Chemistry - Bonding, Structure & Properties of Matter (Part 2) Flashcards
What are polymers and their structure?
A molecular substance that is a plastic. They are very large molecules with hundreds or thousands of atoms, joined by covalent bonds.
What are giant covalent substances?
Give some examples
Atoms joined by covalent bonds in a continous network
- Diamond
- Graphite
- Silicon
What is the structure of giant covalent substances?
All atoms are in a giant lattice - joined together by covalent bonds in a continous network.
What are the melting and boiling points of giant covalent substances and why are they this way?
They have very high melting points because they take a lot of energy to break (due to the many covalent bonds). E.g.: diamond is 3500 degrees
Do giant covalent substances conduct electricity?
Most do not because they do not have delocalised electrons. However, graphite does because they have delocalised electrons able to move throughout the substance.
What are metallic substances?
Metals - over 3/4 of elements are metals and therefore have a metallic structure
What is the structure of metallic substances like?
A giant lattice of atoms arranged in a regular pattern. The outer shell of electrons are delocalised which means they are free to move throughout the whole structure.
There is a strong attraction between the positive nucleus and the delocalised electrons - called metallic bonding
What are the melting and boiling points of metallic substances?
Metallic bonding is strong so they have high melting and boiling points - e.g.: Iron is 1538 degrees.
What are the melting and boiling points of metallic substances?
Metallic bonding is strong so they have high melting and boiling points - e.g.: Iron is 1538 degrees.
Do metallic substances conduct electricity?
Metals are good conductors of electricity as they have delocalised electrons.
Metals are malleable, what does they mean and why are they this way?
They can be bent or hammered into a different shape. Because layers of atoms can slide over each other maintaining the metallic bonding.
What is an alloy?
A mixture of metals with a small amount of other elements. Because pure metals are too soft, they can lose their shape easily. Making them into alloys will prevent this. E.g.: gold alloys are used for jewellery as pure gold would lose its shape.
