C3 Structure And Bonding Flashcards
Process of melting
As solid is heated particles gain energy and vibrate more
As temperature increases when it reaches melting point there’s enough energy to break free from their positions
This is called melting when solid becomes liquid
Process of freezing
Liquid turns to a solid as a result of lowered energy in particles
Result of colling to point where liquid solidifies
Process of boiling
When liquid heated particles gain more energy
Energy makes particles move faster which weakens and breaks the bonds holding liquid together
When it reaches the boiling point the particles have enough energy to break their bonds
Process of condensing
As gas cools particles no longer have enough energy to overcome the forces of attraction between them
Bonds form between the particles
At boiling point so many bonds have formed between the gas particles the gas becomes liquid
How do particles act at melting point
Particles start to move about staying close to other particles
Then move freely
How do particles behave at its boiling point
Particles gain energy to overcome bonding forces
They become free, fast moving, individual particles in a gas
Solid to liquid
Melting
Liquid to solid
Freezing
Liquid to gas
Evaporating
Gas to liquid
Condensing
Solid to gas
Sublimation
Gas to solid
Deposition
Why substances have different melting and boiling points from each other
The stronger the forces between particles, the higher its melting and boiling points
The factors that affect rate of evaportaion
Temperature
Surface area
Wind speed
Humidity
The particles involved in ionic bonding
Cation
Anion
When is ionic bonding formed
When a metal loses an electron or gains electrons
Cation
Anion
Cation - a metal which loses electrons
Anion - a non-metal gains electrons
How electron transfer allows ionic bonding to occur in the compound formed when a Group metal reacts with a Group 7 non-metal
Metals lose electrons to become positively charged ions
non‐metals gain electrons to become negatively charged ions
What do opposite charges do
Attract
With an example, how a Group 7 non-metal atom becomes a negative ion
-
Fluorine will gain an electron forming F
Suggest the charge on unfamiliar ions using the position of the element in the periodic table
Elements on left metals form positive ions
Those on the right non-metals form negative ions
Charges of ions of Groups 1-7
Group 1 = 1+
Group 2 = 2+
Group 3 = 3+
Group 4 = 4-
Group 5 = 3-
Group 6 = 2-
Group 7 = 1-
How unfamiliar elements become ions
Atoms lose electrons to form positively charged ions
Ratio of metal and non- metal ions in compounds
2:1
Ionic lattice
Regular repeating arrangement of ions
Properties of ionic compounds
High melting points
Can conduct electricity when molten or dissolved in water
Why ionic compounds have a high melting point
Large amounts of energy needed to break the many strong bonds
Ionic bond
Forms between metal and non-metal
Covalent
Non-metals
The movement of ions in solutions or when molten
Free to move
How a covalent bond forms in terms of electronic structure
When pairs of electrons are shared by atoms
How double and triple covalent bonds can be formed
If 2 pairs of electrons are shared forms double bond
If 3 pairs of electrons are shared forms triple bond
Examples of covalent bonds
H2O
CO2
NH3
Examples of ionic bonds
Sodium chloride
Sodium bromide
Sodium iodide
Metallic bond examples
Na
Al
Mg
How the properties of a double bond could be different to the properties of a single covalent bond
Double bonds are stronger than single covalent bonds
Properties of small molecules
Low melting and boiling points
Don’t conduct electricity
Phyiscal properties of covalent bonds
Low boiling/melting points
Soft
Don’t possess electrical conductivity
Why small molecules and polymers do not conduct electricity
Small molecules have no overall electric charge
Intermolecular force
Forces of attraction between particles
How to identify substances that would have weak intermolecular forces
If it has low boiling point
Physical properties of graphite
High melting and boiling points
Good conductors of heat and electricity
Soft
Phycial properties of diamond
Hard
Giant covalent structure
High melting and boiling points
Bad conductor of electricity
Good conductor of heat
Properties of giant covalent structures
High melting points
Do not conduct electricity as no overall charge
A use for graphite based on its properties
Used as a lubricant for fast-moving parts of machinery
Structure of graphite
Giant covalent structure
Each carbon atom forms 3 covalent bonds creating sheets of carbon atoms arranged in hexagons
Carbon atoms form layers with hexagonal arrangement of atoms with weak forces
There aren’t any covalent bonds between the layers
Only 3 out of carbon’s 4 outer electrons are used in bonds so each carbon atom has 1 delocalised electron
Use for diamond
Embedded into saw blades
Relationship between graphite and graphene
Graphite is made up of hundreds of thousands of layers of graphene
Structure of a fullerene
Hexagonal rings of carbon atoms joined by covalent bonds but can also contain pentagons or heptagons
Uses of fullerenes
Drug delivery in the body
Sports equipment (tennis racket)
Antioxidant
Main physical properties of fullerenes
Good conductors of heat and electricity
Very strong
Highly ductile
Molecular formula of buckminsterfullerene
C60
Use of graphene
Construction
Health
Electronics sector
Use of nanotubes
Used in electronics
Strengthen materials without adding much weight
Used in space and aircraft to reduce the weight and stress of the various components working together
Nanotube
Tiny carbon cylinders
What structures do metals form
Giant structure
Metallic bonding
Bonding from electrostatic attractive forces between conduction electrons
How metal atoms form giant structures
The electrons in the outer shell of metal atoms are delocalised and so are free to move
Physical properties of metals
Malleable
Ductile
Good conductors of heat and electricity
Lustrous (shiny)
Strong
How alloying affects the structure and bonding in metals and its effect on properties
The smaller or bigger atoms distort the layers of atoms in the pure metal
Making it harder them to slide over each other
Pure metals
Metals that have not been alloyed with other metallic elements
Structure of pure metal
Giant metallic structure
Why metals are alloyed
Increase strength
Reduce costs
Increase corrosion resistance
Harder
Nanoscience
The study of structures between 1 and 100 nanometres in size
Size of nanoparticles
1 to 100 nanometres
How to classify a particles as coarse, fine or nanoparticles based on their size
Fine = diameter of 100nm to 2500nm
Coarse = diameter of 2500nm to 10,000nm
How surface area to volume increases as particle size reduces
The surface area to volume ratio increases as the radius of the sphere decreases
Uses of nanoparticles
Paints
Cosmetics
Sunscreens
Advantages of using nanoparticles
Increased strength
Increased durability
Enhanced catalytic activity
Disadvantages of using nanoparticles
Difficult to manufacture
Very small
Very expensive
Why nanoparticles can have new applications
Produces stronger and lighter wind turbines
Imrpoves fuel efficiency
Can save energy
Why nanotechnology research should continue
Can be used for the development of newer materials with better properties
Explain why chlorine (Cl2) is a gas at room temperature, but sodium chloride (NaCl)
is a solid at room temperature
There are weak attractions between molecules of Cl2 so little energy is needed to break these forces of attraction
Why metals are good conductors of heat and electricity
Due to the metallic bonding
In metallic bonding outer electrons are delocalised
The delocalised electrons carry electric charge and thermal energy through the whole structure
Iron reacts with halogen in gaseous form give 1 reason why the experiment should be done in a fume cupboard
Both the reactants and products are hazardous
Why is it not correct to say the boiling point of a single bromine molecule is 59 degrees
Boiling point is a bulk property of a substance and is not applicable to individual molecules
Why C70 molecules is good for the uses in medicine to move drugs from around the body
It is hollow
Why diamond has a very high melting point
4 valence electrons surrounding each carbon atom which are strong covalent bonds making them hard to break. Requires very high energy to break
Element dull solid with melting point 44
Does not conduct electricity
Where most likely found on periodic table
Far right end
Buckminister fullerene
A fullerene with formula C60 with a cage-like structure made of twenty hexagons and twelve pentagons
Avogadro’s number of C70
21
8.6 x 10
How to work out molar mass
Moles of 1 reactant
_________________________
Moles of other reactant
How are opposite charged ions strongly attracted to each other
Electrostatic force
This attraction is called an ionic bond
What arrangements do ions form
Regular lattice
Regular lattice structure
Strong electrostatic forces of attraction between oppositly charged ions in all directions of lattice
Structure of a single sodium chloride (salt)
Giant ionic lattice
Why can ion not conduct electricity when a solid but can when molten or dissolve in water
Not free to move in a solid
When ionic compound molten or dissolve in water the ions are free to move so they’ll carry an electric charge
Empirical formula
The simplest whole number ratio of atoms in each elements in a compound
What do all covalent bonds provide
1 extra shared electron for each atom
Where does covalent bond happen
In compounds of non-metals
What are simple molecular substances made up of
Molecules containing a few atoms joined together by covalent bonds
Structure of simple molecular substance
Atoms held together by strong covalent bonds
Forces of attraction between these molecules are very weak
Why are boilng/melting points of simple molecular substances very low
Molecules easily parted from each other
What state are most simple molecular substances at room temperature
Gases or liquids
What happens as molecular substances get bigger
The strength of intermolecular increases so more energy needed to break them so melting and boiling points increase
Why don’t molecular compounds conduct electricity
They aren’t charged so there are no free electrons or ions
What bonds do polymers have
Covalent bonds
Polymers
Large molecules made up of repeating units called monomers
What are polymers used for
Plastic bags
Ropes
Water pipes
Properties of polymers
Strong
Low density
Waterproof
Why do polymers have low melting/boiling points
Intermolecular forces are weak
Why are most polymers solid at room temperature
Intermolecular forces are larger between polymer molecules than in between simple covalent bonds so more energy needed to break them making them solids
Structures of polymers
Large molecule made up of repeating units known as monomers
All atoms joined by strong covalent bonds
Molecular formula of polymer poly(ethene)
(C2H4)n
Examples of polymers
Nylon
Epoxy
Teflon
Describe giant covalent structure
All atoms bonded together by strong covalent bonds
High melting boiling points as lots of energy needed to break bonds between atoms
Don’t conduct electricity
Why don’t giant covalent structures conduct electricity
They don’t contain charged particles
Examples of giant covalent structures
Diamond
Graphite
Structure of diamond
Diamond is a giant covalent structure
Each carbon atom is joined to four other carbon atoms by strong covalent bonds
The carbon atoms have a regular lattice
Silicon dioxide structure
Giant covalent structure
Each silicon atom forms four covalent bonds with four oxygen atoms
This forms a tetrahedral arrangement
Why silicon dioxide can’t conduct electricity
No delocalised electrons in the structure
Why do diamonds not conduct electricity
Has no free electrons or ions
How does graphite conduct electricity and thermal energy
Graphite has delocalised electrons which are free to move between the layers in graphite
Graphene
A single layer of graphite
Properties of graphene that make it useful
It is incredibly light
It is strong
Structure of graphene
Giant covalent structure
A single layer of carbon atoms arranged in a hexagonal lattice
The sheet is 1 atom thick so it’s a two-dimensional substance
How does graphene conduct electricity
Contains delocalised electrons so can conduct electricity through whole structure
Fullerene
Molecules of carbon shaped like closed tubes or hollow balls
Why are fullerenes good for drug delivery in the body
It can be absorbed more easily by the body
How can fullerenes make good lubricants
Fullerenes can reduce friction between two surfaces
Advantage to fullerenes having large surface area
They could make great indrustrial catalysts
Which substances are held together by metallic bonding
Metallic elements and alloys
Which part of metallic bonding produces all the properties of metals
Delocalised electrons
Why are metals solid at room temperature
Electrostatic forces between the positive metal ions and shared negative electrons
Why metals are malleable
The layers of atoms in a metal can slide over each other
Alloys
A mixture of 2 or more metals or a metal and another element
Do different elements have different sized atoms
True
What 3 things do strength of attraction between particles depend on
The material (structure)
Temperature
Pressure
Structure of solids
Strong forces of attraction between particles holding them close together to form regular repeating lattice
Structure of liquids
Weak force of attraction between particles
Randomely arranged
Free to move past each other
Structure of gas
Force of attraction between particles is very weak
Free to move and far apart
Particles in gas travel in straight lines
Name a model for explaining the 3 states of matter
Particles thery
The disgrams of solids liquids gas as circles
What does energy needed for substance to change state depend on
How strong the forces between the particles are
How to know state of a substance
If temperature is below melting point it’ll be solid
If above boiling point it’s a gas
If between a liquid
What happens to surface area as particle decreases in size
Surface area increases
What does very high surface area to volume ratio mean
Surface area is very large compared to the volume
What are nanoparticles used in
Tiny electric circuits for computer chips
Can help make surgical masks
Why should new products containing nanoparticles be tested
To minimise risk as the way they affect the human body isn’t fully understood
