Studied by 2 peopleWhat are the three types of strong chemical bonds?
Metallic, ionic and covalent
Which particles are involved in metallic bonding?
Atoms which share delocalised electrons
When does metallic bonding occur?
In metallic elements and alloys
What do metal structures consist of?
A giant structure of atoms arranged in a regular pattern
What happens to the electrons in the outer shell of metal atoms?
They are delocalised and so are free to move through the whole structure
What gives rise to strong metallic bonds?
The sharing of delocalised electrons
Which particles are involved in ionic bonding?
Oppositely charged ions
When does ionic bonding occur?
In compounds formed from metals combined with non-metals
What happens to electrons when a metal atom reacts with a non-metal atom?
Electrons in the outer shell of the metal atom are transferred to the outer shell of the non-metal atom
How are positively charged ions formed?
Metal atoms lose electrons
How are negatively charged ions formed?
Non-metal atoms gain electrons
What electronic structure do the ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 have?
The electronic structure of a noble gas (Group 0)
What does the charge on the ions produced by metals in groups 1 and 2 and by non-metals in Groups 6 and 7 relate to?
The group number of the element in the Periodic Table
What type structure does an iconic compound have?
A giant structure of ions. Or Giant ionic lattice
Ionic compounds are held together by ionic Bonding. What is the definition of ionic bonding?
Strong electrostatic forces of attraction between oppositely charged ions
Which direction in the lattice do these forces act in?
All directions
When do atoms form covalent bonds?
When they share pairs of electrons
What strength are covalent bonds between atoms?
Strong
Covalently bonded substances consist of..? (give 3 options)
1)Small molecules (many examples)
2)Very large molecules, such as polymers
3)Giant covalent structures, such as diamond and silicon dioxide
What are the three states of matter?
Solid, liquid and gas
When does melting and freezing take place?
At the melting point
When does boiling and condensing take place?
At the boiling point
What are the limitations of this simple model for the three states of matter? (give 3)
There are no forces, all particles are represented as spheres and the spheres are solid
What does the amount of energy to change state depend on?
The strength of the forces between the particles of the substance
What does the nature of particles in a substance depend on?
The type of bonding and the structure of the substance
What happens to melting and boiling points if the forces between particles become stronger?
They increase
Why do most metals have high melting points?
They are giant structures of atoms that require large amounts of energy to break the strong metallic bonds
Why can pure metals be bent and shaped?
The metal atoms are arranged in layers which can easily slide over each other when a force is applied
What is the problem with pure metals and how is this overcome?
Too soft for many uses-so are made into alloys which are harder
What is an alloy?
A mixture of a metal with small amounts of other substances, usually other metals
Why are alloys harder than pure metals?
The layers of atoms are distorted and cannot slide over each other easily
Why are metals good conductors of electricity?
Delocalised electrons carry electrical charge through the metal
Why are metals good conductors of thermal energy?
Energy is transferred by the delocalised electrons
Why do ionic compounds have high melting and boiling points?
Large amounts of energy needed to break the many strong electrostatic attractions between oppositely charged ions
Why can ionic compounds that are melted or dissolved in water conduct electricity?
The ions are free to move and so charge can flow
Why are substances that consist of small molecules usually a gas or a liquid?
They have relatively low melting and boiling points
When melting and boiling a substance with a simple molecular structure,what needs to be overcome?
Weak forces between the molecules
What happens to the covalent bonds within a molecule when the substance is melted and boiled?
The covalent bonds remain intact
Why do larger molecules have higher melting and boiling points?
The intermolecular forces increase with the size of the molecules
Why do small molecular substances not conduct electricity?
The molecules do not have an overall electric charge
What state do substances wiuth giant covalent structures have at room temperature and why?
Solid because their melting points are very high
What just be overcome in order to melt or boil a substance with a giant covalent structure?
The many strong covalent bonds that link all the atoms in the structure to other atoms
Can you name 3 examples of substances with giant covalent structures?
Diamond and graphite and silicon dioxide
How many bonds does each carbon atom make in diamond?
Four covalent bins with 4 other carbon atoms
What type of structure does diamond have?
Giant Covalent Lattice
State 3 properties of diamond
1)Very hard
2)Very high melting point
3)Does not conduct electricity
Why is diamond very hard?
Atoms are held together in a rigid continuous network held together by strong covalent bonds
Why does diamond have a very high melting point?
Large amounts of energy needed to overcome many strong covalent bonds
Why does diamond not conduct electricity?
Structure doesn't contain delocalised electrons
How many bonds does each carbon atom make in graphite?
3 covalent bonds
What is the structure of graphite?
Layers of hexagonal rings which have no covalent bonds between the layers
In graphite, how many delocalised electrons are there?
One per carbon atom
State 3 properties of graphite
1)Soft
2)Very high melting point
3)Conducts electricity
Why is graphite soft?
Layers of atoms are not bonded together so can easily slide over each other
Why does graphite have a very high melting point?
Large amounts of energy needed to overcome many strong covalent bonds
How does graphite conduct electricity?
The delocalised electrons can move through the structure carrying a charge
How is the structure of graphene related to the structure of graphite?
It is one single layer of graphite - 1 atom thick
State 3 properties of graphene
1)Very thin but extremely strong
2)Good thermal and electrical conductor
3)Semi see-through
Why is graphene very thin but extremely strong?
Only 1 atom thick but a giant covalent structure
Why is graphene a good thermal and electrical conductor?
Delocalised electrons can move through the structure carrying a charge
Why is rgaphene semi see-through?
Only 1 atom thick
What are fullerenes?
Molecules of carbon atoms with hollow shapes
What are the structure of fullerenes based on?
Hexagonal rings of carbon atoms but some contain toings of 6 or 7 carbon atoms
How many bonds does each carbon atom make in fullerenes?
Each carbon atom makes 3 bonds with other carbon atoms
What was the first fullerene to be discovered?
Buckminsterfullerene (C60) which has a spherical shape
What are some uses of fullerene? (3 uses)
1)Drug delivery to specific parts of body or cells
2)As lubricants
3)As catalysts
Why can fullerenes be used as lubricants?
They are ball-shaped so can roll over each other
What are carbon nanotubes?
Cylindrical fullerenes with very high length ot diameter ratio
What do carbon nanotubes properties make them useful for? (3 uses)
1)Nanotechnology
What is a nanometer? (in m)
1x10^-9m
What diameter do (PM2.5) particles have?
Between 100 and 2500nm
What diameter do coarse particles (PM10)have?
Between 1x10^-5m and 2.5x10^-6m
What size particles does dust normally have?
Coarse particles (PM10)
As the size of a cube decreases by a factor of 10, how does the surface area to volume ratio change?
Increases by a factor of 10
Why do nanoparticles have properties different from those for the same materials in bulk?
They have a high surface area to volume rario
How does this affect the quantities of nanoparticles needed to be effective than for materials with normal particle sizes?
Smaller quantities of nanoparticles may be needed
States 5 application s of nanoparticles
Medicine, electronics, cosmetics and sun creams, deodorants and as a catalysts
What is an important area of nanoscience research?
New applications for nanoparticulate materials
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