C2 Flashcards
What is the atomic number
The atomic number is simply the number of protons
What is the mass number and where would you find it
The mass number is the total number of protons and neutrons and it will be the first figure at the top of the symbol
How do I get the neutron?
Subtract the atomic number from the mass number
How are compounds formed?
Compounds are formed when atoms of two or more elements chemically combine together for example carbon dioxide is a compound formed from a chemical reaction between carbon and oxygen
What is the definition of isotopes?
Eiler told a different atomic forms of the same element which had the same number of protons but a different number of neutron
What is ionic bonding?
It is when atoms neutral gain electrons to form charged particles known as Ions they strongly attracted to one another because one of the opposite charges are positive and negative
Explain further on what I mean by ionic compounds have a regular lactase structure
Ionic compounds always have a giant ionic lattice the ions from a closely packed regular lattice arrangement
There are very strong electrostatic forces of attraction between oppositely charged ions in all direction
A single crystal of NaCl (sodium chloride) salt is one giant ionic lattice which is why salt crystals tend to be cuboid in shape the na+ and Cl- ions are held together in a regular lattice
Describe the properties of ionic compounds
They all have high melting points and high boiling point due to the strong attraction between the ion
When ionic compound melt the ions Are free to move and They’ll will carry out an electric current
A dissolves easily in water . The ions separate and free to move in the solution so they will carry out electric current
What group in the periodic table are most likely to form ions
Group 1 -2
Group 6&7
Why are group 1&2 most likely to ions?
Group 1 and group 2 elements are metals and they loose electrons to form positive ions
Why are group 6&7 most likely to form ions
Group 6 and seven elements are non-metals they gain electrons to form negative ions
What is covalent bonding?
It’s sharing electrons in their outer shells with other atoms to involve in having a full outer shell
What are the two types of covalent substances?
Simple molecular substances & giant covalent substances
What is a simple molecular substance ?
The atom form very strong covalent bonds to form small molecules of several atoms
by contrast the forces of attraction between these these monocles are very weak
the results of these feeble intermolecular forces is that the melting points and boiling point are very low because the molecules are easily parted from each other
Why don’t simple molecular substances conduct electricity ?
Because there are no ions so there is no electrical charge
What are macromolecules ?
These are similar to giant ionic structures (lattice) except there are no charged ions
All the atoms bonded to each other by strong covalent bonds this means that they have a very high melting and boiling point
they don’t conduct electricity not even & the main examples of Marcomolecules are diamond and graphite which are both made only from carbon atom and silicon dioxide
Briefly describe the properties of diamond
Each carbon atom forms 4 covalent bonds in a very rigid giant covalent structure this structure makes time in the hardest natural substances so it’s used for drilled tips
What are the properties of graphite?
Each carbon atom only forms 3 covalent bonds this creates layers which are free to slide over each other this is why graphite is soft and slippery there is a weaker Intermolecular forces between the Layers
Why is there a weak intermolecular forces between the layer of graphite
Each carbon atom only forms 3 covalent bonds this creates layers which are free to slide over each other the layers are held together so loosely that they could be rubbed off onto paper ;this is why pencil works
Why is graphite that only non-metal which is a good conductor of heat and electricity?
This is because each carbon atom has one free electron and it’s these free electrons that can.conduct heat and electricity
Describe the properties of an metal
They have free electrons which come from the outer shell of every metal atom in the structure electrons are free to move through the whole structure and so metals are good conductors of heat and electricity
Describe the structure of an metal
The electrons hold the atoms together in a regular structure
There are a strong forces of Electrostatic attraction between the positive metal iron and the negative electrons
The layers of atoms slide over each other allowing metals to be bent and shaped
Why are alloys harder than pure metals ?
Alloys are a mixture of 2 or more metals together
Different elements have different sized atom so when another metal is mixed with a pure metal the new metal atoms disort the layers of metal atoms making it more difficult for them to slide over each other
What is an example of a smart material?
A good example is nitol (half nickel and half titanium) it is a metal alloy but when it’s cool you can bend and twisted like a rubber but if heat it above a certain temperature If goes back to its original shape
What are nanoparticles??
Nano particles are really tiny particles and contain roughly 300 atoms
What do nanoparticles include and explain what they are?
Nano particles include fullerenes these molecules of carbon and carbon atoms are arranged in hexagonal rings
fullerenes can be joined together for two form nano tubes . All those covalent bonds make carbon nanotubes very strong
What are some uses of nanoparticles and how are they being developed?
They have a huge surface area to volume ratio so they could help make new industrial catalyst
Nanoparticles can make sensors to detect one type of molecule and nothing cast for example Pan-Pacific senses are already being used to test water purity
Cosmetic for example suntan cream and deodorant has been made using nanoparticles because the small particles do their job but don’t leave white marks on the skin
Nanotubes can be used to make stronger and lighter building materials
Nanotubes conduct electricity so they can be used in tiny electric circuit for computer chips
What is thermosoftening polymers?
They don’t have cross-linking between their chains The forces between their chains are really easy to overcome so very easy to remould plastic when it cools the polymer hardens into a new shape
What is thermosetting polymers?
They have a cross-link and hold the chain together in a solid structure the polymers doesn’t soften when it’s heated
What up some properties of Thermo softening polymers?
Individual tangled chains of polymers held together by weak intermolecular forces are free to slide over each other
What are some properties of thermosetting polymers?
Some plastics have stronger intermolecular forces between the polymer chains called “cross-linked this holds the chain family together
What could affect the properties of a polymer ?
The starting material
Reaction conditions
Describe the three factors that could reduce the percentage yield of a reaction?
The reaction is reversible so the reactants will never be completely converted to the product because the reaction goes both ways
Some of the products may be lost when it separated from the reaction mixture
Sometimes they can be unexpected reaction happening which uses up the reactants
What are the advantages of using machines to analyse and unknown substances
They are very sensitive and detect even the tiniest amount of substances
They are very fasting tests can be automated
They are very accurate
What is the purpose for gas chromatography?
It can separate out a mixture of a Compound and help you identify the substances present
What are the main stages of gas chromatography?
A gas is used to carry substances for a column packed with a solid material
The substances travel through the tube at different speeds so that they are separated
The time they take to reach the detector is called the retention time it can be used to help identify the substances
The graph draws a Gas chromatograph and the number of peaks shows the number of different compounds in the sample
Give an example of a slow reaction
The rusting of iron
Give an example of a moderate speed reaction?
Is a metal like magnesium reacting with acid to produce a gentle steam of bubbles
Give an example of a really fast reaction
An explosion where it’s all over in the fraction of a second
What four factors: can change the rate of reaction
Temperature
Concentration or pressure for
Catalyst
The surface area of a solid
What formula can be used to measure the rate of a reaction
Rate of reaction = amount of reactant used or amount of product formed / time
What are the different ways rate if reaction can be measured
Precipitation - this is when the product of the reaction is a precipitate which clouds dissolution
Change in mass usually gas given off-measuring the speed of a reaction that produces a glass can be carried out on a mass balance as the gas is released the Mass disappearing is easily measured balanced
The volume of gas given off- this involves the use of a gas syringe to measure the volume of gas given off the more gas given off during a given time the faster the reaction
How does having a higher temperature increase collision?
When the temperature is increasing the particles move quicker and if they are moving quicker they are going to collide more often
How does having an high concentration or pressure increase collision ?
If a solution is made more concentrated it means there are more particles of reactant between the water molecules which make collisions between the important particles more likely.In a gas increasing the pressure means the particles are more squashed up together so there will be more frequent collisions
How does having a larger surface area increases collision ?
If one of the reactants is a solid then breaking it up into smaller pieces will increase the total surface area this means the particles around it in the solution will have more areas to work on so there will be more frequent collision
How does faster collisions increase the rate of reaction?
High-temperature also increases the energy of the collision because it makes all the particles move faster
Reaction only happens if the particles collide with enough energy(activation energy )
At a higher temperature or there will be more particles colliding with enough energy to make the reaction happen
What does activation energy mean?
The minimum amount of energy needed by the particles to react
What is a catalyst?
A catalyst is a substance which speeds up a reaction without being changed or used up in the reaction
How does a catalysts speed up the reaction
A solid catalyst works by giving the reacting particles a surface to stick to this increases the number of successful collision and so speeds up the reaction
What are some advantages of using a industrial catalyst
Catalyst increases the rate of reaction which saves a lot of money
Catalyst will allow a reaction to work at a much lower temperature which is good for sustainable development and save money too
A catalyst can never get used up in the reaction so it could be reused
What are some disadvantages of using a industrial catalyst
They can be very expensive to buy an often needs to be removed from the product and be cleaned
Different reactions is different catalyst so if you make more than one product you will need to buy different catalysts for them
Catalysts can be poisoned by impurities so they can stop working this means you have to keep your reaction mixture of very clean
What is an exothermic reaction?
Is one which transfers energy to the surrounding usually in the form of heat and usually shown by a rise in temperature
Examples of exothermic reactions
Burning fuel also called combustion gives out a lot of heat
Neutralisation reaction so acid + alkali are also exothermic
Oxidation reaction are exothermic e.g. adding sodium to water produces heat
What does endothermic reaction mean
Is one which takes in energy from the surrounding usually in the form of heat are usually shown by a fall in temperature
Examples of endothermic reaction?
Thermal decomposition E.g. heat must be supplied to make calcium carbonate decomposed to make quick lime
Sports injury patsies endothermic reaction they take in heat and the pack becomes very cold
