The Periodic Table

Question 1

What are the qualities of metallic elements?

Answer 1

In general metallic elements tend to have large atomic radii, low ionisation energies, less exothermic affinity values and low electronegativity.

Question 2

How does atomic radius vary across a period and down a group?

Answer 2

Atomic radius increases down a group as the number of electron shells increases.
Atomic radius decreases across a period as the positivity of the nucleus increases and so the electrons are pulled in tighter.

Question 3

How does ionic radius vary across a period and down a group?

Answer 3

In general the ionic radii of positive ions are smaller than the atomic radii of their atoms. and negative ions have a larger radii than their atoms.

Positive ions

• Increase down a group
• Decrease across a period

BIGGER
Negative ions
- Increase down group
- Decrease across a period

Question 4

What is ionisation energy?

Answer 4

The full definition of first ionisation energy is the energy required to remove one electron from each atom in one mole of gaseous atoms under standard conditions.

Question 5

How does ionisation vary across a period and down a group?

Answer 5

• Increases across a period (except for Al and S) which we know do not fit the trend, due to 2 different p orbitals being filled.
• Decreases down a group

Question 6

What is electron affinity?

Answer 6

The first electron affinity is the change in energy when one electron is added to each atom in one mole of gaseous atoms under standard conditions.

Question 7

How does electron affinity vary across a period and down a group?

Answer 7

Group 1
- Increases down a group

Group 7
- Decreases down a group

Becomes more exothermic as you do across the period.

Question 8

What is electronegativity?

Answer 8

Electronegativity is a measure of the attraction of an atom in a molecule for the electron pair in the covalent bond of which it is a part.

Question 9

How does electronegativity vary across a period and down a group?

Answer 9

Electronegativity decreases down a group

Increases across a period

Question 10

Why do elements in the same groups react the same way?

Answer 10

The reactions of an element are determined by the number of electrons in the outer shell (highest main energy level) of their atoms. Because elements in the same group in the periodic able have the same number of electrons in their outer shell, they react basically the same way.

Question 11

What does melting point do down group 1?

Answer 11

Melting point decreases down group 1 as the distance increases between the delocalised electrons and the nucleuses.

Question 12

How do group 1 react with oxygen?

Answer 12

4Na + O2 = 4Na2O

Form metal oxides

Question 13

How do group 1 react with water?

Answer 13

2Na + H2O = Na2OH + H2

THEY FORM HYDROXIDES

Question 14

What does the melting point in group 7 do?

Answer 14

The melting point increases as you go down the group? BECAUSE THE LONDON FORCES INCREASE.

Question 15

How does sodium oxide react with water?

Answer 15

Na2O + H2O = 2Na2OH

DOES NOT PRODUCE HYDROGEN THAT IS ONLY WHEN IT REACTS AS JUST SODIUM AND NOT SODIUM OXIDE. IT IS A HYDROGEN ACCEPTOR SO IS BASIC.

Question 16

How does magnesium oxide react with water?

Answer 16

MgO + H2O = Mg(OH)2

Question 17

What are the amphoteric oxides?

Answer 17

Just aluminium oxide

Question 18

How does aluminium oxide react with water?

Answer 18

IT IS AMPHOTERIC SO REACTS WITH BOTH!

Al2O3 + 3H+ = Al3+ + H2O (reaction with acids)
Al2O3 + 2OH- + 3H2O = Al(OH)-

Question 19

How does phosphorus oxide react with water?

Answer 19

P4O6 + 6H2O = 4H3PO4

Question 20

How does sulphur oxide react with water?

Answer 20

SO3 + H2O = H2SO4

They form an acidic substance, that can donate hydrogens!

Question 21

How does nitrogen oxide react with water?

Answer 21

These form acidic substances.
2NO2 + H2O = HNO2 + HNO3
ACID RAIN

Question 22

What is the definition of a transition metal?

Answer 22

A transition metal is an element that forms at least one stable ion with a partially filled d subshell.
Therefore zinc is not a transition metal because it has d10 and therefore a full d orbital.

Question 23

Which is added first and removed first, 3d or 4s?

Answer 23

4s is added first but also removed first to form an ion.

Question 24

What about the oxides of transition metals?

Answer 24

All transition metals show oxidation number +2, in most cases this is because they all have the 4s orbital which can be removed, therefore generating 2+.

Question 25

Why can transition metals have more than one oxidation number?

Answer 25

The 4s and the 3d sub-shells are very close in energy and there are no big jumps in the successive ionisation energies when the 4s and 3d orbitals are removed.

Question 26

What are the two forms of magnetism?

Answer 26

Paramagnetism and diamagnetism:

Paramagnetism - is caused by unpaired electrons, these substances are attracted by a magnetic field.

Diamagnetism - is caused by paired electrons these substances are repelled slightly by a magnetic field.

All substances have some paired electrons and so all exhibit diamagnetism. However the diamagnetic effect is much smaller than the paramagnetic effect and so if there are any unpaired electrons present, the paramagnetic effect will dominate and the substance will be paramagnetic and attracted by a magnetic field.

Question 27

What is a paramagnetic substance?

Answer 27

Paramagnetism - is caused by unpaired electrons, these substances are attracted by a magnetic field.

All substances have some paired electrons and so all exhibit diamagnetism. However the diamagnetic effect is much smaller than the paramagnetic effect and so if there are any unpaired electrons present, the paramagnetic effect will dominate and the substance will be paramagnetic and attracted by a magnetic field.

Question 28

What is a diamagnetic substance?

Answer 28

Diamagnetism - is caused by paired electrons these substances are repelled slightly by a magnetic field.

Question 29

What is a complex ion?

Answer 29

A complex ion consists of a central metal ion surrounded by ligands.

Question 30

What are ligands?

Answer 30

Ligands are negative ions or neutral molecules that have a lone pair of electrons. They use the lone pairs to bond to a metal ion to form a complex ion. Coordinate covalent bonds (dative bonds) are formed between the ligand and the transition metal ion.

Question 31

What shape will a complex ion be that has 6 ligands?

Answer 31

Octahedral

Question 32

What shape will a complex ion be that has 4 ligands?

Answer 32

tetrahedral or square planer

Question 33

Explain transition metal’s use in industry?

Answer 33

Transition metals can be used as catalysts. For example iron is used in the haber process.
Their ability to act as a catalyst relies on transition metal atoms or ions having varying oxidation numbers and also being able to coordinate to other molecules/ions to form complex ions.

Question 34

Why do transition metals form coloured complexes?

Answer 34

In a gaseous transition metal ion, all the 3d orbitals have the same energy, that is they are degenerate. However when the ion is surrounded by ligands in a complex ion these d orbitals are split into groups. In an octahedral complex ion there are 2 orbitals in the upper group and three orbitals in the lower group.
The splitting is caused by the repulsion between the electrons in the metal ion d orbitals and the lone pairs on the ligands.
Two of the metal d ion orbitals point directly at the ligands and so are raised in energy, whereas the other three d orbitals point between the ligands and are lowered in energy relative to the other two d orbitals.
When light passes through, some light energy is absorbed and raises an electrons from the lower orbitals to the higher ones. This wavelength of light is absorbed and therefore does not pass out the other side and the light that does appears the opposite colour on the wheel. It appears a complementary colour.
This is why transition metals have to have a partially filled d orbital so an electron can be raised.

Question 35

What are factors that effect the colour of transition metals?

Answer 35

• Identity of the metal
  for example, two metals that have the same number of electrons and therefore are isoelectric, so Fe3+ and Mn2+, Fe has a greater nuclear charge for the same number of electrons, therefore the electrons will be pulled in tighter and therefore be repelled and split more, absorbing a different colour to Mn.
• Oxidation number
  Because the electron configurations are different and the nuclear charge is different and so splitting is different.
• Nature of the ligand
  I- < Br- < Cl- < F- < OH- < H2O < NH3 < CO=CN-

Question 36

What is the order of ligands in how much they cause the orbitals to split>

Answer 36

I- < Br- < Cl- < F- < OH- < H2O < NH3 < CO=CN-