Structure 2.4
No description yet. This curated deck is ready for daily study.
Card preview (20)
Simple bonding triangle
Shows the three extreme types of bonding based on difference in electronegativity value plotted against the average electronegativity for binary compounds
Covalent bonds
The electrostatic attractions between the nuclei of two atoms and their valence electrons; sharing of electrons to form electron pairs between non-metal atoms.
Ionic Bonds
The electrostatic attractions between oppositely charged ions.
Metallic Bonds
The electrostatic attractions between cations and the sea of delocalised valence electrons
When does a solid melt
When the attractive forces between its particles are overcome leaving the particles free to move.
Melting point trends
Similar to bp trends however thy are also effected by the way in which the particles pack in the solid state
Elasticity
The ability of a material to resist a distorting influence and return to its original size and shape when the distorting force is removed.
Brittle
Fracture under stress rather than undergo deformation because the bonds cannot be reformed once they are broken.
What makes metals malleable/ductile
The layers of cations can slide over each other without breaking when a force is applied
Why are ionic solids brittle
The lattice breaks without being deformed when sufficient force is applied
Alloy
A mixture of more than one metal
Why are alloys harder
The impurities added disturb the lattice and make it harder for the layers to slide over each other
Why are the properties of alloys different to that of the metal they are derived from?
The added metal has a different atomic radius which distorts the crystalline structure making the bonding less directional.
Polymers
Chains of monomers
Monomers
Single repeating units
What are the two ways monomers join to form polymers
Addition and condensation reactions
Thermoplastics
Soften when heated and harden when cooled. Can be remoulded by heating again.
Thermosetting polymers
Change irreversibly when heated and cannot be remoulded after cooling.
Elastomers
Flexible and can be reformed under a force but will return to their original shape once released eg rubber
What sort of monomers are used to form addition polymers
Ones with a double bond which can break to create new bonding positions for the attachment of neighbouring monomers