Ionic, Covalent And Metallic Bonding Flashcards
Define Ions
Ions are particles with a charge
Name of a positively charged ion
Cation
Name of a negatively charged ion
Anion
Forming of Ionic Compounds
Formed between metals and non metals.
Metals transfer there outer shell electron to non metals.
Forming positive metal ions and negative non metal ions.
Oppositely charged ions…
Are attracted to each other
Ionic Compounds: Structure and Properties
-High Melting Points
- High Melting Points
Many strong attractions between oppositely charged ions that take a large amount of energy to break.
NaCl = 801•C melting point
MgO = 2852•C melting point
Magnesium Oxide has a 2+ and 2- which attract a lot stronger that Sodium Chloride which has a + and - which don’t attract as strongly.
Ionic Compounds: Structure and Properties
- Explain their Electrical Conductivity
Ionic Compounds do not conduct electricity as a solid because the ions are in fixed positions.
Ionic compounds DO conduct electricity as a molten liquid or in aqueous solution because the ions can move.
Define Electrolysis
Electrolysis is the decomposition of a compound into its elements using an electrical current.
Electrolysis of Molten PbBr2 (Lead Bromide)
The cations (Pb2+) will be attracted to negative electrode.
The anions (Br-) will be attracted to positive electrodes.
2Br1- ->Br2 + 2e- (Oxidation)
Bromide ions lose electrons to form bromine atoms and then bromine Br2 molecules.
Pb2+ +2e->Pb (Reduction)
Lead ions gain electrons to form lead atoms and then lead Pb molecules.
OILRIG
Oxidation
Is
Loss of electrons
Reduction
Is
Gain of Electrons
Electrolysis of Aqueous Copper Chloride
Positive Cu2+ ions were attracted to the negative electrode where they gained electrons in a reduction ion reaction.
Cu2+ + 2e- ->Cu
The negative Cl- ions were attracted to the positive electrode where they lost electrons in an oxidation reaction.
2Cl->Cl2 + 2e-
Uses of Electrolysis
- Purifying metals
(Only for metals less reactive than hydrogen) - Electroplating
(Only for metals less reactive than hydrogen) - Electrolysis of Brine
Describe Covalent Bonding
Not ionic.
Outer shell electrons are shared in order to achieve a full outer shell. This is bonding between non metals.
E.g. CO2
A covalent bond is formed by the electrostatic attraction of two nuclei that are both attracted to a shared pair of electrons.
Covalent Bonding No. of Bonds
Group No. in out shell No. of bonds E.g
7. 7. 1. Cl,F
6. 6. 2. O,S
5. 5. 3. N
4. 4. 4. C,Si
Hydrogen forms one bond.
What is a Simple Molecular Substance
A molecule contains 2 or more atoms that are covalently bonded together, has formula to show exactly how many atoms in a molecule.
E.g. Cl2, H2O, C6H12O6
Properties of Simple Molecular Substances
- Low Melting and Boiling Points, often gases or liquids at room temp. Molecules held together by weak attractions called inter-molecular forces which require little energy to break.
- Do not conduct electricity as a solid or when molten. THEY HAVE NO IONS AND NO FREE MOVING ELECTRONS
What is a Polymer
A polymer is a very long chain molecule.
When a molecule is very large, intermolecular forces are stronger due to the large mass the large surface area to volume ratio of the molecule.
They are solid at room temp.
Describe Thermosetting Polymers
Cross links between chains, so do not soften/melt on heating. They char/burn when heated.
Due to strong covalent bond between chains.
Describe Thermosoftening Polymers
Soften/melt on heating.
Due to weak forces between chains
Crio bonds between chains.
Structure of Diamond
Each cation is covalently bonded to 4 other cations.
Diamond has a very high melting point because there are a huge number of strong covalent bonds that takes a lot of energy to break.
There are no free electrons, there are no ions, so diamond does not conduct electricity as a solid or liquid.
Structure of Graphite
Graphite is made up of layers of hexagons where each C is covalently bonded to 3 other carbons.
Outer shell electrons per C become delocalised.
This can move through the structure carrying charge and making a current.
Hence solid graphite will conduct electricity.
The melting point is very high for the same reason as diamond.
There are weak forces between layers so layers will slide past each other each other easily making graphite a slippery lubricant.
Give some other Giant Covalent Structures not containing carbon
Silicon (Si)
Silicon Dioxide (Si02)
Both silicon and silicon dioxide have similar properties for same reasons as diamond.
Allotropes of Carbon
Diamond, Graphite, Buckminsterfullerene, Graphene, Nanotubes
Describe the structure of Buckminsterfullerene
Simple molecular structure
E.g. C60
3 covalent bonds to each atom
Not very high melting/boiling points.
-Need to overcome relatively weak forces between molecules.
Insulator
-Has delocalised electrons but they cannot move.
Soft and brittle
Describe the structure of Graphene
Giant covalent structure. Single layer
3 covalent bonds to each atom.
Very high melting/boiling points.
-Need to break strong covalent bond.
Conductor
-Delocalised electrons that can carry charge through structure.
Soft and Brittle
Nanotubes
An allotrope of carbon.
High surface area to volume ratio.
Conductors
What is Nanoscience
Study of nano particles.
A nano particle is between 1 and 100 nm in size.
Properties of Nanoparticles
Different properties to bulk material.
E.g. a nano particle of silver dif properties to large lump of silver.
This is because a nano particle has a much greater surface area to volume ratio.
Uses of Nanoparticles
Makes Clothes hydrophobic
Fullerenes can specifically target cancers and not have significant side affects.
New way to collect heat energy (1x10^25 of the size of human hair so can collect infra red radiation.
Problems with Nanoparticles
Can potentially have harmful effects.
If they get inside our body or upon an ecosystem.
What happens in Metallic Bonding
In metallic structure the metal atoms lose there outer shell electrons to form positive ions that are arranged in layers in a giant lattice surrounded by a sea of delocalised electrons.
Definition of Metallic Bonding
A metallic bonding is the electrostatic attraction between the layers of positive metal ions and the delocalised electrons.
3 Types of Bonding
Metallic: Only contains metal atoms
Covalent: Contains only non-metal atoms.
Ionic: Contains non-metal and metal atoms.
Definition of Alloys
Alloys are a mixture of a metal with small amounts of other elements.
Benefit of Alloys
Pure metals are soft but alloys are much harder. Layers cannot Slide Over each other so easily as atoms are different sizes.
Examples of Alloys
Bronze: Copper + Tin
Used in statues.
Aluminium Alloys: Aluminium + Magnesium
Used in planes.
Brass: Copper + Zinc
Kills bacteria
Instruments
Door handles
Gold Alloys: Gold + Silver/Copper/Zinc
Pure gold = 24 carat
What are the 2 types Steels
Carbon Steels
Stainless Steels
Carbon Steels
These differ in hardness, the more carbon is used, the harder the steel.
More brittle the higher C
Stainless Steels: Benefits
Add:
Chromium - Resistant to corrosion
Cobalt - Can strongly magnetise
Molybdenum- Strong and tough
Nickel - Resistant to chemical attack by acids
Tungsten - Strong at high temps
Vanadium - More springy , less brittle
