Properties Of Materials Flashcards
Why can carbon form different compounds? What are allotropes?
Carbon has 4 outer shell electrons so it can from 4 covalent bonds. Allotropes are different forms of an element in the same state but with different atomic arrangements.
What are the allotropes of carbon and their properties?
Diamond- Each carbon has 4 strong covalent bonds which means it its hard and non-conductive. Transparent too.
Graphite- Each carbon has 3 covalent bonds so it can conduct. It is layered but each layer has weak intermolecular forces they can slide over each other: graphite is soft.
Graphene- Is one layer of graphite so conductive and strong
Fullerene- Structure of a tube or ball. Nanotube resembles graphene rolled into a tube. Buckyball resembles graphene rolled into a hollow ball. Acts as lubricant: small ball bearing.
What happens when a substance melts or boils?
What happens when a substance condenses or freezes?
-Melting: Some bonds break from solid to liquid
-Boiling: All bonds break from liquid to gas
-Condensing: Some bonds form from gas to liquid
-Freezing: Many bonds form from liquid to solid
What bonds are broken in particular instances?
Giant Metallic Lattice / Metallic bonds / Strong / Iron, Mercury
Giant Ionic Lattice / Ionic Bonds / Strong / Sodium Chloride
Giant Covalent Structure / Covalent Bonds / Strong / Diamond, Silicon Dioxide
Simple Molecule / Intermolecular Bonds / Weak / Oxygen, Water
Why are substances brittle or malleable?
Depends on how easily particles move in lattice structure.
Malleable: Metals are malleable because the layers of metal slide over each other and no bonds are broken because the delocalised electrons move.
Brittle: Giant covalent structures/Ionic compounds are brittle because its structure has many atoms in a giant lattice held together. If a large enough force is applied, lots of covalent bonds break at once and it shatters.
How big are nanoparticles?
What are there uses?
From 1nm to 100nm apart across consisting of a few hundred atoms.
Materials made of nanoparticles are nanoparticulate having different properties to the same substance in bulk because of the size difference. They are used for paints, cosmetics, catalysts and self cleaning items.
What are the possible risks of nanoparticles?
Nanoparticles are so small they can be breathed in, absorbed by the skin or pass into cells. Nanoparticles take a long time to break down and may release toxic substances into the environment. This is why they can be dangerous when used in sunscreens.
