Onstudy SCH3U Unit 1 Practice Test

Unit 1 Practice Test – Matter, Chemical Trends, and Chemical Bonding

Section A – Multiple Choice (K/U, 15 marks)

1. Who proposed that electrons exist in specific energy levels?
a. Bohr d. Rutherford
b. Dalton e. Schrödinger
c. Thomson

2. The nucleus of an atom consist of which particles?

a. protons d. protons and neutrons
b. neurons and electrons e. electron, protons and
c. electrons and protons neutrons

3. Isotopes of carbon have the same number of ___________ but different

number of ____________.
a. neutrons, protons d. protons, electrons
b. protons, neutrons e. neutrons, electrons
c. electrons, protons

39
4. Which statements are true about the atom of element
19
X ?
I. The element is yttrium
II. The element has 39 protons
III. The element has 20 neutrons
IV. The element has 19 electrons

a. I and II d. I, II, and IV

b. II and III e. I, II, III, and IV
c. III and IV

5. What are the vertical columns on the periodic table called?

a. Blocks d. Actinoids
b. Groups e. Lanthanoids
c. Periods
Onstudy SCH3U Unit 1 Practice Test

6. Using the table below, determine the average atomic mass of magnesium.
Isotope Atomic mass ( Natural abundance (%)
Mg - 24 23.99 79%
Mg - 25 24.99 10%
Mg - 26 25.98 11%

a. 23. 99  d. 25.98 
b. 24.31  e. 74.96 
c. 24.98 

7. What is the relationship between the size of an atom and the

electronegativity?
a. atom size increases, electronegativity is the same
b. atom size increases, electronegativity increases
c. atom size decreases, electronegativity increases
d. atom size decreases, electronegativity decreases
e. no relationship

8. Which element will form an ionic bond with a halogen?

I. an alkali metal
II. another halogen
III. an alkaline earth metal
a. I d. II and III
b. I and II e. I, II, and III
c. I and III

9. Which are examples of molecular compounds?

I. Water, H2O
II. Fluorine gas, F2
III. Nitrogen dioxide, NO2
a. I d. II and III
b. I and II e. I, II, and III
c. I and III
Onstudy SCH3U Unit 1 Practice Test

10. The Lewis structure (dot diagram) represents an atom with

a. two protons.
b. two lone pairs of electrons.
c. two paired valence electrons.
d. two bonding pairs of electrons.
e. two unpaired valence electrons

11. Which diagram represents a polyatomic ion?

12. The electronegativity of potassium is 0.8 and the electronegativity of

chlorine is 3.2. What type of bond exists between these atoms?
a. mostly ionic
b. polar covalent
c. non-polar covalent
d. slightly polar covalent
e. none of the above
Onstudy SCH3U Unit 1 Practice Test

13. Which statement about ionization energy is false?

a. Ionization energy is the amount of energy required to remove the

outermost electron from an atom or ion in the gaseous state.
b. The ionization energies of Group 1 elements are greater than the
ionization energy of the elements in any other group
c. The second ionization energy of a given element is larger than the
first ionization energy.
d. The ionization energies of Group 18 elements are greater than the
ionization of energies of the elements in any other group.
e. Within a period, the ionization energy is largest for atoms or ions
that have a filled outer shell.

14. Which compound is an oxoacid?

a. HCl d. H2CO3
b. HBr e. NaOH
c. H2O

15. Which of the following statements about non-metals is false?

a. Group 15 elements are all non-metals.

b. The halogens are non-metals.
c. The most common elements (C,N,O) in living tissues are non-metals.
d. Non-metals are on the right end of the periodic table.
e. There are fewer non-metals than there are metals…
Onstudy SCH3U Unit 1 Practice Test

Section B – Fill in the blank / Matching Questions - (T/I, 14 marks: C, 8

marks)
16. Complete the following table by filling in either the missing chemical
formula or name. (14 marks)

CHEMICAL
FORMULA CHEMICAL NAME

Molecular Compounds

Diphosphorus pentoxide

CCl4

Binary Ionic Compounds

rubidium selenide

GaI3

gold (III) oxide

FeS

Cobalt (II) bromide

Compounds with Polyatomic Ions

ammonium hydroxide

Li2SO4

magnesium phosphate

potassium chlorite
Onstudy SCH3U Unit 1 Practice Test

Acids

hydrobromic acid

H2CO3

pernitric acid
*you’ll have to think about the ion here
😊

17. Match the term on the left with the most appropriate definition on the right. (C,
8 marks)
i. Polar Covalent A The energy that is needed to remove an electron
Bond from a neutral atom.
ii. Isotopes B A chemical bond in which two electrons are
shared by two atoms.
iii. Electron Affinity C An arrangement of eight electrons in the valence
shell of an atom.
iv. Ionization Energy D A covalent bond between atoms that have
significantly different electronegativities. This
results in the electron pair being shared
unevenly.
v. Atomic Radius E The energy absorbed or released when an
electron is added to a neutral atom.
vi. Stable Octet G The distance from the nucleus of an atom to the
approximate outer boundary of the cloud-like
region of its electrons.
vii. Covalent Bond H Atoms of an element that are chemically similar
but have different numbers of neutrons and
thus, different mass numbers.
Onstudy SCH3U Unit 1 Practice Test

viii. Electronegativity J A relative measure of an atom’s ability to attract

shared electrons in a chemical bond.

Section C – Short Answer (Communication, 6 marks)

18. What is a molecular compound? (1 marks)
________________________________________________________

________________________________________________________

19. Examine the graph below

What is the trend (from left to right) across a period? (1 marks)

_____________________________________________________________

_____________________________________________________________
Onstudy SCH3U Unit 1 Practice Test

20. a. Draw the Lewis diagram for Cl2 (1 marks)

b. How many lone pairs of electrons are in a chlorine molecule, Cl2?

(1 mark)
_______________________________________________________

c. How many bonding pairs of electrons are there? (1 mark)

_______________________________________________________

d. What type of bond exists between the two atoms? ( 1 mark)

_______________________________________________________
Section D – Application (A, )
21. Phosphorous trichloride was a precursor for insecticides and herbicides.
How many bonding pairs and lone pairs of electrons are present in the
molecule PCl3? (3 marks)

22. The differences in the properties of compounds often reflect the type of
chemical bonding in the compound and its polarity. This is especially true for
molecular compounds that are composed of similar molecules but have
different properties (i.e. different boiling and melting points). Examine the
data for the compounds CH3Cl and CH4 shown in the table below
Compound Melting point (ºC) Boling point (ºC)
CH3Cl -97.7 -24.2
CH4 -182.5 -161.5

a. Draw a Lewis structure for each molecule (2 marks)

b. Compare the polarity of the C-Cl bond and C-H bond in terms of
electronegativity difference. (4 marks)
c. Explain the difference in melting and boiling points in terms of their polarities
and intermolecular forces (4 marks)
Onstudy SCH3U Unit 1 Practice Test

ANSWER KEY
1. a, 2. d, 3. b, 4. c, 5. a, 6. b, 7. c,
8. c, 9. e, 10. e, 11. d, 12. a, 13. b, 14. D
15.a
16. P2O5, carbon tetrachloride, Rb2Se, gallium iodide, Au2O3, iron (II) sulfide,
CoBr2, NH4OH, lithium sulfate, Mg3(PO4)2, KClO2, HBr, carbonic acid, HNO4.
17. i – D; ii – H; iii- E; iv – A; v – G; vi – C; vii – B; viii – J
18. A compound made up of non-metals, held together by covalent bonds.
19. First Ionization Energy increases across a period (from left to right)

20. a. b. 6 pairs c. 1 pair d. covalent bond

21. 3 bond pairs; 10 lone pairs ( 1 lone pair on central atom P)

22. a methane chloromethane

b. For C – H bond, EN = 2.6 – 2.1 = 0.5 ∴ C-H bond is Polar Covalent (PC). However, the
bond dipoles cancel each other making the molecule of methane Non-Polar (NP). In other words,
the share of valence electrons is EVEN ∴ molecule is Non-Polar

For C-Cl bond , EN = 3.2 – 2.6 = 0.6 ∴ C-Cl bond is Polar Covalent(PC). The bond dipoles do
not cancel out, making the molecule of chloromethane Polar (P). In other words, the share of
valence electrons is UNEVEN ∴ molecule is Polar.
c. In Chloromethane, a polar molecule, London dispersion forces (weakest) and hydrogen bonding
are the intermolecular forces whereas in methane only London dispersion forces occur. This
stronger forces in chloromethane are responsible for the higher melting and boiling points
compared to those of methane.