GCSE Chemistry Edexcel Paper 1

• What are the 3 states of matter?

  1. 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 matchSee an expert-written answer!We have an expert-written solution to this problem!
• 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