Periodicity Flashcards

1
Q

What is melting ?

A

It involves breaking the lattice structure of a solid.

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2
Q

Define disproportionation.

A

It is the simultaneous reduction and oxidation of the same species.

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3
Q

Define amphoteric.

A

Having both basic and acidic properties.

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4
Q

Define electronegativity.

A

The measure of an atom’s ability to attract bonding electrons towards itself in a covalent bond.

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5
Q

How does the size of the electron cloud affect the covalent character of a compound ?

A

The bigger the electron cloud, the more polarisable the anion will be and thus the greater will be the covalent character.

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6
Q

Why do elements diagonal to each other have similar properties despite different valencies ?

A

They have similar electropositivity/electronegativity and similar charge density.

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7
Q

What affects the enthalpy change of lattice formation ?

A

The charge of and size of ions. As ionic radius decreases and ionic charge increases, the ionic compounds get more stable.

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8
Q

Define transition element.

A

An element that forms at least one compound with an incomplete d sub-shell.

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9
Q

What are the physical properties of transition elements ?

A
  • First row is only metals.
  • Little change in atomic/ionic radius and first IE.
  • Successive IE shows a steady increase instead of sudden jump because 3d and 4s orbitals have similar energies.
  • Hard and dense (small size + closely packed).
  • High m.p (strong metallic bonding).
  • good conductors (mobile electrons).
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10
Q

Why do transition elements have similar physical properties ?

A
  • Similar physical properties due to little difference in ENC –> each electron enters the penultimate 3d shell but the additional proton is partly shielded from the 4s electrons due to the additional 3d electron.
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11
Q

Define complex ion.

A

When a central metal atom/ion is bonded to surrounding anions or molecules (ligands) by dative bonds.

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12
Q

Define ligands.

A

Molecules/anions with a least one lone pair of electrons which can be used to form dative bonds with a transition metal atom/ion.

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13
Q

Define coordination number.

A

The number of dative bonds formed by the transition metal atom/ion with the ligand in the complex.

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14
Q

Coordination number (C no) and shape of complex ion.

A

C no : 2 Shape : linear
C no : 4 Shape : tetrahedral
C no : 6 Shape : octahedral

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15
Q

Define d-d splitting.

A

In the presence of ligands, the set of degenerate 3d orbitals of transition metal is split into 2 groups with slightly different energy.

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16
Q

Define d-d transition.

A

When 3d electrons from the lower energy group are promoted to the higher energy group, a photon of light from the visible region in the EMS is absorbed.

17
Q

Colour of Cr 2+

A

Blue

18
Q

Colour of Cr 3+

A

Green

19
Q

Colour of Cr2O4 (Dichromate VI)

A

Orange

20
Q

Colour of Mn 2+ (aq)

A

Pale pink

21
Q

Colour of MnO2 (s)

A

Black

22
Q

Colour of MnO4 - (aq) (Manganate VII)

A

Purple

23
Q

Colour of Fe 2+

A

Green

24
Q

Colour of Fe 3+

A

Yellow

25
Q

Colour of Fe(OH)2 (s)

A

Green ppt

26
Q

Colour of Fe(OH)3 (s)

A

Red brow ppt

27
Q

Colour of Cu2O (s)

A

Black ppt

28
Q

Colour of Cu 2+

A

Blue

29
Q

Colour of Cu(OH)2 (s)

A

Light blue ppt

30
Q

Colour of [CuCl4]^2- (aq)

A

Yellow

31
Q

Colour of [Cu(H2O)2(NH3)4]2+ (aq) or [Cu(NH3)4]2+

A

Dark blue

32
Q

What is Diamagnetism

A

Occurs when elements has no unpaired electrons, therefore are weakly repelled in a magnetic field.

33
Q

What is paramagnetism

A

Occurs when an element has one or more unpaired electron. They are attracted by an external magnetic field. Paramagnetism increases with an increase in the number of unpaired electrons.

34
Q

What is crystal field theory

A

This theory states that the properties of complex ions are caused by the splitting of the d orbitals into 2 sets of different energies.