2 Bonding 2 Flashcards
State the melting points of ionic substances
High
Explain why ionic substances have high melting points.
Strong bonds between oppositely charged ions are hard to break
Will NaCl(s) conduct electricity?
No
Will NaCl (aq) conduct electricity?
Yes (aq stands for aqueous which means it is dissolved in water)
Will NaCl (l) conduct electricity?
Yes
What does molten mean?
Melted
Explain why ionic compounds do not conduct electricity when solid
Because the ions are not free to move
Explain why ionic compounds conduct electricity in solution
Because the ions are free to move
Explain why ionic compounds conduct electricity when molten
Because the ions are free to move
What does soluble mean?
Dissolves in water
What does insoluble mean?
Does not dissolve in water
Magnesium carbonate is insoluble. What do you need to do before it will conduct electricity?
Melt it
Sodium fluoride is soluble. Explain what the easiest way for it to conduct electricity is
Dissolve it in water because this does not require high temperatures
Explain why chlorine and fluorine form covalent bonds
They are both non-metals
Complete the sentence: In covalent bonds, electrons are _______________________
Shared
In ionic bonds, electrons are ___________________
Transferred
What is the name given to the structure of diamond, graphite and silicon dioxide?
Giant covalent
How many bonds does each carbon have in diamond?
4
Explain why diamond has a high melting point
Giant structure, Strong covalent bonds between the atoms, requires a lot of energy to break
Explain why most giant covalent substances do not conduct electricity (3 marks)
There are no electrons/ions/charged particles that are free to move
Explain why graphite conducts electricity
Has delocalised electrons between the layers that can move through the graphite
Explain why graphite can act as a lubricant
Weak forces between layers which are free to slide over each other
What is graphene?
One layer of graphite
What is a fullerene?
Substance made of carbon atoms arranged in a cage
What type of substance are methane and water?
Simple molecular (or simple molecules)
What is a molecule?
A group of atoms chemically bonded together
Describe the structure of simple covalent molecules
Strong covalent bonds between atoms, weak forces holding the molecules together
What are intermolecular forces?
Weak forces between molecules which hold them together
Explain why methane has a low melting point
It is a simple molecular substance with weak forces between the molecules (which are easy to break)
What is a polymer?
Millions of small molecules joined together in a chain to form a large molecule
