U2.3 Metallic Model

Question 1

Properties of metals?

Answer 1

• Sononous
• Malleable
• Good conductors of heat and electricity
• Hard
• High melting point
• Lustrous

Question 2

Explain how metal is a good electrical conductor

Answer 2

There are delocalised electrons that are mobile or free to move

Question 3

Explain how metal is a good thermal conductor

Answer 3

Delocalised electrons and closely packed ions enable efficient transfer of thermal energy

Question 4

Explain how metal is malleable and ductile

Answer 4

Movement of delocalised electrons is non-directional and random through the cation lattice whilst the metallic bond still remains intact

Question 5

Explain how metal has a high melting point

Answer 5

Lots of energy is required to overcome the strong electrostatic forces of attraction

Question 6

Explain how metal is lustrous

Answer 6

Delocalised electrons in metal crystal structure reflect light

Question 7

Explain how metal is hard

Answer 7

There are strong electrostatic forces of attraction between closely packed metal ions and delocalised electrons

Question 8

Define what an Alloy is

Answer 8

A mixture of metals with other metals or non-metals

Question 9

Outline the main property of alloys different to normal metals

Answer 9

Alloys are harder and stronger
- There are atoms of different sizes that disrupt the layers of metals
- Thus, a greater force is required for the layers to slide over one another

Question 10

Define metallic bonding

Answer 10

Electrostatic forces of attraction between the sea of delocalised electrons and cations in the same type of metal

Question 11

Properties of steel?

Answer 11

• It is a common alloy
• It is harder and stronger than pure iron thus, can be used as a more suitable material for construction

Question 12

Outline the relationship between the atomic radius decreasing or increasing across a period or down a group

Answer 12

Down a group:
- Atomic radius increases due to increasing number of electron shells

Across a period:
- Atomic radius decrease due to increasing nuclear charge

Question 13

Factors affecting strength of the Electrostatic forces of attraction between delocalised electrons and cations within the metallic lattice

Answer 13

• Radius of the metal ion; smaller the radius, stronger the metallic bond. This is due to the shorter distance bew. +ve nucleus of cation and outer valence delocalised electrons; Requires more energy to break.
• Ionic charge of the metal ion; greater the charge, stronger the metallic bond. This is due to the greater charge difference as a result of a greater number of valence delocalised electrons which increases the strength of the Electrostatic force of attraction between metal ions and delocalised electrons.

(same as factors affecting ionic bonding)

Question 14

What is the simple one sentence relation between the strength of the metallic bond, the radius and charge of the metal ion?

Answer 14

• The smaller the radius and greater the charge of the metal ion, the stronger the metallic bond

and v.v

Question 15

Explain the trends in melting points of s and p block metals

Answer 15

• Going down these groups of metals, melting point decreases. This is because of the decreased strength of the metallic bond as the radius of the metal ion increases down the group.
• Across the period for these groups of metals, the melting point increases due to the increased strength of the metallic bond as charge of metal ion increases.

Question 16

Define ‘Hardness’ in terms of metals

Answer 16

• The ability of a material to resist deformation

Question 17

State the relationship between the hardness of a metal and the strength of the metallic bonds

Answer 17

• The stronger a metallic bond is, the greater the strength of the metallic bond

Question 18

State the group number range (in the first row) of d block metals

Answer 18

• 5 to 11

Question 19

What is the main difference in the transition metals found in period 4 (d block metals)

Answer 19

• They have valence electrons occupying 4s and 3d orbitals
• This means that there are many possible ionic charges that these can form as they are loosely bound throughout the metallic lattice

Question 20

Explain the relationship between increased electron density and strength of metallic bond in d block metals

Answer 20

• As there are lots of valence electrons in both the s and d orbitals, there is increased electron density
• The increased electron density increases the strength of the metallic bond

Question 21

Explain the high melting point of transition elements (the use of delocalised d-orbitals)

Answer 21

High melting point:
- large number of delocalised electrons from 4s and 3d orbitals increases the attraction betw. delocalised electrons and cations in the lattice. Thus, resulting in increased strength of metallic bond which requires lots of energy to overcome.

Question 22

Explain the hardness of a transition element, Copper.

Answer 22

• Copper has both 4s and 3d electrons as delocalised valence electrons
• There is increased attraction between these electrons and the metal ions in the lattice
• This increases the strength of metallic bonds

Question 23

Explain the high electrical conductivity of transition elements (the use of delocalised d-orbitals)

Answer 23

• Electrostatic forces of attraction betw. metal ions in the lattice and delocalised electrons increases
• This is due to the increasing electron density in d orbitals
• As the delocalised electrons in the d orbitals are free to move, they are able to conduct electricity and carry a charge

Question 24

State the properties of copper (a transition metal) that allow it to be used for electrical wiring

Answer 24

• high electrical conductivity
• malleable

Question 25

Explain why the melting points of the group 1 metals decrease down the group whereas the melting point of group 7 ELEMENTS increase down the group (3)

Answer 25

Group 1:
- Down the group, the attraction between the nucleus and sea of delocalised e- gets weaker
- Ionic radius increases
- Electrostatic attraction between cations and delocalised e- decreases

Group 7:
- Down the group, intermolecular forces of attraction between outer valence e- and nucleus get stronger as # of electrons increases
- LDF between molecules gets stronger