U2.3 Metallic Model Flashcards
Properties of metals?
- Sononous
- Malleable
- Good conductors of heat and electricity
- Hard
- High melting point
- Lustrous
Explain how metal is a good electrical conductor
There are delocalised electrons that are mobile or free to move
Explain how metal is a good thermal conductor
Delocalised electrons and closely packed ions enable efficient transfer of thermal energy
Explain how metal is malleable and ductile
Movement of delocalised electrons is non-directional and random through the cation lattice whilst the metallic bond still remains intact
Explain how metal has a high melting point
Lots of energy is required to overcome the strong electrostatic forces of attraction
Explain how metal is lustrous
Delocalised electrons in metal crystal structure reflect light
Explain how metal is hard
There are strong electrostatic forces of attraction between closely packed metal ions and delocalised electrons
Define what an Alloy is
A mixture of metals with other metals or non-metals
Outline the main property of alloys different to normal metals
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
Define metallic bonding
Electrostatic forces of attraction between the sea of delocalised electrons and cations in the same type of metal
Properties of steel?
- It is a common alloy
- It is harder and stronger than pure iron thus, can be used as a more suitable material for construction
Outline the relationship between the atomic radius decreasing or increasing across a period or down a group
Down a group:
- Atomic radius increases due to increasing number of electron shells
Across a period:
- Atomic radius decrease due to increasing nuclear charge
Factors affecting strength of the Electrostatic forces of attraction between delocalised electrons and cations within the metallic lattice
- 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)
What is the simple one sentence relation between the strength of the metallic bond, the radius and charge of the metal ion?
- The smaller the radius and greater the charge of the metal ion, the stronger the metallic bond
and v.v
Explain the trends in melting points of s and p block metals
- 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.
Define ‘Hardness’ in terms of metals
- The ability of a material to resist deformation
State the relationship between the hardness of a metal and the strength of the metallic bonds
- The stronger a metallic bond is, the greater the strength of the metallic bond
State the group number range (in the first row) of d block metals
- 5 to 11
What is the main difference in the transition metals found in period 4 (d block metals)
- 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
Explain the relationship between increased electron density and strength of metallic bond in d block metals
- 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
Explain the high melting point of transition elements (the use of delocalised d-orbitals)
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.
Explain the hardness of a transition element, Copper.
- 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
Explain the high electrical conductivity of transition elements (the use of delocalised d-orbitals)
- 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
State the properties of copper (a transition metal) that allow it to be used for electrical wiring
- high electrical conductivity
- malleable
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)
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
