Year 11 Mock Flashcards
What is covalent bonding
Non metals combined together by sharing electrons. The shared pair of electrons holds the 2 atoms together.
Why are covalent bonds strong
there is a strong electrostatic force of attraction between the positive nuclei of the atoms and the negative electrons in each shared pair
What do we use to show covalent bonds
dot and cross diagrams
What are simple molecular substances
Formed by covalent bonds with simple molecular structures such as CO2 and H20.
Properties of simple molecular structures
Held together by strong covalent bonds
Force of attraction between the molecules are weak
Melting and boiling points are very low because the molecules are easily parted from each other.
Gases or liquids at room temperature and don’t conduct electricity because they don’t have free electrons or ions.
Properties of Giant covalent structures
Atoms are bonded to each other by strong covalent bonds
Very high melting and boiling points
Don’t conduct electricity
What are giant covalent bonds
Similar to a giant ionic lattice except that there are NO charged ions
Properties of Diamond
each carbon atoms forms 4 covalent bonds in a very rigid giant covalent structure.
Hard, takes a lot of energy to break
High melting and boiling point
Doesn’t conduct electricity because it has no free electrons.
Properties of Graphite
Black, opaque and shiny
Each carbon atom forms 3 covalent bonds, creating sheets of carbon atoms which are free to slide over eachother.
High melting point, need loads of energy to break.
Conducts electricity
How does graphite conduct electricity
Only 3 out of 4 of carbons 4 outer electrons are used in bonds, there are lots of delocalised electrons that can move = electricity.
Uses of Graphite
a lubricating material and electrodes as the layers are held together weakly so they are slippery and can be rubbed off on paper= pencil.
Uses of diamonds
cutting tools
jewelry
What are fullerenes
Another form of carbon , large molecules shaped like hollow balls or tubes, atoms arranged in rings and have free electrons so can conduct electricity
What is Graphene
A single sheet of graphite, strong covalent bonds, free electrons can conduct electricity better than graphite
What is ionic bonding
Form between positive and negative ions, which attract each other and bind together by gaining or losing electrons to form ionic compounds (full outer shell) eg- Sodium.
What happens to metals and non metals in ionic bonding
Metals can lose electrons to form a positively charges ion and the non metal can gain electrons to form a negatively charged ion.
What are oppositely charged ions strongly attracted to one another by
electrostatic force of attraction
How do you find the formula of an ionic compound
balance the positive and negative charges
What do we use to show ionic bonding
Dot and Cross diagram
What happens in the ionic bond of sodium chloride (NaCl)
Sodium atom has a electronic configuration of 2,8,1 therefore needs to lose its outer electron to have a full shell. The Chlorine atom has an electronic configuration of 2,8,7 therefore needs to gain an electron to have a full outer shell. Sodium gives up its outer electron and Chlorine gains it. This gives Na a + charge and Cl a - charge.
What structure do Ionic compounds have
Giant ionic lattice structure, ions form a closely packed regular lattice. There are very strong electrostatic forces of attraction between oppositely charged ions, in all directions.
What are the properties of Ionic compounds
High melting and boiling points due to strong attraction between ions, takes a large amount of energy to overcome it.
Don’t conduct electricity because the ions are fixed in place and can’t move
DISSOLVE EASILY IN WATER.
What happens when ions dissolve in water or become molten
The ions separate and are all free to move in the solution, so they’ll carry an electric current.
What structure do metals have
Crystal
Properties of the structure of metals
Outer electrons are free
Atoms become positive ions in a sea of delocalised electrons
What is metallic bonding
The electrostatic attraction between these ions and electrons in metals
Which side of the periodic table are metals found
left hand side
Properties of METALS THEMSELVES and their abilities
High melting and boiling points because of strong metallic bonds
High densities
High tensile shape- Hard to break
Malleable (can be hammered into different shapes)
Conduct head and electricity through free electrons
What happens when metals react with oxygen and when they dissolve in water
Form metal oxides
Most metal oxides are solid at room temperature and form basic solutions when you dissolve them in water
What are alloys
Changing a metals properties by mixing it with other elements (metals or non metals) to change their structure to make them more; strong, malleable or more corrosion resistant
Properties of non metals
Low melting and boiling point, when solid they tend to be weak and brittle. Low density and dont conduct electricity.
Gas or solid at RT
What is neutralization
A reaction in which acidity or alkalinity is removed
What does a A neutralization involving an acid and a base (or alkali) always produce?
Salt and water
What do all acids contain
Hydrogen H+ ions, the greater the concentration of these the lower the pH.
What base forms if hydrochloric acid is used
Chloride
What base forms if Nitric acid is used
Nitrate
What base forms if Sulfuric acid is used
Sulfate
What base forms if phosphoric acid is used
Phosphate
If the acid hyrdochloric acid is used with the base copper oxide, what salt will be formed?
copper chloride + water
Test for hydrogen
A lighted wooden splint that makes a squeaky pop
Test for Oxygen
A glowing wooden splint relights in a test tube of O
Test for Carbon Dioxide
Lighted splint goes out or Bubble test through limewater (calcium hydroxide solution) CO2 will turn lime water a cloudy white.
Test for Ammonia
Sharp, choking smell. Turns damp red litmus paper blue
Test for chlorine
Sharp, choking smell. Turns damp blue litmus paper red and then bleaches it white
What do Titrations allow us to do
Used to find out concentrations, Find out exactly how much acid is needed to neutralize a given quantity of alkali (or vice versa)
Describe the experiment of a titration
Measure out a set volume of alkali into a flask with a pipette. Add drops of indicator.
Fill a burette with a standard solution (a known concentration of acid)
Use the burette to add the acid to the alkali bit at a time. Swirl the flask regularly. Slowly (drop at a time) when the alkali’s almost neutralized.
The indicator changes colour when all the alkali is neutralized (end point).
Record the volume of acid used to neutralize the alkali (titrate)
Repeat process to get concordant results (WITHIN 0.2)
Why can’t you use a universal indicator
It changed colour gradually and you need a single colour change
What should you remember to do first in a titration
Do a rough one first to rinse out the equipment.
Indicators used and what colours they should turn
Phenolphthalein- colourless in acids and pink in alkali
Methyl orange- yellow/peach in alkali but red in acids
what are the 2 techniques for the Production of ethanol
Fermentation of glucose and hydration of ethene
Describe Fermentation
Sugars from plant material is converted into ethanol and CO2. The enzymes found in single celled fungi YEAST are the natural catalysts for this process. Temperatures required are 30-40*, with 1 atmosphere pressure and rate is slow. Thank
What needs to happen after fermentation process
To purify it, it needs to be fractionally distilled to concentrate the ethanol.
Describe hydration of ethene
Reacting ethene from crude oils with steam, a catalyst of phosphoric acid is used to ensure a fast reaction. Non renewable, works at temperatures of 300* and 65 atmospheric pressure, highly pure product
How are soluble salts made
Soluble salts can be made from acids by reacting them with solid insoluble substances, such as metals, metal oxides, hydroxides or carbonates.
Practical for making insoluble salts
Using precipitation reactions where you pick 2 soluble salts, they react and you get your insoluble salt eg- mix lead nitrate and sodium chloride to make lead chloride
What is atom economy
A way to measure the atoms wasted to make a chemical. The higher atom economy the “greener” the process.
what does 100% atom economy mean
all the atoms in the reactants have been converted to the desired product.
How to calculate atom economy
Mr of desired products∕sum of Mr of all products × 100
What does poly(ethene) show
Simple polymers consist of large molecules containing chains of carbon atoms
limitations of particular representations and
models, to include dot and cross, ball and stick models and
two- and three-dimensional representations
Mainly applies well to the smaller class of solids composed of group 1 and 2 elements with the highly electronegative elements such as halogens- can't show large molecules In covalent molecular, the dot-cross diagrams don’t show the relative attraction of shared electrons due to electronegativity
What is the molar volume of any gas at room temperature and pressure
24dm3 or 24000cm3
What do chemical cells do
produce a voltage until one of the reactants is used up
What is used in a hydrogen-oxygen fuel cell to produce a voltage
hydrogen and oxygen are used to produce a voltage and water is the only product
Evaluate the strengths and weaknesses of fuel cells for given uses
Environmental benefit – only water produced
Overall has a greater efficiency
Rechargeable
Expensive
Difficulties of transportation and storage of hydrogen
How did Mendeleev arrange his periodic table
In order of relative atomic mass
What are the steps for finding percentage yield
1- Ar Mr find number of moles
2- Use balance equation DP TR
3-Find mass —> KG
4- Percentage yield equation
= actual yield/ theoretical yield * 100
How to convert gdm3 to moldm3
Divide conc in gdm3 by MR of solute
Steps for finding concentration from titrations
Find moles of acid or alkali (opposite from question)
Use equation to find ratios- Multiply to make same if not already
Use formula triangle to find conc of acid or alkali (what question asks)
How to find number of protons, neutrons and electrons
Protons and electrons are the same and are the bottom number= atomic number
Neutrons and protons are in the top number= mass number
Where does oxidation occur
At the anode
Where does reduction occur
At the cathode
How do we know what group ma elements in
The amount of electrons it has on its outer she
P
How do we know what period an elements in
How many shells of electrons it has
Explain the practical for making soluble salts
Measure required volume of acid with measuring cylinder and add the weighed solid (insoluble metal, oxide, hydroxide or carbonate) in small portions with stirring.
Safety goggles required- the mixture may be heated to speed up the reaction. When no more of the solid dissolves, it means all the acid is neaturalised and there should be a little excess solid. Filter the solution to remove the excess solid into evaporating fish. On filtration, only a solution of the salt is left. Then hot concentrated solution is left to cool and crystallise. After crystallisation, you collect and dry the crystals with a filter paper. If the solution is heated, the solvent will evaporate faster. Heating a solution until all the solvent has evaporated is known as heating to dryness
What are soluble
All nitrates All common sodium, potassium and ammonium salts Most chlorides Most sulfates Sodium potassium and ammonium carbonates Sodium potassium and ammonium hydroxides
What are insoluble
Silver chloride and lead chloride
Lead sulfate, barium sulfate and calcium sulfates
Most carbonates
Most hydroxides
Practical for making insoluble salts
Mix together solutions of soluble salts
Insoluble salt will form a precipitate in the solution
Filter off the precipitate and wash several times with pure water
Dry precipitate in an oven
What’s the definition of an alkali
Example of a soluble base
What is a base
Any substance that reacts with an acid to form salt and water only
What’s the general equation for a reaction between acids and metal oxides
Acid + metal oxide —salt +water
What’s the general equation for a reaction between acids and metal hydroxides
Acid + metal hydroxide — salt + water
What’s the general equation for a reaction between acids and metal carbonates
Acid + metal carbonate — salt+ water + carbonate
