SUMMATIVE ASSESSMENT TASKS
Summative assessment for the unit “11.1.A Atom structure”
Learning objectives
11.1.1.4 be able to calculate relative atomic, molecular and formula
mass
11.1.2.2 recall a block diagram of the mass spectrometer
11.1.2.4 be able to interpret a simple mass spectrum to obtain relative
atomic mass and relative molecular mass
11.1.3.3 understand the rules for the filling of shells and sub-shells
11.1.3.7 understand the factors affecting ionisation energy: nuclear
charge, distance from the nucleus, shielding
Assessment criteria
Learners should be able to:
- calculate the relative atomic mass of an element given the
relative abundances of its isotopes;
- name the main parts of the mass-spectrometer
- interpret simple mass spectra of elements to calculate relative
atomic mass from isotopic abundance;
- write electron configurations of atoms and ions in terms of
shells and sub-shells (orbitals) s, p and d
- state the trends in ionisation energies across a period and
explain the factors influencing the ionisation energies
Level of thinking
skills
Knowledge and comprehension
Application
Higher order thinking skills
20 minutes
Duration
Task
1. Bromine occurs as two stable isotopes in the Earth’s crust, bromine-79 and bromine-81.
The relative abundances of these are 50.5% and 49.5% respectively. Use these data to
calculate the relative atomic mass of bromine.
2. The relative atomic mass of a sample of iron may be found by using a mass
spectrometer to determine the isotopic composition.
(i)The diagram below represents a low-resolution mass spectrometer in which four areas have
been identified. Name the process occurring in each of the areas labelled B, C and D
Area A Ionisation
Area B ....................................
Area C .....................................
Area D .......................................
3. The mass spectrum of a sample of krypton taken from a meteorite is shown below
Use this spectrum to calculate the relative atomic mass of this sample of krypton.
4. Complete the electronic configurations for the metals sodium and iron.
Electronic configuration of sodium
1s2..................................................................
Electronic configuration of iron
1 s2.......................................................................
Give the electronic configuration of the F– ion in terms of levels and sub-levels.
...........................................................................................................................
5. The diagram below shows the variation in first ionisation energy across Period 3.
State and explain the general trend in first ionisation energies for the Period 3 elements
aluminium to argon.
Assessment criteria
Calculate
the
relative
atomic mass of an element
given
the
relative
abundances of its isotopes;
Task
1
Descriptor
A learner
presents working in calculations
Interpret
simple
mass 3
spectra of elements to
calculate relative atomic
mass
from
isotopic
abundance;
Write
electron 4
configurations of atoms and
ions in terms of shells and
sub-shells (orbitals) s, p and
d
State the trends in ionisation 5
energies across a period and
explain
the
factors
influencing the ionisation
energies
Total marks
1
calculates the relative atomic mass of an
element given the relative abundances of its
isotopes
1
name the processes occurring in each of the
areas labeled B, C and D
3 (one
mark
for
each)
provides the algorithm for calculation
1
uses mass spectrum to calculate the relative
atomic mass of krypton
1
writes electron configurations of sodium
1
writes electron configurations of iron
1
writes electron configurations of F- ion
1
2
Name the main parts of the
mass-spectrometer
Mark
states the trends in ionisation energies across
1
a period
refers to the nuclear charge
1
refers to the shielding effect
1
13
Rubrics for providing information to parents on the result of Summative Assessment for
the unit “Atomic structure”
Learner’s name:________________________________________________________
Assessment
criteria
Calculate
the
relative
atomic
mass of an element
given the relative
abundances of its
isotopes;
Level of learning achievements
Low
Middle
High
Experiences challenges Makes some mistakes Presents working and
in presenting algorithm in presenting algorithm calculates the relative
of solution and makes of calculation of the atomic mass of an
mistakes in calculating relative atomic mass of element given the
the relative atomic an element given the relative abundances of
mass.
relative abundances of its isotopes;
its isotopes;
Experiences difficulties Makes some mistakes Name the main parts
in naming parts of mass in naming the main of mass spectrometer
Name the main
spectrometer
parts
of
mass- correctly.
parts of the massspectrometer.
spectrometer
Interpret
simple
mass spectra of
elements
and
calculate relative
atomic mass from
isotopic
abundance;
Experiences challenges
in interpreting simple
mass spectra and makes
mistakes in calculating
the relative atomic mass
Makes some mistakes
in interpreting simple
mass
spectra
of
elements to calculate
relative atomic mass
from
isotopic
abundance
Interprets simple mass
spectra of elements
and
correctly
calculates
relative
atomic mass from
isotopic abundance
Write
electron
configurations of
atoms and ions in
terms of shells and
sub-shells
(orbitals) s, p and d
Experiences difficulties
in writing electron
configurations of atoms
and ions in terms of
shells and sub-shells
(orbitals) s, p and d
Makes some mistakes
in writing electron
configurations of atoms
and ions in terms of
shells and sub-shells
(orbitals) s, p and d
Correctly completes
electron
configurations
of
atoms and ions in
terms of shells and
sub-shells (orbitals) s,
p and d
Experiences difficulties
State the trends in in explaining
the
ionisation energies factors influencing the
across a period and ionisation energy
explain the factors
influencing
the
ionisation energies
Makes some mistakes
in explaining
the
factors influencing the
ionisation energy
States the trends in
ionisation
energies
across a period and
explains the factors
influencing
the
ionisation energies