C3- Structure And Bonding Flashcards
What is the particle model?
It assumes that particles are made up of solid spheres with no force operating between them. This is useful to compare the properties of solids liquids and gases.
What are the limitations of the particle model?
The particles that make up substances are atoms, molecules or ions and their interactions can distort the shapes. Atoms are mostly empty space, so real particles are not solid at all
Ionic bonding
When elements react together to form compounds by losing or gaining electrons
What ions so metals form?
Positive (as they lose electrons)
What ions do non-metals form?
Negative (as they gain electrons)
What are oppositely charged ions held together by?
Very strong forces of attraction
The ionic bond between charged particles result in an arrangement of ions called a g____s_____ or g______L______
Giant structure or giant lattice
What ions do Group 4 elements form?
Only tin and lead (bottom if the group) form ions either 4+ or 4-
Why do ionic compounds have high melting points?
Because it takes a lot of energy to break the many strong ionic bonds, operating in all directions, that hold a giant ionic lattice together
When can ionic compounds conduct electricity and why?
When molten or dissolved in water because the ions can become mobile and carry the charge through the liquid
Covalent bonding
When atoms of non-metals share pairs of electrons (each pair is a covalent bond)
Why do structure of simple molecules have low melting and boiling points?
Because they have weak intermolecular forces
Why cant substances made up of simple molecules conduct electricity?
Because their simple molecules have no overall charge, so they can’t carry electrical charge, meaning the substance cannot conduct electricity
Why are model drawings used?
To help us understand bonding, but they each have their limitations in representing reality
Polymers
Made up of small reactive molecules that bond together to form large chains e.g poly(ethene)
Whats a double covalent bond?
When the atoms share 4 electrons in one bond
Whats triple covalent bond?
When the atoms share 6 electrons in one bond
Do all covalently-bonded structures have giant structure?
No just some
Giant covalent structure have ________ melting and boiling points
High
Giant covalent structures are ________ in water
Insoluble
Giant covalent structures are hard/ soft (?) and can/can’t (?)conduct electricity, apart from _________
Hard, can’t, graphite
What can’t giant covalent bonds conduct electricity?
Because they have no free electrons as they are all involved in covalent bonding
Why is Graphite soft and slippery?
Because they are no covalent bonds between its layers of covalently bonded carbon atoms. So the layes can slide over each other
Why can graphite conduct electricity and thermal energy?
Because of its delocalised electrons that can move along its layers (as each carbon atom has 1 free electrons not used for bonding out of the 4 electrons,due to the layers being arranged in hexagons )
The carbon atoms in Diamond have a ________ covalent structure, making it a very ________ substance
Rigid, hard
What are fullerenes?
Carbon also exist as fullerenes and they can form large cage-like structures and tubes based on hexagonal rings of carbon atoms
What are fullerenes started to be used in? (3)
- transport mechanism for drugs to specific site in the body
- catalysts
- reinforcement for composite materials
What is Graphene?
A single layer of graphite and so its just 1 atom thick
Name the properties of graphene
- excellent electrical conductivity
- excellent thermal conductivity
- low density
- strong for its mass
These properties will help it develop in the electronics industry (specially due to its excellent electrical conductivity)
Metallic bonding
Positive,y charged metal ions that are held closely together by delocalised electrons that are free to move throughout the giant lattice
Why can metals be bent and shaped?
Because their layers of atoms (positively charged) in a giant metallic lattice can slide over each other
Whats an alloy?
A mixture of 2 or more elements, at least one of which is a metal
Why are alloys harder than pure metals?
Because the regular layers in pure metals are distorted by atoms of different sizes in an alloy
Why are metals good conductors of thermal and electrical energy?
Because their delocalised electrons can readily flow through the giant metallic lattice and transfer the energy
Whats the state of ionic compounds in room temperature?
All solids
