✅ Flashcards
What is it called when atoms share electrons
Covalent bonding
What is it called when atoms transfer electrons?
Ionic bonding?
What arrangement is formed when ionic bonding occurs?
Giant structure/ giant lattice
Characteristics of ionic compounds
High melting points
Conduct electricity
Characteristics of simple molecules
Weak intermolecular forces
Can’t carry electricity
Why can graphite conduct electricity
Delocalised electrons carry charge
What are fullerenes?
Hollow shapes molecules of carbon
Uses of fullerenes
Transport of drugs
Catalysts
Reinforcement
What is graphene?
I atom thick graphite
What is metallic bonding?
When the negative electrons hold the positive nuclei in position
What is an alloy?
Mixture of two elements, at least one of which is metal
Why can metals bend?
The layers slide over eachother
Why do nano particles have different properties?
Large SA to volume ratio
Uses of nano particles
Sun cream
Glass
Cosmetics
what is it called when a solid changes directly to a gas?
sublimation
what is a compound?
something that contains two or more elements chemically combined
when elecctrons have been gained what is the charge of the ion?
negative
what arrangement do ionic bonds give?
giant lattice
why do lattices have such high boiling points?
the ionic bonds act in all directions on an atom
why will molten or dissolved ionic compounds conduct electricity
ions free to move
What are the three states of matter
Solid
Liquid
Gas
Characteristics of particles in solid
Packed closely together
Vibrate in fixed positions
Characteristic of liquid
Close together but can slide around
Characteristics of gas
Lots of empty space of particles to move around
What energy changes happen when something melts or boils?
Energy is transferred to the substance
Limitations of the simple particle model
Atoms aren’t all solid spheres with no forces between them
Why do different substances have different melting points
Depends on the strength of the bonds between them
What is covalent
When two atoms share electrons
What is ionic bonding?
When atoms transfer electrons to each other and become ions
How do ionic compounds stay together.
The forces of attraction between the oppositely charges ions
What is formed with ionic bonds
A giant structure or giant lattice
Why do ionic compounds have such high melting and boiling points?
The strong electrostatic forces of attraction
How to work out the charge of an ionic compound
Look at the charges of the ions
Th overall charge must be 0, so there must be enough of each to cancel out
Why will ionic compounds only conduct electricity when dissolved or molten?
The ions become mobile and can carry the charge through the liquid
What are covalent bonds?
The strong bonds between atoms that are sharing electrons
What is a macromolecule
A giant covalent structure
Ho do a shared pair of electrons bond the atoms together?
The positive nuclei are attracted to the negative pair of electrons
What are the three ways of representing covalent bonding
Dot and cross Displayed formula (single lines show bonds) The 3D model
Why is it easy to break apart a simple molecular compound (why does it have a lot m and b point)
Weak intermolecular forces
Why don’t molecular compounds conduct electricity?
They aren’t charged so there are no free electrons
What is a polymer?
A long chain made up of smaller molecules
Why does diamond have such a high melting point
Very strong intermolecular forces (bonds to four different atoms)
What are intermolecular forces?
The forces between the covalently bonded molecules
Why do macromolecules have such a high melting point
All the atoms are bonded to eachother by strong covalent bonds
Why can layers in graphite slide off eachother
Weak intermolecular forces
What are delocalised electrons
Spare electrons that don’t belong to an atoms so can move through out graphite
Why does graphite conduct electricity
Delocalised electrons
What is a fullerene?
A large hollow cage made of carbon
How many carbon atoms are in a fullerene
60
What are carbon nanotubes
Cylindrical fullerenes
What is graphene?
A single layer of carbon atoms
Three uses of fullerenes
Can ‘cage’ other molecules
Deliver drugs
Catalyst
What type of bonding occurs in metals?
Metallic bonding
How are metallic bonds so strong?
The positive metal ions are attracted to the negative delocalised electrons
What is an alloy?
A mixture of two elements, at least one of which is a metal
Why are metals solid at room temperature?
Strong electrostatic bonds
Why are metals good conductors of electricity and heat
Delocalised electrons carry charge and energy
Why are metals malleable
Layers of atoms can slide over eachother
Why are alloys harder than normal metals
The different sizes atoms mean it’s harder for the layers to slide over eachother
What is a nanoparticle?
A very small particle
What is important about nanoparticles
Large surface area to volume ratio
What is the size range for a nanoparticle
Between 10-9 and 10-7 metres
Uses of nanoparticle
Catalysts
Nanomedicine (magic bullet)
Suncreans
Cosmetics
Risks of nanoparticle
Large surface area = flammable
Breathing them in could damage bloodstream
Affecting environment
What are nanowires
Very small wires used in electronic circuit
What are silve nanoparticles used for
Inhibit growth of microorganism
Textiles
Sanitation (silver ions protect against bacteria)
How are nanocages used to deliver drugs
Can get into the leaky walls of tumours and carry drugs at same time
