Bonding Structure Flashcards
What is ionic bonding?
When particles are oppositely charged ions
What is covalent bonding?
When particles are atoms which share pairs of electrons
What is metallic bonding?
When particles are atoms which share delocalised electrons
What are ions?
Charged particles
Why do atoms lose or gain electrons?
To get a full outer shell
Why do atoms want a full outer shell?
To have a stable electronic structure
How do metals form ions?
By losing electrons
What do metals form when they lose electrons?
A positive ion
How do non-metals form ions?
By gaining electrons
What do non-metals form when they gain electrons?
A negative ion
What are cations?
Positive ions
What are anions?
Negative ions
What is ionic bonding with?
A metal and non-metal
How are oppositely charged ions attracted to each other?
By electrostatic forces
What structure do ionic compounds have?
Regular giant lattice structure
What is a regular giant lattice structure?
Ions closely packed in a regular lattice arrangement with strong electrostatic forces of attraction between oppositely charged ions, in all directions in the lattice
What are properties of ionic compounds?
High melting + boiling point Can't conduct electricity when solid Can carry current when molten or dissolved Soluble Brittle
Why do ionic compounds have a high melting and boiling points?
Because there are many strong bonds between ions and a lot of energy is needed to overcome this attraction
Why can’t ionic compounds conduct electricity when solid?
Ions are held in place
Why can ionic compounds conduct electricity when molten or dissolved?
Ions are free to move
Why are ionic compounds brittle?
When a force is applied, the pattern is disrupted so like ions are forced together. Like charges repel and the repulsion breaks the lattice structure
What happens to the ions when dissolved?
They separate and are free to move in the solution
What is covalent bonding with?
Non-metals
What do non-metals do to make covalent bonds?
Share pairs of electrons
Why are covalent bonds strong?
The positively charges nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces
Which electrons do atoms share?
Electrons in their outer shells (highest energy level)
What are simple molecular substance made up of?
Molecules containing a few atoms joined together by covalent bonds
Are the forces of attraction between simple molecular substances strong or weak?
Weak
Why are melting and boiling points of simple molecular substances low?
The molecules are easily parted from each other because of weak intermolecular forces
What happens as molecules get bigger?
The strength of the intermolecular forces increases, so more energy is needed to break them. This means that the melting and boiling point increases
Why don’t molecular compounds conduct electricity?
Because they aren’t charged - have no free electrons or ions
What are polymers?
Lots of small units linked together to form long molecules that has repeating section
How are atoms in a polymer joined together?
By covalent bonds
What is the difference between intermolecular forces between polymer molecules and simple covalent molecules? What does this mean?
The intermolecular forces between polymer molecules are bigger, so more energy is needed to break them - higher melting and boiling points
Are the intermolecular forces between polymer molecules stronger or weaker than ionic or covalent bonds?
Weaker , so lower boiling points than ionic or giant molecular compounds
How are atoms in giant covalent structures bonded?
All the atoms are bonded to each other by strong covalent bonds
Why do giant covalent structures have high melting and boiling points?
Because lots of energy is needed to break the strong covalent bonds between the atoms
Why don’t giant covalent structures conduct electricity?
Because they don’t contain charged particles
How many covalent bonds does each carbon atom form in diamonds?
4
Why are diamonds hard?
They have a very rigid giant covalent structure
What are 2 properties of diamond?
Hard
High melting point
Don’t conduct electricity
What has a similar structure to diamond?
Silicon dioxide
How many covalent bonds does each carbon atom form in graphite?
3
How many delocalised electrons does each carbon atoms have in graphite
1 free electron
What is the forces that join sheets of atoms (in graphite) like?
They are joined together by weak forces
Why is graphite soft and slippery?
Because the layers are free to slide over each other because the forces between the layers are week
What is a use of graphite due to being slippery?
Lubricant material
Why does graphite conduct electricity?
Because the extra electrons form a sea of delocalised electrons between the layers which can carry a charge through the structure
What is graphene?
One layer of graphite - sheet of carbon atoms joined together in hexagons, only one atom thick
Why is graphene very strong?
Because of the network of covalent bonds
What is a benefit of graphene being light?
It can be added to composite materials to improve their strength without adding to much weight
Can graphene conduct electricity? If so why?
Yes. Because it contains delocalised electrons that can carry a charge through the whole structure
What are fullerenes?
Molecules of carbon shaped like closed tubes or hollow balls
What can fullerenes be used for?
They can be used to ‘cage’ other molecules. The fullerene structure forms around another atom or molecules, which is trapped inside. This can be used to deliver a drug into the body
How does fullerenes having a large surface area benefit?
They could help make great industrial catalysts - individual catalyst molecules can be attached to fullerenes
Are fullerenes good lubricants?
Yes
What can fullerenes form?
Nanotubes
What are nanotubes?
Tiny carbon cylinders
What can nanotubes conduct?
Electricity and thermal energy (heat)
Do nanotubes have a high tensile strength?
Yes - they don’t break when stretched
What are metals like (structure wise)?
They have a giant structure where the atoms are held together by strong bonds in regular structures
What are the electrons in the other shell of a metal atom?
They are delocalised
There are strong forces of __________ _________ between the _____ metal ions and shared _____ electrons
Electrostatic attraction
Positive
Negative
What produces all the properties of metals?
The delocalised electrons in the metallic bonds
Why do metals have a high melting and boiling point?
Because a lot of energy is needed to break the strong electrostatic forces between the metal atoms and delocalised sea of electrons
Why are metals good conductors of electricity and heat?
Because the delocalise electrons carry electrical current and thermal energy (heat) through the whole structure
Why are metals malleable?
Because metals have a regular structure and the layers can slide over each other
Why can metals be drawn into wires easily?
Because they are malleable
What is an alloy?
A mixture of 2 or more metals, or a metal and non-metal
Why use alloys?
Pure metals are often too soft when pure. Alloys are harder and therefore more useful
How are alloys harder than pure metals?
Alloys are harder because when another element is mixed with a pure metal, the new atoms will distort the layers of metal atoms (different elements have different sizes), making it difficult for the layers to slide over each other
Why are metals good conductors of electricity and heat?
The delocalised electrons carry current and thermal energy throughout the whole structure
What does the state of something at a certain temperature depend on?
How strong the forces of attraction are between the particles of the material
What does the strength of forces (state) depend on?
The temperature
The pressure
The material
What are the forces of attraction in solids like?
Strong forces
What are the forces of attraction in liquids like?
Weak forces
What are the forces of attraction in gases like?
Very weak, almost no forces
How are solids arranged?
In fixed positions to form a very regular lattice arrangement
How are liquids arranged?
Randomly, free to move past each other but close together
How are gases arranged?
Free to move and far apart
Shape and volume of solids:
Definite - doesn’t move from their positions
Shape and volume of liquids:
Definite volume but not shape - flow to fill the bottom of the container
Shape and volume of gases:
No definite shape or volume - will fill any container
Motion of solids:
What happens when heated?
The particles vibrate about their positions
The hotter the solid, the more they vibrate
Motion of liquids:
What happens when heated?
The particles constantly move with random motions
The hotter the liquid gets, the faster they move as liquids expand slightly when heated
Motion of gases:
What happens when heated?
The particles constantly move with random motion
The hotter the gas gets, the faster they move. Either expand when heated, or pressure increases
Solid –> Liquid?
Melting
Liquid –> Gas?
Boiling
Gas –> Liquid?
Condensing
Liquid –> Solid?
Freezing
What happens to particles when a solid is melting?
The particles gain more energy when heated
Particles vibrate more
Weaken forces that holds the solid together
At the melting point, the particles have enough energy to break free from positions
What happens to particles when a liquid is boiling?
The particles get more energy
Particles move faster
Breaks the bonds holding the liquid together
At the melting point, the particles have enough energy to break all their bonds
What happens to particles when a gas is condensing?
The particles don’t have enough energy to overcome the forces of attraction
Bonds form between the particles
At boiling point, enough bonds are formed to make the gas a liquid
What happens to particles when a liquid is freezing?
The particles have less energy, move around less
The particles don’t have enough energy to overcome the forces of attraction
More bonds form between the particles
At melting point, so many have bonds formed between the particles that they are now held in place
What are the diameters of nanoparticles?
1nm to 100nm
As particles ________ is size, the size of their surface area _________ in relation to their volume, causing the surface are to volume ratio to ________
Decrease
Increases
Increase
Nanoparticles have a ___ _____ SA to volume ratio
Very high
Uses of Nanoparticles:
To make a new catalyst
Nanomedicine
In electrical circuits - some conduct electricity
Add to polymer fibres used to make surgical masks and wound dressing - some have antibacterial properties
Cosmetics
How could nanoparticles be used in medicine?
The tiny particles are absorbed more easily by the body than most particles - they could deliver drugs right into the cells where they are needed
What is the problem with nonoparticles?
We don’t fully understand the way they affect the body
We don’t know the long term impacts on health etc
