OCR A Level Chemistry

Topic Questions

3.1 Periodicity

11 mark

What determines the order of elements in the Periodic Table?

  • First ionisation energy

  • Number of electrons in the outer shell

  • Number of protons in the nucleus

  • Relative atomic mass

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21 mark

Which element has the highest melting point?

  • Silicon

  • Phosphorus

  • Sulfur

  • Chlorine

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31 mark

Electron configurations for atoms of different elements are shown below. 

Which electron configuration represents the element with the largest first ionisation energy?

  • 1s22s2

  • 1s22s22p4

  • 1s22s22p6

  • 1s22s22p63s2

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41 mark

Sodium sulfide, Na2S, is a reactive yellow solid, produced when sodium and sulfur react together.

Which of the following statements is correct?

A

The ions have the same ionic radii

B

The atoms have the same atomic radii

C

Sodium < sulfur

D

Sodium > sulfur

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51 mark

The trends in three physical properties of the elements of Period 3 are shown in the graphs below.

periodicity-trends-period-3

 

Which physical property is not illustrated?

  • First ionisation energy 

  • Atomic radius

  • Melting point

  • Electrical conductivity 

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61 mark

What is the correct classification for the element zirconium, Zr?

  • s block

  • d block

  • f block

  • p block

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71 mark

What is the correct equation for the second ionisation energy of rubidium, Rb?

  • Rb+ (g) → Rb2+ (g) + e-

  • Rb (g) → Rb+ (g) + e-

  • Rb2+ (g) → Rb3+ (g) + e-

  • Rb2+ (g) + e- → Rb+ (g)

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81 mark

Why is the first ionisation energy of magnesium lower than the second ionisation energy?

  • Less shielding

  • Ionic radius increases

  • Nuclear charge increases

  • Greater attraction between positive nucleus and outer electron

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91 mark

The trend in melting points of some Period 3 elements can be represented as:

S8  > P4 > Cl2

What intermolecular force explains this trend in melting point?

  • Permanent dipole- dipole

  • Covalent bonding

  • Hydrogen bonding 

  • Induced dipole-dipole interactions

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11 mark

Successive ionisation energies of four elements in Period 3 are shown below.

Which letter could represent magnesium?

  1st (kJ mol-1) 2nd (kJ mol-1) 3rd (kJ mol-1) 4th (kJ mol-1) 5th (kJ mol-1)
A 1251 2298 3822 5159 6542
B 738 1451 7733 10543 13630
C 496 4563 6913 9544 13352
D 578 1817 2745 11577 14842

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21 mark

Which statement about trends in first ionisation energies is correct?

  • The first ionisation energy generally increases across a period due to increased nuclear charge and shielding.

  • First ionisation energy drops between magnesium and aluminium because the outer electron is in the 3p subshell which is higher in energy than the 3s orbital. 

  • First ionisation energy drops between nitrogen and oxygen because the spin-pair repulsion of the 2p electron means that this electron is higher energy.

  • First ionisation energy down a group increases due to increased nuclear charge. 

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31 mark

The successive ionisation energies of elements X and Y are shown below.

Element X

IE

1st

2nd

3rd

4th

5th

6th

7th

8th

IE (kJ mol-1)

590

1145

4912

6491

8153

10496

12270

14206

 

Element Y

IE

1st

2nd

3rd

4th

5th

6th

7th

8th

IE (kJ mol-1)

1012

1907

2914

4964

6274

21267

25431

29872

 

X and Y form ions with the same electron configuration as argon.

What are the identities of elements X and Y respectively?

  • Calcium and phosphorus 

  • Sodium and oxygen

  • Magnesium and nitrogen

  • Phosphorus and potassium 

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41 mark

In which row is the first ionisation energy of atom Y greater than that of atom X?

 

Element X

Element Y

A

1s22s22p63s2

1s22s22p63s23p1

B

1s22s22p63s23p3

1s22s22p63s23p4

C

1s22s22p63s23p5

1s22s22p63s23p6

D

1s22s22p63s23p6

1s22s22p63s23p64s1

 

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51 mark

Which row is correct?

Property

Increasing order

Atomic radius

Nitrogen, oxygen, fluorine

First ionisation energy

Lithium, beryllium, boron

Electronegativity

Nitrogen, carbon, boron

Melting Point

Neon, fluorine, oxygen

 

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1
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1 mark

In the Periodic Table, element X is in Group 3 and element Y is in Group 16 (6).
What is the likely formula of an ionic compound of X and Y?

  • X3Y6

  • X3Y2

  • X2Y3

  • X6Y3

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21 mark

What determines the order of elements in the Periodic Table?

  • First ionisation energy

  • Number of electrons in the outer shell

  • Number of protons in the nucleus

  • Relative atomic mass

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31 mark

Which element has the highest melting point?

  • Silicon

  • Phosphorus

  • Sulfur

  • Chlorine

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41 mark

Which trend in the periodic table is correct?

  • Melting point decreases from lithium to carbon

  • Boiling point decreases from fluorine to iodine

  • First ionisation energy decreases from lithium to caesium

  • First ionisation energy increases from nitrogen to oxygen

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51 mark

Which statement best explains why phosphorus has a larger first ionisation energy than sulfur?

  • P atoms have less repulsion between p-orbital electrons than S atoms

  • P atoms have a smaller nuclear charge than S atoms

  • P atoms lose an electron from the 3s subshell, while S atoms lose an electron from the 3p subshell

  • P atoms have an odd number of electrons, while S atoms have an even number

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6
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1 mark

The first five successive ionisation energies of an element Z are shown below.

1st 2nd 3rd 4th 5th
495 4563 6914 9543 13351

What is the formula of a hydroxide of Z?

  • ZOH

  • Z(OH)2

  • Z(OH)3

  • Z(OH)4

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71 mark

Which p-block element contains atoms with one unpaired electron?

  • B

  • C

  • N

  • O

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81 mark

Which statement below shows the correct information about diamond and graphite?

  • Diamond and graphite both conduct electricity due to delocalised electrons in their structure

  • The bond angles in the two structures are not the same

  • Diamond is macromolecular and graphite is simple molecular

  • All the valence electrons are covalently bonded in both graphite and diamond

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91 mark

Consecutive elements X, Y and Z, are in the third period of the periodic table. Element Y has the highest first ionisation energy and the lowest melting point of these three elements.

What could be the identities of X, Y and Z?

  • Silicon, phosphorus, sulfur

  • Sodium, magnesium, aluminium

  • Aluminium, silicon, phosphorus

  • Magnesium, aluminium, silicon

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101 mark

Which of the following metals would have the highest melting point?

  • Na

  • Mg

  • K

  • Al

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111 mark

Which statement best explains why nitrogen has a larger first ionisation energy than oxygen?

  • N atoms have less repulsion between p-orbital electrons than O atoms.

  • N atoms have a smaller nuclear charge than O atoms.

  • N atoms lose an electron from the 2s subshell, while O atoms lose an electron from the 2p subshell.

  • N atoms have an odd number of electrons, while O atoms have an even number.

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