Flashcards in Topic 3 - Types of substances Deck (67):
What do atoms always want to have?
A full outer shell.
How are ions formed?
When an atom either gains or loses an electron
What are atoms called that have lost an electron?
What are atoms called that have gained an electron?
What do metals always form? (cat or ani)
Metals always form a cation
What do non-metals always form? (cat or ani)
Non-metals always form an anion.
What does a non metal turn into when ionised?
The non-metals changes to -ide. This tells us its an ion.
What do you need to make sure you include in a dot and cross diagram?
The brackets with either the + or -
Where are metals found on the periodic table?
On the left side
What is the difference between magnesium sulphate and magnesium sulphide?
Magnesium sulphIDE is made up of magnesium and sulphur
Magnesium sulphATE is made up on magnesium, sulphur AND oxygen
What is an ionic compound?
When a metal joins a non metal to ionise
List 3 properties of ionic compounds
- High boiling points/ High melting points
- They don’t conduct as solids but as liquids
- They are metals joined with non-metals
What is the compound ion of carbonate
CO2- ( on top) 3 (on bottom)
What is the compound ion of sulphate
SO 2- (on top) 4 on bottom
What is the compound ion of nitrate?
NO - (on top) 3 (on bottom)
What is the compound ion of hydroxide?
OH - (on top)
What is the compound ion of phosphate?
PO 3- (on top) 4 (on bottom)
How do you know what compound ion an element has?
Depending on what group it is will tell you what group it is in and you need to figure out what it’ll have to do to gain a full outer shell Eg. Magnesium is in group 2 so will be 2+ as it’ll lose two electrons
Why do ionics have high melting points?
Because of the strong electrostatic attraction between ions
Why do ions conduct only as liquids?
Because the ions can move
What is a pair of shared electrons called?
A covalent bond
Write the formula for water
Write the formula for hydrogen
Write the formula for potassium nitrate
Write the formula for calcium carbonate
Write the formula for copper nitrate
Write the formula for aluminium oxide
Write the formula for magnesium oxide
Write the formula for calcium hydroxide
What holds ions together in an ionic bond?
Describe the structure of an ionic lattice.
Regular arrangement of ions. Lots of circles with + and - alternating.
Explain why magnesium chloride has a high melting point.
The strong electrostatic attraction between the oppositely charged ions means it has a high melting point.
Why do ionic substances conduct electricity when dissolved but not when solid?
Because in the liquid the ions can move
Magnesium oxide is insoluble in water. State the condition needed for magnesium oxide to conduct electricity.
Molten/Melted. This means the particles can move around.
What tests would you carry out to see if a substance was ionic?
check if it insulates as a solid and conducts as a liquid
When figuring out the number of protons, neutrons and electrons in something like S2- what does it mean?
It means that it has gained two electrons.
What is the difference between copper sulfide and copper sulfate?
SulphIDE has sulphur
SulphATE has sulphur AND oxygen
Give three main properties of metals
Hard and strong
Describe the structure and bonding in metals.
The positive metal ions are held together by a sea of delocalised electrons. Lots of circles but all +
Why do metals have high melting points?
Because of the strong electrostatic connections between the positive ions and electrons
Why can metals conduct electricity?
Because delocalised electrons can move
Aluminium forms Al3+ ions. Why does this mean it has a higher electrical conductivity than magnesium?
There are more delocalised electrons
What is a molecule?
A molecule is a small group of atoms joined together.
What is the molecular formula of methane?
What is the formula for oxygen?
How are bonds represented in structural formulae?
Using lines. Eg. For methane it’s C in middle and four H’s on each side
Covalent bonds are strong, so why does water have a low melting point?
You only have to break the weak intermolecular bonds
Methane consists of molecules of CH4. Would you expect to have a high or low melting point? Why?
Low. Weak intermolecular bonds.
Describe the structure of diamond.
- Giant covalent structure
- Strong and has high melting points because of its giant covalent structure
- strong covalent bonds
Explain why graphene isn’t a simple molecule.
It has a large sheet of carbon with an unlimited amount of carbon atoms
What is a monomer? How do they make polymers?
Small molecules with a double bond, these then form polymers
Explain why most polymers are solids at room temperature but their monomers are liquid or gases.
Because of the long molecules there are more intermolecular forces
Describe the structure of graphite
Single layer of carbon
A fullerene has the formula C60. Describe its structure and properties.
Soft but can dent diamonds when pressurised
Not very reactive
List two ionic properties
High melting points
They conduct as liquids
List three things about giant covalent substances
High melting point and boiling point
Example: Graphite and diamond
List three things about simple molecular compounds?
Low melting point and low boiling point
Example: water and carbon dioxide
Why do simple molecular substances have low melting points?
Because of the weak intermolecular bonds molecules are broken. Only a small amount of energy is needed to break the weak forces. This means they have low melting points.
Why do giant covalent substances have high melting points?
Because they need more energy to breakaway down he strong covalent bonds.
What is a polymer?
A large molecule containing chains of carbon atoms made from joining many smaller carbon chains
The longer the chain in a polymer...
The more intermolecular bonds so more energy is needed to break the bonds.
What are allotropes?
different structural forms of the same element. Diamond and graphene are both allotropes of carbon. These are giant covalent molecules.
Three properties of giant ionic substances
- high melting point
- conduct as liquids
- metal/non-metal joined
When does covalent bonding happen?
Between two or more non-metals. This is strong.
What is metallic bonding?
Between metals. The electrons are delocalised. Metallic bonding is strong.
What is the only bonding that is weak?