Unit 2 Structure and Bonding Core questions Flashcards
When does ionic bonding occur?
When a metal and non-metal react
When does covalent bonding occur?
When non-metals react
When does metallic bonding occur?
When metals react
What is an ionic bond?
The electrostatic attraction between oppositely charged ions
What is a covalent bond?
The electrostatic attraction between the positive nuclei of atoms and the shared, negative electrons between them
What is a metallic bond?
The electrostatic attraction between positive metal ions and the delocalised electrons
What charge will an ion of lithium have?
1+ (one electron in the outer shell, needs to lose it)
What charge will an ion of beryllium have?
2+ (two electrons in the outer shell, needs to lose them both)
If something has gained electrons, what charge will it have?
Negative
If something has lost electrons, what charge will it have?
Positive (because they have lost a negative!)
What charge will an ion of oxygen have?
-2 (6 electrons in outer shell so needs to gain two)
What charge will an ion of Selenium have?
-2 (group 6, so has 6 electrons in the outer shell and needs to gain two)
Explain in terms of electrons what occurs when lithium bonds with chlorine
One electron lost from lithium and it is gained by chlorine
Why do atoms transfer electrons in ionic bonding?
So that they can have full outer shells
Explain in terms of electrons what occurs when lithium bonds with fluorine
One electron lost from lithium and it is gained by fluorine
Explain in terms of electrons what occurs when magnesium bonds with oxygen
Two electrons lost from magnesium and they are both gained by oxygen
Explain in terms of electrons what occurs when beryllium bonds with oxygen (3 marks)
Two electrons lost from beryllium and they are both gained by oxygen
Explain in terms of electrons what occurs when magnesium bonds with chlorine
Two electrons are lost from magnesium and two different chlorine atoms each gain 1 electron
Explain in terms of electrons what occurs when sodium bonds with oxygen
two different sodium atoms lose one electron and an oxygen atom gains both
Why don’t sulphur ions and oxygen ions form ionic bonds with each other?
Both have negative charges so would repel
What is the name for the structure of a solid ionic compound?
Giant ionic lattice
Define giant ionic lattice
A huge 3D network of ions
State the melting points of ionic substances
High
State the melting points of ionic substances
High
Explain why ionic substances have high melting points
Strong ionic bonds between oppositely charged ions require lots of energy to break
Will a solid ionic compound conduct electricity and why?
No, because the ions are held firmly in place
Will a molten ionic compound conduct electricity?
Yes, as the ions are free to move so can carry a charge
What does molten mean?
Melted
What does (aq) stand for?
Aqueous, which means dissolved in water
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
What happens in covalent bonding?
Atoms share a pair of electrons
How many covalent bonds will a group 7 element make?
1 as they need one more electron for a full outer shell
How many covalent bonds will a group 6 element make?
2 as they need two more electrons for a full outer shell
How many covalent bonds will a group 5 element make?
3 as they need three more electrons for a full outer shell
How many electrons does hydrogen have when it has a full outer shell?
2 as the first shell only holds 2 electrons
How many covalent bonds does hydrogen make?
1 as it only needs one more electron for a full outer shell. It also only has 1 electron to share!
In ionic bonds, electrons are ___________________
Transferred from a metal atom to a non-metal
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
It has a giant covalent structure. The strong covalent bonds between the atoms require a lot of energy to break
Explain why most giant covalent substances do not conduct electricity (3 marks)
There are no mobile electrons/ions to carry a charge
Explain why graphite conducts electricity
Carbon only makes 3 bonds, each carbon has a delocalised electron that can move through the graphite
Explain why graphite can act as a lubricant
Layers of atoms can 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 covalent 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 intermolecular forces between the molecules
What are intermolecular forces?
Weak forces between molecules which hold them together
Explain why molecular substances have a low melting point?
Weak intermolecular forces between the molecules which require little energy to break
What is a polymer?
Millions of small molecules called monomers joined together in a chain to form a large molecule
Describe the structure of metals
Positive metal ions arranged in layers with delocalised electrons
Explain why metals can conduct electricity
Have a delocalised electrons can carry a charge
Explain why pure metals are soft
Layers of metal ions can slide over each other
What is an alloy?
A mixture of two or more elements, at least one of which is a metal
Give a reason for alloying a metal
To make it harder
To make it less reactive
Explain why alloys can be harder than pure metals
Different size of atoms disturb the layers to stop them sliding over each other
Why do metals conduct heat?
Delocalised electrons can move and transfer energy
What happens at the melting point?
A substance goes from solid to liquid or from liquid to solid
What happens at the boiling point?
A substance goes from liquid to gas or from gas to liquid
What is a nanoparticle?
A particle between 1 and 100 nm in size
Why are nanoparticles useful?
They have a high surface area to volume ratio. This means they have unique properties and smaller quantities are needed to be effective
What are some uses of nanoparticles?
They are used in medicine, electronics, cosmetics, sun creams, deodorants and as catalysts.
What are some risks of nanoparticles?
They are still new so haven’t been studied in detail yet and they may cause harmful effects to the human body
