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What are the 3 states of matter?
Solid 2. Liquid 3. Gas
How are covalent bonds formed?
When 2 non-metals share a pair of electrons
Why does a chemical cell eventually stop producing a voltage?
-It is an exothermic reaction and energy is transferred by electricity
-When a reactant is used up, it goes 'flat'
What are some compounds found in fertilisers?
-Nitrogen - NH₄⁺
-Phosphorus PO₄³⁻
-Potassium - dissolve in water to form K⁺ ions
What is the theoretical yield of a reaction?
The maximum amount of a product that can be formed from a reaction
How do you calculate the relative formula mass (Mr) from the relative atomic masses (Ar)?
Ar of all elements added together
What is the symbol for corrosive?
What are some examples of common simple molecular covalent compounds?
-Methane CH4
-Water H2O
-Hydrogen Flourine HF
-Nitrogen Oxide NO2
What is an elctrolyte?
An ionic substance with freely moving ions (molten or in solution)
How are cations formed?
When electrons are lost
What happens in a reversible reaction?
The reaction can proceed both forwards and backwards
What is the common reaction of metal with water?
metal + water → metal hydroxide + hydrogen
How did Mendeleev arrange elements in a periodic table?
By their properties and atomic mass
Where are transition metals positioned in the periodic table?
The middle
What is the difference between a pure substance and a mixture?
A pure substance is only made up of 1 substance (element or compound) that is chemically bonded.
A mixture is made up of elements and compounds that do not react with each other and can be separated with physical processes.
How have Dalton's ideas about atoms changed?
-Dalton thought that atoms were solid spheres that made up all matter and couldn't be created or destroyed. They were the smallest particle.
-JJ Thompson discovered the electron in 1904, came up with the 'plum pudding' model-the atom was a solid positively charged sphere with negative electrons placed inside it
-Rutherford did alpha scattering experiment in 1911. Fired alpha particles through thin gold foil and discovered atoms have a positively charged nucleus and electrons circle on orbits around it
How are anions formed?
Electrons are gained
What is a chemical cell made up of?
2 metals dipped in their salt solution
A 'salt bridge' to allow ions to pass from one to another
Voltage produced between metals
Current flows when connected to an external circuit
How is ammonium nitrate made using ammonia from the Haber process?
N₂+3H₂ ⇌ 2NH₃
-Pressure of 200 atmospheres
-Temp 400-450°c
-Iron catalyst
What is the actual yield of a reaction?
The amount of product obtained when you carry out an experiment
How do you calculate the empirical formula of a compound?
-Mass of element/Ar
-Divide both by smaller one to find simplest ratio
-Find simplest whole number ratio
-Write out formula
What is the symbol for irritant?
What changes happen between them?
Solid - liquid = melting
Liquid - gas = evaporating
Solid - gas = sublimation
Gas - solid = deposition
Gas - liquid = condensing
Liquid - solid = freezing
What are the properties of covalent simple molecular compounds?
-Low melting and boiling point
-Poor conductor of electricity
-Often gas or liquid at room temperature
How did Mendeleev predict the existence and properties of elements yet to be discovered?
By observing patterns in his periodic table and leaving gaps where patterns didn't match
How are subatomic particles arranged in the nucleus?
-Proton and neutron in nucleus
-Electron on outer shells
What is the melting point of a pure substance?
Sharp, will melt at one specific temperature as all particles will change from solid to liquid at the same time because they have the same melting point
What are some physical properties of transition metals?
High melting point
High density
Malleable
Ductile (can be drawn through wire)
What does the symbol ⇌ mean?
It is a reversible reaction
What is the common reaction of metal with acid?
metal + acid → salt + hydrogen
What happens during electrolysis?
Compounds are split up using electricity
What is a molecule?
A group of non-metal atoms joined by covalent bonds
What are the names of some common molecular elements?
Oxygen
Hydrogen
What are the main features of a hydrogen-oxygen fuel cell?
-Fuelled by hydrogen and oxygen
-Only product is water
-Doesn't go 'flat', only stops when no more reactants are supplied
-Overall reaction is 2H2(g) + O2(g) → 2H2O(l)
How is ammonium sulfate made on a small scale?
1.Put some dilute sulfuric acid into a beaker.
2.Add a few drops of methyl orange indicator.
3.Add dilute ammonia solution drop by drop, stirring in between.
4.Continue step 3 until the colour permanently changes from red to yellow.
5.Add a few more drops of dilute ammonia solution.
6.Pour the reaction mixture into an evaporating basin, and heat carefully over a boiling water bath.
7.Stop heating before all the water has evaporated. Leave aside for crystals to form.
8.Pour away excess water and leave the crystals to dry in a warm oven (or pat dry with filter paper).
How do you calculate percentage yield of a reaction?
actual yield/theoretical yield x 100
What is the difference between empirical and molecular formula?
-Molecular formula is the actual number of atoms in one molecule of a substance
-Empirical formula is the simplest whole number ratio of elements in a compound
What is the symbol for harmful?
Why do covalent simple molecular compounds have low melting and boiling points?
They have weak intermolecular forces that can be broken easily
How were Mendeleev's ideas supported by later evidence?
In 1937 technetium was discovered with a relative atomic mass of 98. Mendeleev had left a gap in the table for an element with relative atomic mass of 98
Why are displacement reactions redox reactions?
redox = reduction and oxdiation happen
More reactive metals displace less reactive ones so electrons are transferred, meaning both reduction and oxidation happen
What is the arrangement and movement of particles in a solid?
-Regular placement
-Close together
-Vibrate around fixed positions
What is the movement of ions in electrolysis?
Cations (+) move to the cathode (-) and gain electrons
Anions (-) move to the anode (+) and lose electrons
What is the difference between an atom and an ion?
Atoms are not charged, whereas ions are charged
What is a dynamic equilibrium?
The reaction is happening both forwards and backwards at the same rate, and is dynamic because the chemical reaction is happening constantly and is moving
What is the melting point of a mixture?
Will melt over a range of temperatures
How are atoms of different elements different?
They have different numbers of protons
What are some chemical properties of transition metals?
Form coloured compounds - unlike group 1/2 that form colourless/white compounds
Colour of transition metal hydroxide can identify ion present in solution
Used as catalysts
How are ions in group 1 formed?
1 electron is lost to form a cation
What are the reactions at the electrodes in a hydrogen-oxygen fuel cell?
Cathode = 2H₂(g) →4H⁺+4e⁻
Hydrogen atoms oxidised to form ions
Anode = 4H⁺(aq)+4e⁻+O₂→2H₂O
Note 
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