COVALENT BONDING Flashcards
(20 cards)
When a substance consisting of small molecules is melted or boiled, identify the forces that are overcome
IMF
Explain why polymers have high melting points relative to substances made of small molecules
They have much larger molecules
So stronger IMF
which require more energy to overcome
Describe the structure of graphite
Each carbon atom from three covalent bonds with three other carbon atoms
The atoms form layers made of hexagonal rings
Explain why Diamond is hard
It has a giant covalent structure
It has strong covalent bonds between atoms
Which are hard to break
Describe what happens to electrons in covalent bonding
Electrons are shared between atoms
Explain why graphite can act as a lubricant
There are no covalent bonds between the layers
So they are free to slide over each other
Give 2 typical properties of substances made of small molecules
Low melting and boiling points
Do not conduct electricity
Give 3 examples of of substances that consist of small molecules
Oxygen, water and ammonia
Explain why Diamond has a high melting and boiling point
It has a giant covalent structure
It has strong covalent bonds between atoms
Which require a lot of energy to overcome
Explain why larger molecules have higher melting and boiling points than smaller ones
They have stronger IMF
which require more energy to overcome
Give 3 examples of substances with a giant covalent structure
Diamond, silicon dioxide and graphite
Name the type of structure that is made of billions of atoms covalently bonded together
Giant covalent bond
Define polymer
A very large molecule consisting of smaller molecules joined together
Name the type of substances that form covalent bonds when they react together
Non metals
Explain why graphite conducts electricity , making full reference to its structure and bonding
Each carbon atom has 3 bonds only
There is therefore one delocalised electron per carbon atom
The delocalised electrons are free to carry charge through the graphite
How many carbon bonds does each carbon atom have in diamond?
4
Name the 3 main types of substance formed from covalently bonded atoms
Small molecules, very large molecules and giant covalent structures
Name the typical state that substances made of small molecules are at room temp
Liquid or gas
Describe the structure of substances consisting of small molecules
Small molecules made up of atoms held together by strong covalent bonds
Weak IMF act between the molecules
Describe the relationship between the size of a molecule and the strength of its IMF
The larger a molecule, the stronger it’s IMF
