Download T212 Atomic Structure Answers

Chemistry 11 (HL)
Unit 1 Review – IB Topics 2 and 12
Atomic Structure Past Paper Questions
CORRECTED ANSWERS – Please do not print.
PAPER 1
ANSWERS:
1.
B
6.
A
11.
D
2.
7.
12.
D
D
C
3.
8.
13.
B
C
B
4.
9.
14.
B
A
D
5.
10.
15.
D
C
D
16.
D
PAPER 2
17.
18.
19.
a)
IV (ultraviolet) < I (yellow) < II (red) < III (infrared)
b)
A continuous spectrum has all colours (or wavelengths) of radiation whereas a
line spectrum has only some specific / discrete colours (or wavelengths) which
appear is sharp lines.
c)
UV-B radiation has shorter wavelength than UV-A.
This means that UV-B radiation has more energy than UV-A.
UV-B will be more damaging to (skin) cells.
a)
Isotopes are atoms with the same atomic number but different mass numbers.
… or …
Isotopes are atoms with the same number of protons but different numbers of
neutrons.
b)
#p = 23, #e = 23, #n=27
c)
The more abundant isotope is 51V.
There are only two isotopes, with masses of 50 and 51. The average atomic mass is
50.94, which is much closer to 51. There must be more 51V in the sample than 50V.
d)
carbon-12
a)
i) ionization  acceleration  deflection
ii) ionization = sample is bombarded with high-energy/high-speed electrons
acceleration = + ions speed up when they move through an electric field (or past
oppositely charged plates)
deflection = a magnetic field bends the path of the ions (depending on the
mass/charge ratio of the ion)
b)
i) the weighted mean of the masses of all the (naturally occurring) isotopes of an
element, relative to the mass of an atom of carbon-12
ii) Ar = (70)(0.2260) + (72)(0.2545) + (74)(0.3673) + (76)(0.1522)
= 72.89
20.
i)
ii)
the number of protons (in the nucleus) of an atom
the number of protons and neutrons (in the nucleus) of an atom
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Chemistry 11 (HL)
21.
22.
Unit 1 Review – IB Topics 2 and 12
a)
see 18(a)
b)
Ar = (36)(0.00337) + (38)(0.000630) + (40)(0.996)
= 39.99
c)
#e = 23; #p = 26; #n = 30
a) See 17b.
b)
high energy
low energy
c) Each line is a discrete amount of energy. When electrons fall from one energy level to
another, only certain amounts of energy is released, as shown by each line. Thus
electrons can only be found in discrete energy levels.
23.
a)
b)
c)
24.
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2
i)
4p
ii)
Ge+(g)  Ge2+ (g) + 1 e– (g)
The 5th electron removed is from the 3rd energy level and is closer to the
nucleus, whereas the 4th electron removed is from the 4th energy level.
The attraction by the nucleus for the electrons is greater when the electrons
are closer to the nucleus.
The diagram below (not to scale) represents some of the electron energy levels in
the hydrogen atom.
________________________________ n = ∞
____________________________________________________________
n=6
________________________________ n = 5
________________________________ n = 4
________________________________ n = 3
A
B
________________________________ n = 2
________________________________ n = l
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Chemistry 11 (HL)
25.
26.
Si
P3–
i)
ii)
Unit 1 Review – IB Topics 2 and 12
2, 8, 4
2, 8, 8
1s2 2s2 2p6 3s2 3p6
K+ / Ca2+ and S2– / Cl–
ALSO REMEMBER TO LOOK AT THE ASSESSMENT STATEMENTS FOR THIS UNIT.
YOU COULD BE ASKED ANY QUESTION RELATED TO THOSE STATEMENTS.
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