C1- Bonding, Structure and Properties of Matter Flashcards
What is an ion?
Charged particles that can be single or groups of atoms
How do ions form?
When atoms lose or gain electrons to try and get a full outer shell
How do positive ions form?
When metals form ions they lose electrons from their outer shell
How do negative ions form?
When non metals from ions they gain electrons into their outer shell
What is the charge of the ion the same as?
The number of electrons lost or gained, if 2 lost, the charge is +2
Which groups are most likely to form ions?
1&2
6&7
What are positive ions called?
Cations
What are negative ions called?
Anions
List the groups and their ion charge
G1 = 1+
G2 = 2+
G3 = 3+
G5 = 3-
G6 = 2-
G7 = 1-
What are the three types of bonding?
Ionic
Covalent
Metallic
What is ionic bonding (simple)?
Transfer of electrons
What is ionic bonding (detailed)?
When a metal and a non metal react together, the metal atom loses electrons to form a positively charged ion and the non metal gains these electrons to form a negatively charged ion. These oppositely charged ions are strongly attracted to one another by electrostatic forces. This attraction is called an ionic bond.
Dot cross diagrams to show how ionic compounds are formed
In book
What are the limits of dot cross diagrams?
They don’t show the structure of the compound, the size of the ions, or how they’re arranged
What is the structure of an ionic compound called?
A regular lattice structure
A giant ionic lattice
Describe a regular lattice structure
Ions form a closely packed regular lattice arrangement and there are very strong electrostatic forces of attraction between oppositely charged ions in all directions in the lattice.
Structure of sodium chloride
In book
Do ionic compounds have high or low melting and boiling points and why?
High melting and boiling points due to the many strong bonds between ions. It takes a lot of energy to overcome the attraction.
In what state of matter can ionic compounds conduct electricity and what state can’t they?
When they’re solid the ions are held in place so the compounds can’t conduct electricity.
When ionic compounds melt the ions are free to move and they’ll carry electric charge.
Does ionic bonding occur in metals, non metals or both?
Both
What happens to some ionic compounds in water?
Some dissolve in water. The ions separate and are free to move in the solution so they’ll carry electrical charge.
How do you find the empirical formula of an ionic compound?
From a diagram of the compound. If dot cross, count up how many atoms there are of each element.
If 3 D diagram of ionic lattice, use it to work out what ions are in the compound, balance the ion charges so the overall compound charge is zero.
What is covalent bonding (simple)?
Sharing electrons
What is covalent bonding (detail)?
When non metal atoms bond together they share pairs of electrons to make covalent bonds. The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces making covalent bonds very strong. Atoms only share electrons in their outer shells. Each singled covalent bond provides one extra shared electron for each atom. Each atom involved generally makes enough covalent bonds to fill up its outer shell.
Does covalent bonding occur in metals, non metals, or both?
Compounds of non metals
Non metal elements
How can you draw covalent bonds?
Dot cross in books
What are simple molecular substances?
Structures made up of molecules containing a few atoms joined together by covalent bonds
Give 7 examples of simple molecular substances
Hydrogen
Chlorine
Oxygen
Nitrogen
Methane
Water
Hydrogen Chloride
What bonds do substances with simple molecular substances usually have?
Covalent bonds
The atoms within the molecules are held together by very ____ ______ bonds. By contrast the forces of attraction between the molecules are very ____
strong
covalent
weak
What are the melting and boiling points of simple molecular substances like?
Very low due to weak inter molecular forces
What states are most molecular substances at room temperature?
Gases
Liquids
As molecules get ____ the strength of the inter molecular forces _____ so ____ energy is needed to break them and the melting and boiling points ____
Bigger
Increases
More
Increase
Do molecular compounds conduct electricity and why?
No because they aren’t charged so there are no free electrons or ions
What are polymers?
Lots of small units are linked together to form a long molecule that has repeating sections. All the atoms in a polymer are joined by strong covalent bonds.
How do you draw a polymer?
Draw the shortest repeating section called the repeating unit, shown in book
How do you find the molecular formula of a polymer?
Write down the mf of the repeating unit in brackets and put an n outside
What are the intermolecular forces of a polymer molecule like?
Larger than between simple covalent molecules so more energy is needed to break them
What state are most polymers at room temperature?
Solids
What is the boiling point of a polymer like?
Lower that ionic or giant molecular compounds as the im forces are still weaker than ionic or covalent bonds
What are giant covalent structures (one word)?
Macromolecules
What are three features of a giant covalent structure?
All the atoms are bonded to each other by strong covalent bonds
They have very high melting and boiling points
They don’t contain charged particles so don’t conduct electricity
What are the 3 main examples of giant covalent structures you need to know and what are they made of?
Diamond and graphite made of only carbon atoms
Silicon dioxide (called silica) made of silicon and oxygen
What is an allotrope?
A different structural form of the same element in the same physical state
What are 4 allotropes of carbon?
Diamond
Graphite
Graphene
Fullerenes
Describe structure and features of diamond
Giant covalent structure made up of carbon atoms that each form four covalent bonds meaning diamond is very hard
Strong covalent bonds that take a lot of energy to break giving diamond a very high melting point
It doesn’t conduct electricity because it has no free electrons or ions
Tetrihidal shape
Describe structure and features of graphite
Each carbon atom only forms three covalent bonds creating sheets of carbon atoms arranged in hexagons
There aren’t any covalent bonds between the layers they’re only held together weakly so they’re free to move over each other this makes graphite soft and slippery so it is a good lubricating material
Graphite has a high melting point the covalent bonds in the layers need loads of energy to break
Only three out of each carbons four outer electrons are used in bonds so each carbon atom has one electron that is delocalised so graphite conducts electricity and thermal energy
Describe the structure and features of graphene
It is sheet of carbon atoms joined together in hexagons
The sheet is one atom thick making it a 2 dimensional substances
It is very strong and light
Contains delocalised electrons so can conduct electricity throughout the whole structure
What can graphene be used for?
Electronics and composite materials due to its light weight and good electricity conduction
Describe the structure and features of fullerenes
They are molecules of carbon shaped like closed tubes or hollow balls
They’re mainly made up of carbon atoms arranged in hexagons but can also contain pentagons or heptagons
What could fullerenes be used for and why?
To cage other molecules, the structure forms around another atom or molecule which is then trapped inside, this could be used to deliver a drug into the body.
Huge surface area which could help make great industrial catalysts, individual catalyst molecules could be attached to the fullerenes. Fullerenes also make great lubricants.
What are nanotubes formed by fullerenes?
Tiny carbon cylinders
Ratio between length and diameter is very high
Can conduct both electricity and thermal energy
High tensile strength so they don’t break when stretched
Nanotechnology
Give 2 broad uses of nanotechnology
Electronics or to strengthen materials without adding much weight
What was the first fullerene discovered and what was its shape and formula?
Buckminsterfullerene
Molecular formula C60
Forms a hollow sphere
What is metallic bonding?
Metals consist of a giant structure
The electrons in the outer shell are delocalised, there are strong forces of electrostatic attraction between the positive metal ions and the shared negative electrons
These forces of attraction hold the atoms together in a regular structure and are known as metallic bonding.
What are 2 substances that are held together by metallic bonding?
Metallic elements and alloys
What do the delocalised electrons in metallic bonding produce?
All the properties of metals
What state are metals at room temperature?
Solid
What are the melting and boiling points of metals like and why?
High due to strong electrostatic forces between atoms and strong sea of delocalised electrons
How good are metals at conducting and why?
They are good conductors of electricity and heat as the delocalised electrons carry electric charge and thermal heat energy through the whole structure
Most metals are m_____
Malleable
Why are metals malleable?
The layers of atoms in a metal can slide over eachother
What does malleable mean?
They can be bent, hammered, or rolled into flat sheets
Pure metals are ___
Alloys are ____
Hard/soft
Soft
Hard
What is an alloy?
A mixture of two or more metals or a metal and another element
Why are alloys harder than pure metals?
Different elements have different sized atoms so when another element is mixed with a pure metal, the new atoms will distort the layers of metal atoms making it more difficult for them to slide over each other
Particle theory model of solids explained
- In solids there are strong forces of attraction between particles which holds them close together in fixed positions to form a very regular lattice arrangement
- The particles don’t move from their positions so all solids keep a definite shape and volume and don’t flow like liquids
- The particles vibrate about their positions, the hotter the solid becomes the more they vibrate causing solids to expand slightly when heated
Particle theory model of liquids explained
- In liquids there is a weak force of attraction between the particles, they’re randomly arranged and free to move past each other but stick closely together
- Liquids have a definite volume but don’t keep a definite shape and will flow to the bottom of a container
- The particles are constantly moving with random motion, the hotter the liquid gets the faster they move, this causes liquids to expand slightly when heated
Particle theory model of gases explained
- In gases the force of attraction between the particles is very weak, they’re free to move and are far apart, the particles in gases travel in straight lines
- Gases don’t keep a definite shape of volume and will always fill any container
- The particles move constantly with random motion, the hotter the gas gets, the faster they move, gases either expand when heated or their pressure increases
What are the negatives of particle theory models?
Particles aren’t actually solid, inelastic, spheres, they are atoms, ions or molecules
The model doesn’t show the forces between particles so there is no way of knowing how strong they are
What are the state symbols for solid, liquid, gas and aqueous?
(s)
(l)
(g)
(aq)
What does aqueous mean?
Dissolved in water
Heating ____ bonds and cooling _____ bonds
Breaks
Forms
How do you predict a substances state at a certain temperature?
If the temperatures below the melting point of the substance, it will be solid. If it’s above the boiling point, it will be gas. If it’s between the two points then it is a liquid
What is the diameter of a nano particle?
Between 1nm (1 X 10^-9) and 100nm (1 X 10^-7)
Nanoparticles have a large _____ ____ ____ _____ ratio
Surface area to volume
Surface area to volume ratio =
Surface area / volume
As particles ____ in size, the size of their surface area ____ in relation to their volume
Decrease
Increases
Give 5 uses of nano particles
- Catalysts
- Nano medicine
- Computer chip circuits
- Antibacterials (Surgical masks, wound dressings, deodorant)
- Cosmetics
Why are nano particles good catalysts?
High surface area to volume ratio
Why could nano particles be used in medicine?
They are tiny and absorbed easily so could take medicine directly to the cells
Why could nano particles be used in computer chips?
Some conduct electricity well so would be useful in tiny circuits
Why could nano particles be used for antibacterial properties?
Silver nano particles have these properties so could be added to polymer fibres and used to create such objects
Why could nano particles be used in cosmetics?
Used to improve moisturisers without making them oily
What are 3 problems with nano particles?
- The way they affect the body is not understood
- We do not know the long term health impacts
- They should be clearly labelled due to these
What are 2 positives and 2 negatives of nano particles used in sun cream?
- Better at UV protection than traditional creams
- Better skin coverage
- Might damage body and cells
- Could damage enviroment
