SCH3U
ATOMIC STRUCTURE & PERIODIC TABLE
PRACTICE TEST
Name____________________
Part A
1. Which one of the following conclusions did Rutherford’s gold foil experiment lead to?
A. atoms are incredibly small
B. atoms are mostly empty space
C. electrons exist only in discrete energy levels
D. protons are positively charged and electrons are negatively charged
_____
2 . Isotopes of an element have different numbers of
A. protons
B. neutrons
C. electrons
D. electrons, protons and neutrons
3. Which term applies to the number of protons in an atom?
A. atomic mass
B. mass number
C. atomic mass unit
D. atomic number
4
How many neutrons does the isotope
A. 92 B. 146 C. 238 D. 7
_____
____
238
U92 have?
5. An atom of lead has an atomic number of 82 and a mass number of 207.
How many protons are in this atom of lead ?
A. 207 B. 26
C. 82
D. 125
____________
____
6. What does the period number on the periodic table represent?
A. number of protons in an atom
B. number of neutrons in an atom
C. number of valence electrons in an atom
D. number of electron shells in an atom
___
7.
A. 2
B.
3
C.
5
____
8. In the periodic table, what happens to the atomic radius as you move from left to right
across a period?
A. The radius increases.
B. The radius decreases.
C. The radius does not change appreciably.
D. The radius varies at random.
_____
9.
The above atomic model is the
A. Hard sphere model
B. Plum pudding model
C. Rutherford model
D. Bohr model
10.
Relative atomic masses are
A. are same as mass numbers
B. weighted averages of isotopes masses
C. always expressed in whole numbers
D. fixed in comparison to oxygen
____
_____
11. What was the major contribution of Niels Bohr to the current model of the atom?
A. Electrons may enter the nucleus for brief periods of time.
B. Electrons only occupy specific energy levels.
C. An electrons has a mass much smaller than the mass of a neutron.
D. The charge of an electron is negative.
___
12. The current model of the atom suggests that
A . electron clouds surround the nucleus.
B. proton clouds surround the nucleus.
C . electrons travel in definite paths around the nucleus.
D . the exact path of a moving electron can be predicted.
_____
13. The amount of energy required to remove an electron from an atom is called
A. ionization energy B. electron affinity C. atomic energy D. electronegativity
___
14. If Thomson's model of the atom were correct, then the particles in Rutherford's
experiment would have
A . bounced directly back to the source. B. been deflected to the left.
C . been deflected to the right.
D. continued in a straight line.
____
15. An unknown element has an atomic mass of 45.7 u. Which two isotopes (written from
most to least abundant) are likely the most abundant for this element?
A. 46, 45
B. 47, 46
C. 45, 46
D. 44, 45
__
16. Why did Thomson change Dalton's atomic theory?
A . Thomson had experimental evidence of atoms, and Dalton did not.
B . Thomson's discovery that atoms were made up of even smaller particles showed that part
of Dalton's theory was wrong.
C. Thomson's discovery of the nucleus showed that Dalton's plum-pudding model was
wrong.
D. none of the above
____
17. Neutrons are particles that
A. help make up the nucleus and have no charge.
B. help make up the nucleus and are positively charged.
C. are located outside of the nucleus and are negatively charged.
D. are located outside of the nucleus and have no charge.
____
18. In the cathode-ray tube experiment, a positively charged plate attracted a beam. This
showed that the beam was made of
A. molecules.
B. positively charged particles.
C. atoms.
D . negatively charged particles.
______
19. Niels Bohr was able to explain the line spectrum of
A. helium B. hydrogen C. oxygen D. neon ________________
20.
What is the mass number of this atom?
A. 1 B. 3
C. 4
D. 7
_____
21. In Bohr’s model when an electron changes its orbit from an outer orbit to a lower
orbit , energy is
A. released B. absorbed
C. unchanged
____
22.
If an atom contains exactly 79 protons, then it's an atom of _____
A. lithium
B. silver
C.
gold
D. carbon
23. Which one of the following atoms has the largest radius?
A. O B. F
C. S D. Cl
________________
____
24. Which one of the following has the smallest radius?
A) Na
B) Cl
C) P
D) Li
_____
25. Which of the following correctly lists the five atoms in order of increasing size (smallest
to largest)?
A. O < F < S < Mg < Ba
B.
F < O < S < Mg < Ba
C.
F < O < S < Ba < Mg
D.
O < F < S < Ba < Mg
_____
26. Which of the elements below has the largest electronegativity?
E) Si
F) Mg
G) P
D) S
______
27. Of the following atoms, which has the largest ionization energy?
H) Br
I) O
J) C
K) P
_____
28.
Below is an outline of the periodic table with a number of elements represented only by the
letters A to I is shown. Use these letters when answering this question.
Which of the following elements has the highest ionization energy?
A. element A
B. element H
C. element I
D. element B
29. The graph shown could represent the trend in which of the following properties?
A. atomic radius
B. ionization energy
C. electronegativity
D. electron affinity ____
30.
The following diagram is a Bohr-Rutherford diagram of one element from the periodic table
To which group and period does this element belong?
A) Period 3 group 4
B) Period 4 group 4
C) Period 3 group 1
D) Period 1 group 3
____
31.
Which of the following atoms of elements has the greatest attraction for electrons?
(a) Ge
(b) As
(c) Se
(d) Br
(e) Bi
_____
32.
A fictitious element is composed of isotopes A and B with masses of 61.9887 and 64.9846
amu, respectively. The atomic mass of the element is 64.52. What can you conclude about
the natural abundance of the two isotopes?
a. The natural abundance of isotope A must be greater than the natural abundance of isotope
B
b. The natural abundance of isotope B must be greater than the natural abundance of isotope
A
c. The natural abundances of both isotopes must be about equal
d. Nothing can be concluded about the natural abundances of the two isotopes from the
given information
____
33.
What is the approximate average mass of a hydrogen atom in this sample?
a. 6 amu
b. 2 amu
c. 1.5 amu
d. 1 amu
34. Rutherford's gold foil experiment showed that the atom is mostly empty space because
a.
b.
c.
d.
e.
some of the alpha particles were reflected right back
some of the alpha particles were deflected
most of the alpha particles went straight through the foil
all of the alpha particles went straight through the foil
all of the alpha particles were deflected
PART B-short answer questions
1. Silicon has three isotopes. From the mass of each isotope and isotopic abundance given
below, calculate the average atomic mass of silicon . Show your work including the correct
number of significant figures to get full marks( 5 marks)
isotope
atomic mass(u)
isotopic abundance(%)
Si-28
27.98
92.23
Si-29
28.97
4.67
Si-30
29.97
3.10
Average atomic mass of silicon
= 27.98 u
x 92.23
100
= 25.805954 u
=
+
+
28.97 u
1.352899 u
x
4.67
100
+
+
29.97 u
x
3.10
100
0.92907 u
28.087923 u
= 28.1 u ( based on the least precise given quantity- in this question the least precise
given quantity is the abundance which has 3 sig figs)
Note :
 you only round after the last calculation in all multi steps chemistry problems
 do not round intermediate steps- show all numbers as it appears in calculator
 round to the least precise given quantity( i.e. the least number of sig figs)
make sure your final answer has units
2.
For the following elements ,
Arrange the elements in order of increasing radius. Explain your answer using the concepts
of effective nuclear charge and shielding.
C < A<D
-Al three atoms have the same amount of electron shielding because they have the same
number of shells
C has the highest effective nuclear charge since it has the most number of protons( 18
protons) and therefore the attraction for the electrons also increases. This increased
attraction pulls the electrons closer to the nucleus resulting in a smaller atomic radius
D has the smallest effective nuclear charge since it has the least number of protons( 11)
And therefore the weakest attraction between the nucleus and the electrons resulting in a
larger atomic radius
3.
Elements A, B, C and D have atomic radii of 265 pm, 160 pm, 185 pm, and 175 pm
respectively.
(a) Which element will have the lowest ionization energy? Why?
A
-
Ionization energy decreases with increasing atomic radius
Because there is weaker attraction between the valence electron and the nucleus in a
larger atom so it requires less energy to remove an electron from a larger atom
(b) Which element-A,B, C or D will have the highest electronegativity? Why? (2 marks)
B
- Electronegativity increases with decreasing atomic radius
-Because the smaller the atom the closer is the nucleus to the bonding electrons therefore
the stronger is the attraction between the nucleus and the bonding electrons
(c) Which of the following entities- A atom or A2+ ion will have a larger size?
Why?( 2 marks)
Atom A
When an atom loses an electron to form a positive ion , the attraction between the remaining
electrons and the nucleus is increased. As a result, the electrons are drawn closer to the
nucleus and the positive ion becomes smaller
4. (a)
(b)
(c)
Bohr`s
How did Ernest Rutherford discover the nucleus of the atom?
Describe how Bohr modified Rutherford’s atomic model.
State one similarity and one difference between Rutherford’s atomic model and
atomic model
(a) Rutherford aimed positively charged alpha particles at a gold foil. He observed that most
of the alpha particles pass through the gold foil but a few of these particles were deflected
at various angles
From these observation Rutherford reasoned that an atom must have a small dense
positively charged nucleus in the center of the atom
(b) Bohr proposed that electrons only exist in certain allowed orbits around the nucleus. The
electrons do not lose energy in these allowed orbits
(c) similarity --- Both models have a small dense positively charged nucleus
Difference - In Bohr’s model the electrons can only move in certain orbits
In Rutherford’s model the electrons are moving in all orbits around the
nucleus
5.
. (a) How did Democritus reason for the existence of atoms?
•Matter could not be divided into smaller and smaller pieces forever. Eventually the
smallest possible piece would be obtained. This piece would be indivisible called
the atom
(b) Why was Thomson’s atomic model rejected?
It could not explain the observations of the Gold Foil scattering experiment done by
Rutherford