Chemistry paper 1

• the reactivity series is the relative ability of metals to displace other metals from their compounds
• Alloys

  Many metals, such as copper, gold, iron and aluminium, are used in alloys. Many pure metals are too soft, so other metals are mixed in to make alloys harder. Alloys occur when metals have other metals or carbo atoms, the different sized atoms act as impurities and disrupt the reglar rows of atoms and stop them sliding over each other
• Advantages and disadvantages of nanoparticles

  Advantages: - can create new, more efficient tech - reduce carbon footprint - increase human lifespan and health - cheaper (use less material) Disadvantages: - can get into body (unknown effects) - uknown impact on humnas - potential contamination of food chains
• atomic number

  number of protons/electrons in an atom
• Small molecules

  Some elements and compounds with atoms that are joined by covalent bonds form small molecules
• Ionic bonds form when metals react with non-metals
• Atoms of metals lose their outer shell electrons
• These electrons are transferred to the non-metal atoms
• The atoms form oppositely charged ions with full outer shells
• The ionic bonds between the ions are strong
• Magnesium is a Group 2 metal with 2 outer shell electrons
• Oxygen is a Group 6 non-metal with 6 outer shell electrons
• Magnesium loses 2 outer shell electrons and becomes a 2+ ion
• Oxygen gains the 2 outer shell electrons from Magnesium and becomes a 2- ion
• The oppositely charged ions are attracted by strong forces of electrostatic attraction
• Ionic bonds between the oppositely charged ions are strong
• Properties of polymers

  • polymer molecules are very large - the intermolecular forces between the molecules are relatively strong compared with other covalent molecules - polymers have relatively high melting points - polymers are solid at room temp
• Group 1 reactions

  water - hydrogen and hydroxides oxygen - solid, white ionic oxides chlorine - solid, white ionic chlorides In general: metal + water - metal hydroxide + hydrogen e.g, for sodium: sodium + water - sodium hydroxide + hydrogen 2Na + H2O - 2NaOH + H2 metal + oxygen - metal oxide e.g, for lithium lithium + oxygen - lithium oxide 4Li + O2 - 2Li2O
• Early periodic table

  In the 19th century, scientisits knew about; the properties of elements, the atomic weights of elements. They didn't know about; protons, neutrons, electrons, atomic numbers. The early table: - listed elements in order of atomic weights - had 7 columns This table wasn't successful overall: - counting along, every 7th element had similar properties - this pattern failed after calcium - some metals, and non-metals were in the same column, such as oxygen and iron - there was no room for new, undiscovered elements
• protons, neutrons, electrons


  name of particle relative charge relative mass location proton +1 1 nucleus neutron 0 1 nucleus electron -1 very small shells
• Graphene is a single layer of graphite, one cell thick
• Uses of graphene:

  • Semiconductor, useful in electronics
  • Can be used to make composites that are strong and of low density
• Fullerenes are hollow cages of carbon atoms with spherical or other hollow structures based on hexagons of carbon
• Fullerenes may also have 5 carbon or 7 carbon rings
• Buckminsterfullerene (buckyballs) is C60 with a spherical molecule
• Uses of fullerenes:

  • In medicines to contain drugs
  • As lubricants due to weak intermolecular forces allowing layers to slide over each other
  • As a catalyst or surface for a catalyst
• Carbon nanotubes are cylindrical fullerenes that are very long compared to their diameter
• Carbon nanotubes have high tensile strength and are good conductors of electricity and heat
• Uses of carbon nanotubes:

  • In nanotechnology
  • In electronics due to high electrical conductivity
  • Making new materials
  • For reinforcing materials, such as in the frame of a tennis racket due to high tensile strength
• Properties of giant metal lattices

  High melting / boiling points: -strong electrostatic forces of attractio between positive metal ions and negative delocalized electrons -large amounts of energy need to overcome / break them Good conductivity: -delocalized electrons are free to move and carry charge / heat energy through the structure Malleable: -'sea' of delocalized electrons maintains the giant mettalic lattice as the rows slide -will follow the positive ions wherever they move (attracted to them)
• Properties of substances with small molecules

  1. the covalent bonds between atoms in a molecule are strong 2. the intermolecular forces between molecules are weak = melting/boiling points are low 3. the intermolecular forces increase with the size of the molecule These substances: 1. have low melting/boiling points 2. are usually gases or liquids 3. don't conduct electricity because they have no overall electric charge
• Uses of nanoparticles

  • in medicine to deliver drugs - in medicine as synthetic skin - in electronics - in cosmetics - in suncreams - as catalysts in fuel cells (due to large surface area) - in deodorants New applications are ebing researched. E.g silver nanoparticles in socks - antibacterial properties (becomes more reactive and interferes with bacterial cell wall)
• Modern periodic table

  After sub-atomic particles were discovered, the arrangement of the elements in the periodic table was seen to be in order of increasing atomic (proton) number - arranged periodically (ordered)
• Giant metallic structures

  Metals have giant structures of ions with strong metallic bonding. -metalic bonding is strong - lots of energy need to break them - high melting / boiling points -delocalized electrons - free to move - carry charge / heat
• Metallic bonds

  In metals: - the atoms lose their outer shell electrons, forming positive ions - the ions are in a regular, 3D arrangement: a lattice - the electrons from the outer shells move throughout the lattice - metallic bonding occurs in metals and alloys - the metallic bonds between the ions and the electrons are strong
• Relative formula mass


  The relative formula mass of a substance is the sum of atomic masses of all the atoms shown in the formula. Relative atomic mass has the symbol Mr and it has no units, just the number. E.g Mr of H2O = 2 + 16 = 18 Ar of H = 1 Ar of O = 16 The relative formula mass of a substance, in grams, is known s as one mole of that substance. 1 mole of H2O = 18g or 1 mole of O2 (oxgyen gas) = 32g Ar of O = 16 Mr of O2 = 32
• ionic compounds vs simple covalent

  ionic compunds - high melting point - high boiling point - conducts electricity when molten or in solution

  simple covalent

  -low melting point

  -low boiling point

  -doesn't conduct
• Metals

  -atoms have a few outer shell electrons - atoms lose electrons to form positive ions in ionic compounds - all metals (except mercury) are solid at room temp - all metals conduct
• Transition metals (properties)


  They have different properties to the group 1 alkali metals Properties Compared to the alkalis, the transition are: - have higher densities - have higher melting/boiling points (except for mercury) - are stronger and harder - are much less reactive with water, oxygen and halogens Many also: - form coloured compounds (alkali form white/colourless one) - are useful as catalysts (speed up reactions without being used up in them) - form more than one type of ions (e.g Fe can form Fe2+ or Fe3+)
• Properties which can differ between large scale versions of a material and its nanoparticle version -hardness -colour -electrical conductivity -chemical reactivity