AQA AS Chemistry Unit 1 Foundation Chemistry – Flashcards

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question
Define electronegativity.
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The power of an atom to withdraw electron density from a covalent bond
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Define the term relative atomic mass of an element. (1)
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average mass of one atom of an element x12
mass of one atom of carbon-12
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Describe and explain the trend in boiling and melting points going across period 3.
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Across the metals (Na, Mg, Al) MP and BP increase as the number of delocalised electrons increases, making metallic bonding stronger. Si has a high MP and BP due to its giant covalent structure. In the non-metals with simple molecular structures, MP and BP are dependent on the size of the molecule: the greater the molecular surface area, the stronger the van der Waals forces between molecules, so the higher the MP and BP.
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Explain how NO is produced in the engine of a motor vehicle. (2)
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Nitrogen and oxygen in the air react (1) at high temperatures/with a spark (1).
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Explain why the value of the first ionisation energy of sulfur is less than the value of the first ionisation energy of phosphorus.
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Paired electrons in the 3p subshell of sulfur repel. In phosphorus there are no paired electrons in the 3p subshell.
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For a metal, is the atomic or ionic radius bigger and why?
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Atomic; outer shell is emptied when an ion is formed
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For a nonmetal, is the atomic or ionic radius bigger and why?
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Ionic; extra repulsion causes the charge cloud to expand
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How many structural isomers does butane have?
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2
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How many structural isomers does pentane have?
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3
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How many structural isomers does hexane have?
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5
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List four pollutants produced by burning fuels.
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Sulfur dioxide, carbon monoxide, particulates and nitrous oxides.
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Name the homologous series with the functional group -OH.
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Alcohols
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Name the homologous series with the functional group C=C.
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Alkenes
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Name the homologous series with the functional group R-CO-R.
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Ketones
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Name the homologous series with the functional group R-COH.
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Aldehydes
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Name the homologous series with the functional group R-COOH.
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Carboxylic acids
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Give two problems associated with the emission of sulfur oxides.
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Acid rain; causes problems for people with asthma.
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State a use of ethene.
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Making plastics/used to make polyethene
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State the meaning of the term structural isomers. (2)
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Compounds which have the same molecular formula (1) but different structural formula (1)
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State the shape and bond angle in a molecule of BF3.
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Trigonal planar; 120
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State the shape and bond angle in a molecule of CO2.
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Linear; 180
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State the shape and bond angle of ClF4-.
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Square planar, 90o
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State the shape and bond angle of H2O
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Non-linear; 104.5
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State the shape and bond angle of NH3.
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Trigonal pyramidal/distorted tetrahedral; 107
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State the shape and bond angle of NH4+
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Tetrahedral; 109.5
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State the shape and bond angle of SF6.
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Octahedral; 90
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State the shape and bond angles of PCl5.
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Trigonal bipyramidal; 120,90
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What are the conditions for catalytic cracking?
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450oC, up to 10atm, zeolite catalyst
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What are the conditions for thermal cracking?
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Up to 900oC, 70atm
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What are the five steps of mass spectrometry?
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Vaporisation, ionisation, acceleration, deflection, detection
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What are the main products of catalytic cracking?
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Motor fuels and aromatic hydrocarbons
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What environmental problems result from nitrous oxide pollutants?
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Acid rain and photochemical smog
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What happens to atomic radius across a period and why?
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It decreases due to increased nuclear charge.
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What happens to electronegativity across a period and why?
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Increases; greater nuclear charge to attract electrons
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What is a free radical?
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An atom or molecule with an unpaired electron
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What is a functional group isomer of an alkene?
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A cycloalkane.
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What is the charge on a barium ion?
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2+
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What is the charge on a calcium ion?
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2+
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What is the charge on a carbonate ion?
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2-
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What is the charge on a hydrogen ion?
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1+
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What is the charge on a hydroxide ion?
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1-
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What is the charge on a lead ion?
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2+
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What is the charge on a lithium ion?
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1+
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What is the charge on a magnesium ion?
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2+
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What is the charge on a nitrate ion?
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1-
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What is the charge on a potassium ion?
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1+
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What is the charge on a silver ion?
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1+
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What is the charge on a sodium ion?
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1+
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What is the charge on a sulphate ion?
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2-
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What is the charge on a sulphide ion?
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2-
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What is the charge on a zinc ion?
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2+
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What is the charge on an aluminium ion?
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3+
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What is the charge on an ammonium ion?
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1+
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What is the charge on an oxide ion?
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2-
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What is the economic reason for the cracking of crude oil?
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To produce substances which are in greater demand.
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The electron configuration of Vanadium (V) is (1s^2)(2s^2)(2p^6)(3s^2)(3p^6)(3d^3)(4s^2).What is the electron configuration of a V3+ ion?
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(1s^2)(2s^2)(2p^6)(3s^2)(3p^6)(3d^2)
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What does it mean for two species to be isoelectronic?
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They have the same electron configurations
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What is the electron configuration of chromium and why does it defy the trend?
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1s^2.2s^2.2p^6.3s^2.3p^6.3d^5.4s^1; the 4s subshell promotes an electron to the 3d to become more stable.
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What is the electron configuration of copper and why does it defy the trend?
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1s^2.2s^2.2p^6.3s^2.3p^6.3d^10.4s^1; the 4s subshell promotes an electron to the 3d subshell to become more stable.
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What is the ideal gas equation?
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pV=nRT
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What is the main advantage of catalytic cracking over thermal cracking?
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Lower temperature and pressure - lower cost.
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What is the trend in ionisation energy going down a group? (3)
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Ionisation energy decreases. (1) The atomic radius increases (1) and there is more electron shielding as you go down the group (1)
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What is used to remove sulphur dioxide emissions and why?
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Calcium oxide; it is basic so it neutralises the gas.
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What metal is used as a catalyst in a catalytic converter?
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Platinum
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What three factors affect ionisation energy?
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Nuclear charge, atomic radius and shielding
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What type of catalyst is used in catalytic cracking?
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Zeolite
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What type of cracking produces lots of alkenes?
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Thermal cracking
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What type of crystal structure does graphite have?
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Giant covalent/macromolecular
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What type of mechanism is catalytic cracking?
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Carbocation mechanism
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What type of reaction is thermal cracking?
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A free radical reaction.
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When forming positive ions, which empties first - the 3d subshell or the 4s subshell?
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4s
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Why do the boiling points of nonmetals increase down a group?
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Larger molecules = stronger van der Waal's forces
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Why does an alkene have a similar boiling point to its alkane equivalent with the same number of carbon atoms? (2)
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Similar molecular surface area (1), so similar van der Waal's forces between molecules (1)
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Why does ionisation energy drop slightly between groups 2 and 3?
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The p subshell is further from the nucleus than the s subshell
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Why does ionisation energy drop slightly between groups 5 and 6?
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Paired electrons in the p subshell repel
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Why does ionisation energy increase across a period?
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Decreased atomic radius and increased nuclear charge.
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Why does thermal cracking require large temperatures?
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To break C-C and C-H bonds
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Why is platinum coated on a ceramic honeycomb in a catalytic converter?
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Maximised surface area
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Why is the boiling point of iodine low? (2)
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Van der Waals forces between molecules (1) are weak (1)
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Write an equation to show how NO is removed from the exhaust gases in motor vehicles using a catalytic converter.
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2NO+2CO=>N2+2CO2
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