L4C Chemistry to date

On this mass spectrum, which isotopes are present in the peak at m/z = 72?

• Chlorine-35

• Chorine-37

• Chlorine-36

• None of the above

Which of these species is NOT detected when chlorine molecules are ionised in a mass spectrometer?

Answer explanation

Only species with a charge are deflected to the detector in MS.

A diatomic element has two isotopes in equal abundance. How many peaks would there be in its mass spectrum?

Answer explanation

One for each monoatom, and three for the possible combinations of X2

A diatomic element has three isotopes in ratios 1:3:4 abundance. What would the ratio be of the peaks made by diatomic ions?

• 1:3:4

• 1:9:16

• 1:3:4:9:12:16

• 1:6:8:9:16:24

What is the electron configuration of copper?

From which orbital(s) are the first and second electrons removed when you ionise scandium twice?

• 4s, then 3d

• 3d, then 4s

• 3d only

• 4s only

Answer explanation

When ionising transition metals, electrons are always taken from the 4s first

Which of these has the highest first ionisation energy?

• Lithium

• Chlorine

• Nitrogen

• Oxygen

Answer explanation

Oxygen has more protons, yes, but the outermost electron is in the same p orbital as the previous, therefore experiences electron-electron repulsion.

On the graph shown, what is represented by the first jump.

• The outer electron being removed from a p orbital rather than an s orbital

• Electrons being removed from a shell that is nearer to the nucleus

• Electrons being removed from atoms with a smaller atomic radius.

• An increase in the number of protons in the nucleus meaning the electrons experience greater attraction.

Which of these are true about a 2s orbital compared to a 2p orbital

• Its electron density penetrates closer to the nucleus

• Its electrons shield the nucleus better than 2p's

• It is higher in energy than 2p.

• It can combine with other orbitals to form sigma bonds, but 2p orbitals cannot.

Which of these ionic compounds has the most covalent character?

• NaCl