Different structures Flashcards
Describe a simple molecular structure
Simple molecules contain only a few atoms held together by covalent bonds.
Describe a giant ionic structure
Giant ionic lattices are a regular structure held together by strong ionic bonds
Describe giant covalent structure
Contains many atoms and all of them are linked together by strong covalent bonds
Describe giant metallic structure
A lattice of metal cations surrounded by lots of delocalised electrons
What type of substances have simple covalent structure?
Simple covalent molecules like water
What type of substances have giant ionic lattice structure?
Ionic compounds like sodium chloride
What type of substances have giant covalent lattice structure?
Giant covalent substances like diamond
What type of substance has giant metallic structure?
Metals and alloys
Why do ionic substances have high melting points?
Because they are held together by string electrostatic forces of attraction between oppositely charged ions. Ionic substances have a high melting point because of the large amount of energy needed to overcome the ionic bonds.
Why do simple molecular substances have low melting points
The intermolecular forces of attraction are weak and very little energy is needed to overcome them.
Why do giant covalent substances have very high melting points?
They are made up of lots of covalent bonds between atoms. They have a high melting point as it takes a lot of energy to overcome the strong covalent bonds between the atoms.
Why do metallic substances have high melting points?
The string electrostatic force of attraction between the positive ions and delocalised electrons is what forms the strong metallic bond. These bonds are very strong and require a lot of energy to break meaning they have very high melting points.
Why do ionic substances conduct electricity when molten or dissolved but not when solid
When the ionic substance is molten or dissolved, the ionic lattice is broken down allowing the ions to move freely so there are delocalised electrons free to carry a charge.
