ELEMENTS – THE STORY SO FAR…
CLASS ASSESSMENT TASK
<YOUR NAME HERE>
 Save this file to your computer, home drive or memory stick.
 Complete the questions (answer in full sentences wherever possible).
 Leave the questions in the document but feel free to delete these instructions and change other
formatting like fonts.
 Add diagrams, photos or pictures where appropriate.
 Complete the self-assessment on the last page
 Print your document when complete, staple and submit.
You will have 5 lessons to complete this assessment task.
ATOMIC NUMBER AND MASS
1
Using your knowledge of isotopes and a copy of the periodic table, copy and complete the following table and fill in the
missing gaps.
Isotope Symbol
13
6
Isotope name
Atomic Number
of element
Number of
Protons
Number of
Neutrons
10
30
Number of
electrons (in
uncharged atom)
C
Oxygen-16
36
30
29
34
ELECTRON CONFIGURATION
2
a For the Bohr model of the atom, what is the maximum number of electrons that the fourth electron shell can contain?
b What letter of the alphabet is used to name this shell?
3 A potassium atom contains 19 protons.
a How many electrons will be present in an uncharged potassium atom? Justify your answer.
b What is the electronic configuration of a potassium atom according to the Bohr model?
c From the electronic configuration of potassium, it is clear that electrons do not normally occupy the fifth shell. What
could be done to potassium atoms for electrons to jump into this shell? Explain.
SUMMARY – WHAT ARE ELEMENTS MADE OF?
Remember
4 Where are each of the following particles found in an atom and what are their charges?
a protons
b neutrons
c electrons
5 When an atom is uncharged, what is true of the number of protons and electrons present?
6 State the symbol for:
a atomic number
b mass number
c the second shell from the nucleus in the Bohr model of the atom
Understand
7 Distinguish between an atom and an element. Give an example to illustrate your point.
8 Explain why the mass numbers of isotopes are exact whole numbers but the relative masses of all atoms, except atoms of
the carbon-12 isotope, are not exact whole numbers.
9 Element 22 in the periodic table, titanium, has five naturally occurring isotopes. What will the atoms of titanium have in
common and in what way(s) will they be different?
Apply
10
235U
92
is a radioactive isotope of uranium that is used in nuclear reactors.
a
b
c
d
How many protons are present in an atom of this isotope?
How many neutrons are present in an atom of this isotope?
How many electrons are present in an uncharged atom of this isotope?
Only 0.7% of the uranium atoms in naturally occurring uranium exist as this isotope. The other isotopes present are
uranium-234 (0.01%) and uranium-238 (99.3%). Write the symbols for these two isotopes.
11 According to the Bohr model of the atom, the electronic configuration of the uncharged atoms of a certain element is 2,
8, 8.
a What is the atomic number of the element?
b What element must it be?
c What will be the electronic configuration of the next element on the periodic table? State your reasoning.
Analyse
12 Element number 52, tellurium, has a relative atomic mass of 127.6 amu, correct to 1 decimal place. The mass numbers
of its naturally occurring isotopes are 120, 122, 123, 124, 125, 127, 128 and 130. The next element, iodine, has a relative
atomic mass of 126.9 amu, correct to 1 decimal place. It only has one naturally occurring isotope, which has a mass
number of 127.
a Write the symbol for tellurium-127 and for iodine-127.
b Explain why the atoms of these two different elements can have the same mass number.
Create
13 Create drawing/diagram that shows the models of the atom, from the original theory that it was a solid sphere, as
proposed by the English chemist John Dalton, to the Bohr model. Use the Internet to find images of the scientists involved
and place copies onto your poster. Investigate the year in which each model was proposed and show a timeline on your
chart. MAXIMUM 1 A4 page
THE PERIODIC TABLE
14 Briefly outline the contribution Dmitri Mendeleev made to chemistry.
15 Add the missing words: When the periodic table was first developed, the elements were listed in order of increasing
_________________________________________. They were placed in vertical columns called
__________________________ with other elements that had similar ________________________________
______________. Now the elements are listed in order of increasing _________________________________.
16 Explain why hydrogen was placed in group 1 even though it does not have similar properties to the rest of the group.
17 a Name the element that is located in group 17, period 5.
b Outline two facts you can deduce about the electronic configuration of uncharged atoms of this element from its
position in the periodic table.
18 a Write the electronic configuration of the first three elements in group 2 of the periodic table.
b Identify the pattern in these electronic configurations.
TYPES OF ELEMENTS
19 What are the main properties of metals?
20 What is the difference between a metal and a metalloid?
21 Name two properties shown by some transition metals that are not shown by group 1 or 2 metals?
22 Predict some of the properties of the element rubidium and state your reasoning.
SUMMARY – CLASSIFYING ELEMENTS
Remember
23 What is the name given to the following features of the periodic table?
a a horizontal row
b a vertical column
c the set of 10 groups from group 3 to group 12
24 State the group number of the following sets of elements:
a alkaline earth elements
b halogens
c noble gases
d alkali metals
25 What is a valence shell?
26 a State the features that elements in the same group have in common.
b State the features that elements in the same period have in common.
Understand
27 Give explanations for the following.
a Hydrogen was placed in the same group as a set of metals, even though it is a non-metal.
b Helium was placed in the same group as the noble gases, even though its uncharged atoms have a different number
of electrons in the valence shell to those of the other group members.
28 An inert substance is one that will not react with any other substance. Originally, group 18 elements were known as the
‘inert gases’. Suggest why the name was changed to ‘noble gases’.
Apply
29 Only two elements are liquids at room temperature—bromine and mercury. Bromine is a non-metal and mercury is a
metal. In what ways are these two liquids likely to appear and behave differently from each other? Discuss.
30 The experiment conducted by Ernest Rutherford in which alpha particles were fired at a thin sheet of gold was able to
be performed because gold is a soft metal that can be beaten into very thin sheets, just a few atoms thick, which alpha
particles can pass through. The alpha particles were emitted by a radioactive material that had been discovered just a few
years earlier. Find out more about this experiment. What was the source of the alpha particles? Can alpha particles pass
through any metal? Can any metal stop them? Did Rutherford suffer any long-term effects from his exposure to
radioactive materials?
ASSESSMENT RUBRIC
This is a self-assessed task. Use this rubric to grade your work and to also understand what is
required.
With an editing or formatting tool, select the grading that applies to your work for this task. Record
your grade below and any relevant comments you wish to make. I will also make a comment on
your submitted work.
Criteria
4
3
2
1
Understanding of
topic (elements)
A thorough and
detailed
understanding of the
topic has been
shown.
A good understanding
of the topic has been
shown. Some revision
may be required.
A reasonable
understanding of the
topic has been
shown. Revision is
required.
There is a lack of
understanding shown
about this topic.
More revision is
required.
Organisation of task
document
Headings
and subheadings
visually organize the
material. Pages are
broken at logical
places. Document
flows very well.
Headings
and subheadings
visually organize the
material. Pages are
broken at illogical
places. Document
flows well.
Some headings
and subheadings are
used to visually
organize the
material. Pages are
broken at logical
places. Document
does not always flow
well.
Headings
and subheadings are
not used to visually
organize the
material. Pages are
broken at logical
places. Document
does not flow well.
Completeness
All questions have
been attempted.
Answers have been
given in full
sentences. Extra
information is
included to support
answers.
All questions have
been attempted.
Answers have been
given in full sentences
at most times.
Some questions have
been attempted.
Answers have not
been given in full
sentences.
Many questions are
incomplete. Answers
have not been given
in full sentences.
Class time was always
used well and focus
on the task was well
maintained. There
were no problems
with having a laptop
or files organised.
Class time was usually
used well and focus
was usually
maintained. There
were few issues with
having a laptop or
files organised.
Use of time
STUDENT SELF-ASSESSMENT GRADE
STUDENT COMMENT:
TEACHER COMMENT:
More effort is
required in future.
/16
Class time was not
always used well
and/or focus was
intermittent. Greater
effort is required.
There were problems
with having a laptop
or files organised.
Greater effort is
required in future.
Class time was not
used well and focus
was not maintained
for this task.
Improvement
needed. There were
frequent problems
with having a laptop
or files organised.