Bonding, Structure And The Properites Of Matter Flashcards
Name the three types of bonds
Ionic
Covalent
Metallic
What is ionic bonding?
The attraction between positive and negative ions. Ionic substances
What is covalent bonding?
Atoms joined together by sharing pairs of electrons
Molecular substances and giant covalent substances
What is metallic bonding?
The attraction between the positive nuclei of metal atoms and delocalised electrons
Metallic substances
Describe the structure of ionic substances
All solids at room temperature and the positive and negative ions are arranged in a giant lattice. There is a strong attraction between the positive and negative ions as opposite charges attract
Describe and explain the properties of ionic substances
Melting and boiling points- high because there is a strong attraction between the positive and negative ions
Do not conduct electricity when solid as the ions cannot move
Do conduct electricity as liquids or when dissolved as ions can move through the substance
Name the four ways the structure of ionic compounds can be shown
Dot and cross diagram
2d space-filling structure
3D space filling structure
Ball and stick structure
What are the advantages of dot and cross diagrams when representing ionic compounds?
Shows the electron structure of the ions
Name the disadvantages of using dot and cross diagrams to represent ionic compounds
Can give the impression that the structure is made of pairs of ions rather than being a continuous structure containing a massive number of ions
Advantages of 2d space filling structure. Ionic compounds
Very easy to draw
Disadvantages of using 2d space filling structure
Looks like structure only contains few ions
Only shows structure in 2d
what are the advantages of 3D space filling structure when representing ionic compounds?
Gives very good representation of how ions are packed together
what are the disadvantages of 3D space filling structure when representing ionic compounds?
Looks like the structure is limited to few ions
Advantages of ball and stick structure when representing ionic compounds
Helps to show how ions are arranged relative to each other
Disadvantages of ball and stick representation of ionic compounds
Gives impression that structure is limited to a few ions
May look like there are covalent bonds ( there are NO COVALENT BONDS in ionic lattice)
Describe the structure of molecular substances
The covalent bonds holding the atoms together within each molecule are very strong. However, molecules are no bonded together and there are only wrk forces between the molecules
What are molecules?
Particles made from two or more atoms joined by covalent bonds
What are the properties of molecular substances? And why?
Low Melting and boiling points because weak forces between molecules need little energy to overcome
Do not conduct electricity as they do not contain any delocalised electrons or ions
When is a covalent bond formed?
When two shared electrons join atoms together
What is a polymer?
Long chain molecule made from joining lots of short molecules together
What is it like in a thermosoftening polymer?
The polymer chains are not joined together. This means that they will soften and melt on heating. They are solids at room temperature because the forces between the molecules are relatively strong as they are big molecules
What is a macromolecule?
A very long molecule
What is the structure of giant covalent structures?
Joined by covalent bonds in one giant continuous network
Giant lattice
What are the properties of giant covalent substances?
Very high melting and boiling points because covalent bonds have to be broken
Most do not conduct electricity as they do not have delocalised electrons that are free to carry charge
Graphed and graphite do conduct electricity as they contain some delocalised electrons
Describe the structure of metallic substances
Giant lattice of atoms, but the outer shell electrons are delocalised from each atom
Strong attraction between the positive nucleus of the metal atoms and the negative delocalised electrons (this is called metallic bonding)
Describe the melting points of metallic substances
High because the attraction between the positive nucleus of the metal atom and the negative delocalised electrons is strong
Describe the electrical and thermal conductivity of conductivity
They conduct because the outer shell electrons are delocalised and can carry charge through the metal
Describe the malleability of metallic substances
They are malleable because the atoms can slide over each other while maintaining the metallic bonding
What are pure metals too soft for many uses?
Malleable
What is an alloy?
A mixture of a metal with small amounts of other metals or carbon added
Why are alloys harder than pure metals?
They contain some atoms that are a different size and so it is more difficult for atoms to slide past each other
Name the three states of matter
Solid
Liquid
Gas
Why is the traditional model of particles in solids, liquids and gases limited?
It does not show the forces or bonds between the particles
They could be molecules or ions
The stronger the _________ or __________ between the particles, the higher the melting and boiling points
Forces or bonds
What is a nano science?
The study of nanoparticles which are between 1-100nm in size
What is 1nm in metres?
1nm = 1 x 10^-9m
How is a nanoparticle of gold different to bulk gold?
Bulk gold is yellow and interactive but nanoparticles of gold are red and are very reactive
Bulk gold is one large structure made of huge number of atoms but a nanoparticle of gold is much smaller with a few hundred atoms
Nanoparticles have a higher surface area to volume ratio
Name some used of nanoparticles
To deliver drugs to specific cells in the body Suncreams Cosmetics Deodorants Electronics Catalysts
Why is there concerns about the safety of nanoparticles?
Different properties to bulk material
Name 4 different forms of carbon
Diamond
Graphite
Buckminsterfullerene
Graphene
Describe diamond
Giant covalent structure A lattice of atoms joined by covalent bonds Very high melting points Insulator Very hard and strong Each C atom has 4 bonds
Used as cutting tools
Describe graphite
Giant covalent structure A lattice of atoms joined by covalent bonds Each C atom makes 3 bonds Atoms in flat layers but weak forces between layers Very high melting points Conductor Soft and brittle Used as electrodes and pencils
Describe buckminsterfullerene
Simple molecular
Made up of many molecules each molecule Contains 60 carbon atoms
Each C atom makes 3 bonds
Low melting points
Insulator- has delocalised electrons but cannot move
Soft and brittle
Used in drug delivery and lubricants
Describe graphene
Giant concealment structure Lattice is atoms joined by covalent bonds. Each C atom makes 3 bonds Very high melting points Conductor Very strong Used as electronic components
