Metallic bonding Flashcards
What is metallic bonding?
The electrostatic forces of attraction between metal cations and delocalised electrons
A metallic structure description
Metal atoms release outer shell electrons to form cations
And these electrons are delocalised in a sea
And hold the structure together due to electrostatic attraction between electron and cation
Metal properties
High melting temperatures
Good electric conductivity
Good thermal conductivity
Malleability
Ductility
Insoluble
How to melt a metal?
By overcoming forces of electrostatic attraction between delocalised electrons and cations so the cations are free to move around the structure
So in the form of a liquid
Why are the valence electrons that were released said to be delocalised?
Because they are free to move throughout the structure and NOT localised (so delocalised) to one metal cation
Melting point of a metal
Very high
Why is the melting point of a metal high?
Because metals are usually in a giant lattice structure so there are a lot of forces of electrostatic attraction to be overcome between delocalised electrons and metal cations
Melting point trend in the periodic table in terms of electrons?
Increases across the period (Group 1 to 3)
Because there are more delocalised electrons per metal cation since the number of valence electrons increases
D block metals
Melting point trend in the periodic table in terms of size of cations?
Smaller cations (due to decrease in atomic radii across the periodamd up the group) means the delocalised electrons are closer to the nucleus so increased forces of electrostatic attraction
Thus require more energy to overcome forces and melt
How can metals conduct heat?
Because they transfer kinetic energy:
Cations are close together so pass Ek to each other
Delocalised electrons are moving and transfer Ek throughout lattice
Transferred to thermal energy
Malleability
The ability for metals to be hammered and pressed into different shapes
Ductility
The ability for metals to be stretched into a thin wire
Why are metals malleable and ductile?
Because when a stress is applied the layers of cations Slide over each other and electrons move with them since they are free moving
So prevents cation layers repelling each other = malleable
