Download SCI 1.5 (AS90189) – Homework Set 1: ATOMIC STRUCTURE

SCI 1.5 (AS90189) – Homework Set 1: ATOMIC STRUCTURE - Solutions
QUESTION ONE (2009, Question 1)
Question
ONE
(a)
(b)
Achievement
Excellence
ONE Correct Statement. (a)
12
C: 6 protons, 6 neutrons
OR
13
C: 6 protons, 7 neutrons
OR
Electron configuration of 2.4 for
both 12C AND 13 C
OR
An atom is neutral when it has
equal numbers of protons and
electrons.
OR
Relevant labelled diagram.
Atomic structure and electron
configuration given for BOTH
12
C and 13C PLUS an explanation
why they are neutral. (m)
12
C: 6 protons, 6 neutrons, electron
configuration of 2.4
13
C: 6 protons, 7 neutrons, electron
configuration of 2.4
AND
12
C and 13 C are neutral as they both
contain equal numbers of protons
and electrons.
ONE correct statement. (a)
Explains how particles contribute
to the overall mass. (m)
Mass is found by adding up protons
and neutrons.
OR
Electrons have negligible mass (and
are not included in mass
calculation).
OR
Protons and neutrons make up
(nearly) all the mass.
(c)
Merit
ONE correct statement. (a)
13
N: 7 protons, 6 neutrons
(or diagram).
OR
The mass of 13 N and 13 C are
(nearly) the same.
OR
12 and 13 refer to total mass of
element(s).
OR
Mass of 13 N is greater than 12C.
Explains that the overall mass of an
atom is made up of protons and
neutrons, as the mass of the
electrons is negligible.
ONE correct explanation. (m)
13
N will have the same atomic mass
as 13 C because the total number of
protons and neutrons is the same.
OR
13
N is heavier than 12C because it
has one extra proton / extra particle.
Discusses how the mass of N13 compares to the other
isotopes. (e)
13
N will have the same atomic
mass as 13 C because the total
number of protons and
neutrons is the same.
AND
13
N is heavier than 12C because
it has one extra proton.
QUESTION TWO (2008, Question 1a)
Question Evidence
ONE
(a)
(b)
Diagram showing 8 protons and 10
neutrons in nucleus, with 8 electrons
orbiting, 2 in first shell, six in second.
Atom is neutral as there are the same
number of positive particles / charges /
protons as negative particles / charges /
electrons.
Achievement
Merit
Correct number of
Correct diagram
protons, neutrons and AND
arrangement of
explanation.
electrons in diagram
(accept conventional
symbols (+ for
protons, – for
electrons), or p / n /
e)
OR description of
same number of
protons and electrons
/positive and negative
particles or charges
Excellence
QUESTION THREE (2007, Question 1a,b)
Q
Evidence
Achievement
1(a)
(i)
protons = 19
electrons = 19
neutrons = 20
All correct.
(a)
(ii)
protons and neutrons
Both correct.
(a)
(iii)
2,8,8,1
Correct.
(b)
Similarities
• All three have same
number of protons (3).
Differences
• Number of neutrons are
different between 6Li and
7
Li, 6Li has 3, 7Li has 4.
• Number of electrons are
different between the ion
and the atoms. Li+ has 2
electrons whereas 6Li and
7
Li have 3.
Either a similarity or
difference described or
complete description of
one species.
QUESTION FOUR (2006, Question 1a,b)
Question
Evidence
1(a)
proton +
electron
neutron
Achievement
Merit
Uses a similarity and a
difference to explain
atomic structure.
Merit
Excellence
Uses one similarity and
two differences,
including numbers, to
compare and contrast
atomic structure.
Excellence
(a) correct
T
T
1(b)(i)
Diagram showing 12 
and 11 + in nucleus;
11 electrons orbit nucleus
arranged 2, 8, 1.
Electrons correct, ie 2,8,1
configuration.
Achievement PLUS 11
protons and 12 neutrons in
nucleus.
1(b)(ii)
Sodium atom and sodium
ion both have 11 protons
in nucleus and both have
12 neutrons in the nucleus,
ie no differences in
nucleus.
Sodium atom has one
more electron than sodium
ion and has three shells
containing electrons.
PLUS
Sodium ion has a positive
charge of one, whereas
sodium atom is neutral.
Comparison between atom
and ion of TWO of the 4
criteria (number of
protons, neutrons and
electrons and charge), eg:
Atom loses electron to
form ion and they have the
same number of protons.
OR
The atom is neutral it loses
1 electron to become a
positive ion.
Comparison between atom
and ion of THREE of the
4 criteria (number of
protons, neutrons and
electrons and charge), eg:
Atom loses electron to
form ion and they have the
same number of protons
and neutrons.
OR
Atom has 11 protons, 12
neutrons, 11 electrons and
ion has 11 protons, 12
neutrons and 10 electrons.
Comparison between atom
and ion of FOUR of the 4
criteria (number of
protons, neutrons and
electrons and charge) with
specific details.
PLUS
The reason behind ion
formation based on shells /
electron configuration.