Ne.
c. Na has a higher melting point than Ne.
d. Na has a higher neutron-to-proton ratio than Ne.
e. Na has fewer naturally occurring isotopes than Ne.
8. The first ionization energy for magnesium is 730 kJ/mol. The third ionization energy for magnesium is 7700
kJ/mol. What is the most likely value for magnesium’s second ionization energy?
a.490 kJ/mol b. 1400 kJ/mol
c. 4200 kJ/mol
d. 7100 kJ/mol e. 8400 kJ/mol
9. Which of the following statements is true regarding sodium and chlorine?
a. sodium has greater electronegativity and larger first ionization energy
b. chlorine has a larger atomic radius and a larger first ionization energy
c. chlorine has greater electronegativity and a larger atomic radius
d. chlorine has greater electronegativity and a larger first ionization energy
e. sodium has larger first ionization energy and a larger atomic radius
10. Identify the element with a 1+ charge and 10 electrons?
a. Na
b. Mg
c. F
d. Ne
11. How many significant figures should the result of the following calculation have?
(0.04500)(2.002)(38.26 – 1.2)
a. 1
b. 2
c. 3
d. 4
e. 5
12. 100.0 cm3 of a 0.50 mol dm-3 solution of BaCl 2 is added to a 50.0 cm3 of a 0.10 mol dm-3 solution of Na 2 SO 4 . A
precipitate of BaSO 4 is formed according to the equation below.
BaCl 2 (aq) + Na 2 SO 4 (aq)  BaSO 4 (s) + 2NaCl(aq)
What is the amount, in mol, of BaSO 4 produced?
a. 0.0050
b. 0.010
c. 0.050
d. 0.10
13. Which species have the same electron configuration?
I.
O2-, F-, Ne
II.
Li+, Na+, K+
III.
S2-, Ar, K+
a. I and II only
b. I and III only
c. II and III only
d. I, II, and III
14. For which element are the group number and period number the same?
a. Li
b. Be
c. B
d. Mg
15. Which of the reactions below occur as written?
i. Br 2 + 2I-  2 Br- + I 2
ii. Br 2 + 2Cl-  2 Br- + Cl 2
a. i only
b. ii only
c. both i and ii
d. neither i or ii
16. What amount of oxygen, O 2 , (in moles) contains 1.8 x 1022 molecules?
a. 0.0030
b. 0.030
c. 0.30
d. 3.0
17. The diagram represent the emission spectrum of hydrogen. Groups of arrows are labelled W, X, and Y
Which statement is correct?
a. The arrow represent the transition of electrons to different energy levels when heat is supplied
b. The arrows W represent emission in the UV region
c. The smallest arrow of X represents a violet line in the emission spectrum
d. The arrows Y represent emission of electromagnetic waves with higher energy than those represented by
X and W
18. The horizontal axis of the bar chart represents the elements of period 3 from sodium to chlorine (excluding Si).
What could be the vertical axis represent?
a.
b.
c.
d.
Melting point of the element
Electronegativity of the bonded atom
Ionic radius of the most common ion
First ionization energy in the gaseous state
19. How many electrons does 31P3- contain?
a. 12
b. 15
c. 16
d. 18
20. When the following reaction is balanced, what is the coefficient for iron?
Fe + O 2  Fe 2 O 3
a. 2
b. 3
c. 4
d. 5
21. 15.00 g of magnesium oxide, MgO, when heated, produced 1.02 g of magnesium, Mg. Which is the correct
expression for the percentage yield of magnesium?
2MgO  2Mg + O 2
a. 15.00 x 2 x 100 / 1.02
b. 15.00 x 40.3 x 100 x 1.02/ 40.3
c. 1.02 x 40.3 / ( 15.00 x 24.3)
d. 1.00 x 40.3 x 100 / (15.00 x 24.3)
22. Four identical containers under the same conditions are filled with gases as shown below. Which container and
contents have the highest mass?
B
23. Wave A has a wavelength = 1.2 x 102 m and wave B has a wavelength = 1.4 x 10-2 m. Which wave has the most
energy?
a. Wave A
b. wave B
c. they have the same amount
d. unable to determine
Free response (paper 2)
1. Answer the following questions about the element selenium, Se (atomic number 34)
a. Samples of natural selenium contain six stable isotopes. In terms of atomic structure, explain what these
isotopes have in common, and how they differ.
Same number of protons but different number of neutrons
b. In terms of atomic structure, explain why the first ionization energy of selenium is
i.
Less than that of bromine (atomic number 35) and
The ionized electron in both Se and Br are in the same energy level but Br has more protons than Se
so the attraction to the nucleus is greater
ii.
Greater than that of tellurium (atomic number 52).
The electron removed from Te is in the 5th energy level while the electron removed from Se is in the
4th energy level. It requires more energy because it is closer to the nucleus (higher effective nuclear
charge)
2. Explain why the atomic radius of Li is larger than that of Be.
Li and Be have the same energy levels but Li has less protons so they feel a smaller effective nuclear charge
therefore it is bigger
3. Write the electron configuration for Cu and Cu2+
Cu: [Ar]4s13d10
Cu2+: [Ar] 3d9
4.
a. Describe the process occurring at stage Q and stage S
Q: ionization
S: deflection by magnetic field
b. Define the term relative atomic mass.
Average mass of all isotopes taking into account the abundance
c. Calculate, showing your working, the relative atomic mass of magnesium, giving your answer to two
decimal places
24.32
5. A. State the number of protons, electrons, and neutrons in the ion 15 7 N3P: 7
e: 10
n: 8
6. State and explain the trends in the atomic radius and the ionization energy
a. For the alkali metals Li to Cs
Radius increases: as you go down the group, there more energy levels are added to the atom
Ionization energy decreases: bigger atoms don’t hold on to their electrons as well so it is easier to
remove
b. For period 3 elements Na to Cl
Radius decreases: same number of energy levels but more protons to pull electrons in tighter
Ionization energy increases: smaller atoms hold onto their electrons better to they are harder to remove
7. Write an equation for each reaction between water and
a. Sodium oxide
Na 2 O + H 2 O  2NaOH
b. Sulfur dioxide
SO 2 + H 2 O  H 2 SO 3
8. When a small quantity of strongly smelling gas such as ammonia is released into the air, it can be detected
several meters away in a short time.
a. Use the kinetic molecular theory to explain why this happens.
Gas molecules move very quickly and spread through the air
b. State and explain how the time taken to detect the gas changes when the temperature is increased
Less time, increased temperatures increases the speed of the molecules and they spread out more
quickly.
9. 27. 82 g of hydrated sodium carbonate crystals, Na 2 CO 3 ·xH 2 O, was dissolved in water and made up to 1.000
dm3. 25.00 cm3 of this solution was neutralized by 48.80 cm3 of hydrochloric acid of concentration 0.100 mol
dm-3. Na 2 CO 3 + 2HCl 2NaCl + H 2 O + CO 2
a. Calculate the molar concentration of the sodium carbonate neutralized by the hydrochloric acid
0.096 mol dm-3
b. Determine the mass of sodium carbonate neutralized by acid and hence the mass of sodium carbonate
present in 1.000 dm3 of solution.
10.36 g
c. Calculate the mass of water in the hydrated crystals and hence find the value of x.
17.46 g of water so x = 10
10. Airbags are an important safety features in vehicles. Sodium azide, potassium nitrate, and silicon dioxide have
been used in one design of airbag. Two students looked at data in a simulated computer-based experiment to
determine the volume of nitrogen generated in an airbag. Sodium azide, a toxic compound, undergoes the
following decomposition reaction under certain conditions. 2NaN 3 (S)  2Na(s) + 3N 2 (g)
Using the simulation program, the students entered the following data into the computer.
Temperature ( ᴼC)
Mass of NaN 3 (s) (kg)
Pressure (atm)
25.00
0.0650
1.08
a. State the number of significant figures for the temperature, mass, and pressure data.
Temp: 4
mass: 3
pressure: 3
b. Calculate the amount, in mol, of sodium azide present
0.00100 mol
c. Determine the volume of nitrogen gas, in dm3, produced under these conditions based on this
reaction. 0.0340 dm3