Atomic Structure AS Level Chapters 2 and 3

Carbon and silicon have the same outer electronic structure. Why is a Si–Si bond weaker than a C–C bond?

• Silicon atoms have a larger atomic radius than carbon atoms.

• Silicon has a greater nuclear charge than carbon.

• Silicon has a smaller first ionisation energy than carbon.

• Silicon is more metallic than carbon.

Compound X is made from two elements. One element has the second highest value of first ionisation energy in its group and the other element has the third highest value of first ionisation energy in its group. Which compounds could be compound X?

1 calcium chloride

2 magnesium bromide

3 potassium sulfide

• 1,2,3 correct

• 1 and 2 correct

• 2 and 3 correct

• 1 correct

Why is the first ionisation energy of aluminium less than that of magnesium?

1 The outer electron in the aluminium atom is more shielded from the nuclear charge.

2 The outer electron in the aluminium atom is in a higher energy orbital.

3 The outer electron in the aluminium atom is further from the nucleus.

• 1,2,3 correct

• 1,2, correct

• 2,3 correct

• 1 correct

The first ionisation energies of twenty successive elements in the Periodic Table are represented in the graph. The letters given are not the normal symbols for these elements.

• 1,2,3 correct

• 1,2 correct

• 2,3 correct

• 1 correct

The ⁶⁸Ge isotope is medically useful because it undergoes a natural radioactive process to give an isotope of a different element, ⁶⁸X, which can be used to detect tumours. This transformation of ⁶⁸Ge occurs when an electron enters the nucleus and changes a proton into a neutron. Which statement about the composition of an atom of ⁶⁸X is correct?

• It has 4 electrons in its outer p orbitals.

• It has 13 electrons in its outer shell.

• It has 37 neutrons.

• Its proton number is 32.

What is the electronic configuration of an isolated Ni²⁺ ion?

• 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s²

• 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁸ 4s²

• 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s²

• 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁸

The graph shows the variation of the first ionisation energy with proton number for some elements. The letters used are not the usual symbols for the elements.

Which statement about the elements is correct?

• P and X are in the same period in the Periodic Table.

• The general increase from Q to X is due to increasing atomic radius.

• The small decrease from R to S is due to decreased shielding.

• The small decrease from U to V is due to repulsion between paired electrons.

Sodium azide, NaN₃ is an explosive used to inflate airbags in cars when they crash. It consists of positive sodium ions and negative azide ions. What are the numbers of electrons in the sodium ion and the azide ion?

• A

• B

• C

• D

The diagram shows the melting points of eight elements with consecutive atomic numbers. Which element could be sodium?

• A

• B

• C

• D

Which ion has the same electronic configuration as Cl^– ?

• F^–

• P⁺

• Sc³⁺

• Si⁴⁺