P1 - Bonding, Structure, And Properties Of Matter Flashcards
Do metals form a positive or negative ion?
Positive - because they lose electrons (losing negativity so they become positive :D )
Do non-metals for positive or negative ions?
Negative - they gain electrons (gain negativity so become negative)
What is ionic bonding?
When a metal and non-metal react together, and the metal transfers electrons to the non-metal so that they both have full outer shells. They are then strongly attracted to one another by electrostatic forces.
How do you show ionic compounds as a diagram?
You use a dot and cross diagram. The dots representing the electrons on one element and the crosses representing the electrons on the other element.
What kind of structure do ionic compounds form?
They form giant ionic lattice structures.
What are the properties of ionic compounds?
- High melting and boiling points
- When solid they can’t conduct electricity because they are so tightly packed, but when a liquid they can carry electric current
- Dissolve easily in water
What is covalent bonding?
When two non-metals bond together by sharing their electrons so that each has a full outer shell. They are attracted by electrostatic forces.
How do you show covalent bonding in a diagram?
Using a dot and cross diagram and overlapping the outer shells. In the overlapped area will be the electrons that are shared between the two elements.
Define a simple molecular substance
Substances that are made up of molecules containing few atoms joined together by covalent bonds.
Examples: hydrogen, chlorine, oxygen, nitrogen, methane, water, hydrogen chloride
What are the properties of simple molecular substances?
- Very strong covalent bonds
- Forces between molecules are weak
- Low boiling and melting points
- Gases or liquids at room temperature
- Don’t conduct electricity as there are no free electrons and they aren’t charged
What is different about polymers that are not the same in simple covalent molecules?
The intermolecular forces in a polymer are larger than those in simple covalent molecules, meaning more energy is needed to break them, so they are solid at room temperature even though they use covalent bonding.
Define giant covalent structure
These are called macromolecules where all the atoms are bonded to each other by strong covalent bonds. They never conduct electricity.
Examples: diamond, graphite, silicon dioxide
What are the properties of diamond?
- Four covalent bonds
- Really hard
- Very High melting point
- Doesn’t conduct electricity as there are no free electrons
What are the properties of graphite?
- Three covalent bonds (hexagon shapes)
- In layers with cross links between them
- Soft and slippery
- High melting point
- Each carbon atom has one delocalised electron so it conducts electricity and thermal energy
What are the properties of fullerenes?
- Carbon shaped like closed tubes or hollow balls
- Can be pentagons, hexagons, or heptagons
- Can be used to cage other molecules (deliver drug into body)
- Large surface area (good catalysts)
