atomic structure exam question Flashcards
In a time of flight mass spectrometer, molecule X is ionised using electrospray ionisation.
What is the equation for this ionisation?
A X(l) + e– → X+(g) + 2 e–
B X(g) + e– → X+(g) + 2 e–
C X(l) + H+ → XH+(g)
D X(g) + H+ → XH+(g)
D X(g) + H+ → XH+(g)
What is the electron configuration of V2+ in the ground state?
A 1s2 2s2 2p6 3s2 3p6 3d3
B 1s2 2s2 2p6 3s2 3p6 3d1 4s2
C 1s2 2s2 2p6 3s2 3p6 3d3 4s2
D 1s2 2s2 2p6 3s2 3p6 3d5 4s2
A 1s2 2s2 2p6 3s2 3p6 3d3
Which has the electron configuration of a noble gas?
A H+
B O–
C Se2–
D Zn2+
C Se2–
This question is about time of flight (TOF) mass spectrometry.
(a) Define the term relative atomic mass.
the average mass of an element
This question is about the isotopes of chromium.
(a) Give the meaning of the term relative atomic mass.
average/mean mass of 1 atom of an element
1/12 mass of one atom of 12Cr
The sample of chromium is analysed in a time of flight (TOF) mass spectrometer.
(d) Give two reasons why it is necessary to ionise the isotopes of chromium before they can be analysed in a TOF mass spectrometer.
- so they are attracted to the negativley charged plate
- so the ions can hit the detector and create a current
(c) A sample of germanium is analysed in a TOF mass spectrometer using electron impact ionisation.
Give an equation, including state symbols, for the process that occurs during the ionisation of a germanium atom.
Ge (g) + e- –> Ge+ (g) + 2e-
The first ionisation energies of the elements in Period 2 change as the atomic number increases.
Explain the pattern in the first ionisation energies of the elements from lithium to neon. [6 marks]
1st ionization energy increase
greater nuclear charge (more protons)
similar electron shielding
electrons in the same energy levle
stronger attractino between the nucleus and the outer electron
B lower thna BE
outer electron in 2p
2 electronis n 2p need to pair
pairing causes repulsion
Describe the process of electrospray ionisation.
Give an equation to represent the ionisation of P in this process.
P + H+ –> PH+
Which atom has the greatest first ionisation energy?
A H
B He
C Li
D Ne
He
State which of the elements magnesium and aluminium has the lower first ionisation energy.
Explain your answer.
Al
outer electron in 3p sublevel
higher energy further from the nucleus so easier to remove an outer electron
State how, if at all, the chemical properties of these isotopes differ.
Give a reason for your answer.
chemical properties dont differ
all have the same electronic configration or soame number of outer electrons
Element Q forms a sulfate with formula QSO4
Which of these could represent the electronic configuration of an atom of Q?
A [Ne]3s1
B [Ne]3s2
C [Ne]3s23p1
D [Ne]3s13p2
B
[Ne]3s2
Bromine exists as two isotopes 79Br and 81Br, which are found in almost equal abundance. Which of the statements is correct?
A The first ionisation energy of 79Br is less than the first ionisation energy of 81Br
B The atomic radius of 79Br is less than the atomic radius of 81Br
C The mass spectrum of C3H7Br has two molecular ion peaks at 122 and 124
D 79Br is more reactive than 81Br
C
The mass spectrum of C3H7Br has two molecular ion peaks at 122 and 124
Outline how the TOF mass spectrometer is able to separate these two
species to give two peaks.
- positive ions are accelerated
- lighter ions and more charged ions reach a higher speed
- constant kinetic energy
- … ion arrives at the detector first
