Topic 2 Using Spec Flashcards
What happens when an atom loses one or more electrons
It becomes a cation - a positively charged ion
What happens when an atom gains one or more electrons
Becomes an anion - a negatively charged ion
How are ionic bonds formed
When the transfer of electrons occurs an electrostatic attraction between the two ions of opposite charge takes place and an ionic bond is formed.
What is an ion
An ion is an atom or group of atoms with a positive or negative charge .
When do materials with ionic bonds conduct electricity
When molten and high melting points
When do ionic compounds end in -ide
When made from 2 different elements
When do ionic compounds end in -ate
When the ionic compound is made from 3 or more different elements
Explain the structure of an ionic compound as a lattice structure
Oppositely charged ions are held together in ionic lattices. Ionic lattices are giant structures that are held together by strong electrostatic forces between the positive and negative ions.
Deduce the formula for sodium carbonate.
Sodium carbonate contains Na+ and CO32- ions:
this is one positive charge and two negative charges
to balance, two Na+ ions and one CO32- ions are needed
so the formula is Na2CO3
Explain how a covalent bond is formed when a pair of electrons is shared between two atoms
Covalent bonds are formed when 2 non-metal atoms share pairs of electrons.
These electrons are found on the outer shell of the atoms. Covalent bonds are strong because the shared electrons are attracted to the nucleus of both atoms
covalent bonding results in the formation of what molecules?
Small molecules (water) Large molecules (polymers) Giant covalent structures (diamond)
What kind of covalent bond is hydrogen
Single covalent bond as each hydrogen atom shares 1 electron with the other
What kind of covalent bond is water
Single covalent with 2 hydrogen atoms
What type of covalent bond is oxygen
Double covalent bond as it needs 2 electrons to get a full outer shell
What are the properties of the lattice structure in the ionic compounds
High melting and boiling points
Don’t conduct electricity if solid
Conduct electricity if liquid or in solution
Why do lattice structures have a high melting and boiling point
Because to break the ionic bonds, a lot of energy is needed to overcome the electrostatic forces between the ions and electrons.
Why can’t the lattice structure conduct electricity if solid
When solid the ions are fixed in place therefore charges cannot flow so electricity cannot be conducted
Why can the lattice structure conduct electricity if liquid or in solution
When molten or dissolved in water, the ions in the lattice can move freely therefore charges can flow and electricity can be conducted
What is an example of a small molecule
Chlorine as it has weak intermolecular forces between its molecules
What is an example of a bigger molecule
Sucrose as its intermolecular forced are strong
What are the properties of small covalent molecules
Lower melting/boiling points
Don’t conduct electricity
What are the properties of large covalent molecules
High melting/boiling point
Don’t conduct electricity
Why are small covalent molecules liquid or gases at room temperature
When small molecules melt or boil, it’s the weak intermolecular forces that break.
Since these intermolecular forces are weak and break easily, simple covalent molecules have very low melting and boiling points.
Therefore, they exist as liquid and gases at room temperature.
What are the properties of giant covalent structures
Very high melting points
1 large molecule
Why does giant covalent structures have very high melting points
As the string covalent bonds between atoms make them solid at room temperature
High temperatures and significant energy are required to break the structures covalent bonds
Why is 1 large molecule a property of giant covalent structures
There are no intermolecular forces because there is only 1 molecule
What are some example of giant covalent structures
Graphite and diamond
Explain why elements and compounds can be classified as metallic
As they only have a few atoms
Explain why elements and compounds can be classified as ionic
As the Ionic compounds contain ions and are held together by the attractive forces among the oppositely charged ions.
Explain why elements and compounds can be classified as simple molecular
Simple molecules contain only a few atoms held together by covalent bonds
What is diamond
An allotrope of carbon
What are the properties of diamond
Covalent bonds
High melting point
Hard
Does not conduct electricity
Describe the covalent bonds in diamond
Each carbon atom is bonded to 4 other carbon atoms by strong covalent bonds which creates a giant covalent structure
Why does diamond have a high melting point
Lots of strong covalent bonds so requires a lot of energy to break the bonds
Why is diamond hard
Lots of strong covalent bonds
Why does diamond not conduct electricity
As there are no delocalised electrons
Why are graphite and diamond different types of carbon
Graphite conducts electricity as there is one delocalised electron from every carbon atom
Diamond is hard whereas graphite is soft
Each carbon atom in graphite is bonded to 3 other carbon atoms by strong covalent bonds.
Why is graphite useful as a lubricant and as pencil lead
As the layers can easily slide over one another as the intermolecular forces keeping the layers together are weak so graphite is very soft
Why is diamond used for cutting tools
As diamond is very hard due to its strong covalent bonds
What is fullerenes
Molecules of carbon atoms that take up hollow structures
Describe the structure of fullerenes
Carbon atoms arranged in a hexagonal rings but pentagonal and heptagon all rings can be found as well
What was the first fullerene to be discovered
Buckiminsterfullerane - spherical shape and formula c60
What are the properties of graphene
Conducts electricity- each carbon atom has a delocalised electron
Light but strong- almost a two dimensional structure but has strong covalent bonds between carbon atoms
What can graphene be used for
Solar panels
Batteries
What are polymers
Large chain like molecules
Held together by strong covalent bonds between atoms in molecules
Weak intermolecular forces between molecules
Why do many polymers melt easily
The intermolecular forces remain less strong than chemical bonds
What is poly (ethane)
An addition polymer
What are the properties of pure metals
Soft and malleable- ions are arrange in layers that easily move over each other when a force is applied
High melting and boil point strong electrostatic forces between metal ions and delocalised electrons.
What are the advantages and disadvantages of dot and cross model
Pro - shows the bonding
Con - doesn’t show how the ions are arranged in space
Ball and stick advantages and disadvantages
Pro - illustrates arrangement of atoms in 3D space
Con - doesn’t show movement of electrons
2-3 dimensional representation model advantages and disadvantages
Pros - Shows how much space and atom uses
Con- hard to see structure of whole molecule clearly
Properties of non metals
Low boiling points
Poor conductors of electricity
