C4

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  • C4
    • Atoms
      • All substances are made up of atoms.
      • Each atom has: A central nucleus (made up of protons and neutrons); electrons arranged in shells .
      • Atoms have the same number of protons and electrons (neutral)
      • Proton has the same mass as neutron
      • A substance that only has one type of atom is an Element
      • Elements in periodic tbale arranged in order of increasing atomic number
      • Electronic Configuration
        • Electrons in an atom occupy the lowest avalible shells
        • The first shell can only hold up to 2 electrons
          • The rest of the shells hold up to 8 electrons
            • Electronic Configuration
              • Electrons in an atom occupy the lowest avalible shells
              • The first shell can only hold up to 2 electrons
                • The rest of the shells hold up to 8 electrons
                • The amount of electrons in an outer shell determines what group of the periodic table its in
                • The chemical properties of an element are determined by its electron arrangment
          • The amount of electrons in an outer shell determines what group of the periodic table its in
          • The chemical properties of an element are determined by its electron arrangment
      • Spectroscopy
        • Light emitted from flame of element produces characteristic line spectrum
        • Each line in spectrum represents an energy change
        • Electrons falls from high energy levels to low.
        • Lithium - Red flame
        • Sodium - Yellow flame
        • Potassium - Lilac flame
      • Developing the periodic table
        • John Newlands (1864)
          • Only knew existence of 63 elements
          • Arranged elements in order of atomic mass
          • Found similar properties amongst every 8th element
          • Society ridiculed his idea
        • Dobereiner (1829)
          • Arranged elements into groups of 3 (triads)
          • Elements in a triad had similar chem. properties
          • R.A.M of middle one was halfway between other 2
          • Atomic mass was measured relative to hydrgens mas
      • Safety Precautions
        • Gloves
        • Eye protection
        • Wash hands after
        • Safety screens
        • Small amounts and low concentrations of chemicals
        • Work in fume cupboard/ventilating room
        • Not eating or drinking when working with chemicals
        • Not working near naked flames
      • Group 1 - The Alkali Metals
        • Metals become more reactive down the group
        • Low melting points
        • Melting and boiling points decrease down group
        • Alkali Metal Compounds
          • When the metals they react they form compounds that are similar
          • Reactions become more vigorous down group
        • Reactions with Chlorine
          • Reacts vigorously
          • Form colourless crystalline salts (metal chlorides)
          • Lithium + Chlorine = Lithium Chloride
        • Reaction with Water
          • Li, Na and K float on cold water (low density)
          • Heat from reaction turns Na and K into liquids
          • Fizz
            • Hydrogen gas formed
          • Down group, reaction more violent
          • Metal Hydroxide and Hydrogen gas formed
          • Alkali solution formed
          • Potassium + Water = Potassium Hydroxide + Hydrogen
        • Trends
          • Have similatr properties because same number of electrons in their outer shells
          • More reactive down the group because outer electron shell further away from influence of nucleys so an electron is lost more easily
      • Group 7 - The Halogens
        • Less reactive down the group
        • Higher melting and boiling points down group
        • All holagen consist of Diatomic pairs (pairs of atoms)
        • Chlorine
          • Green gas
          • Used to sterilise water
          • Make pesticides and plastics
        • Bromine
          • Orange liquid
          • Brown gas when heated
        • Iodine
          • Purple/dark grey solid
          • Pale purple gas when heated
          • Used as an antiseptic
        • Densities increase down group
        • Displacement Reactions
          • A more reactive halogen will displace a less reactive one from an aqueous solution of its salt
            • e.g. chlorine will displace bromine and iodine
              • Displacement Reactions
                • A more reactive halogen will displace a less reactive one from an aqueous solution of its salt
                  • e.g. chlorine will displace bromine and iodine
                  • potassium iodide + chlorine = potassium chloride + iodine
              • potassium iodide + chlorine = potassium chloride + iodine
              • Compounds
                • When they react, they form compounds that are similar
                • The reactivity decreases down the group
                • Halogens react with alkali metals and ions
                • Reaction between chlorine and iron is more vigorous than between iodine and iron.
              • Trends
                • They have similar properties because they have the same number of electrons in their outer shell
                • They are less reactive down the group because the outer electron shell is firther away from influence of the nucleus so an electron is gained less easily.
            • Properties of Compounds
              • Chemists use their observations to develop theories to explain the properties of different compounds
              • e.g. molten compounds of metals with non-metals (lithium chloride) conduct electricity
              • There are charged particles in molten compounds known as Ions
              • Ions
                • If an atom loses or gains one or more electrons it carries an overall charge because protons and electrons no longer equal
                • When this happens, atom becomes an ion
                  • If an atom loses or gains one or more electrons it carries an overall charge because protons and electrons no longer equal
                • If an atom loses an electron, the ions has a positive charge
                • If an atom gains an electeron, the ion has a negative charge
              • The Ionic Bond
                • An ionic bond occures between a metal and a non-metal
                • Involves the transfer of electrons between two atoms to from electrically charged ions
                • Each ion has a full outer shell
                • Compounds of Group 1 and 7 elements are ionic compounds
                • Sodium and Chlorine (Sodium Chloride)
                  • Bond ionically
                  • Sodium loses one electron (positive charge) and Chlorine gains the electron (negative charge)
                  • Positive and negative ions are then electrostatically attracted to eachother .
                  • Froms a giant crystal lattice
                • Sodium and Oxygen (Sodium Oxide)
                  • Oxygen wants two electrons and gains them from two sodium atoms
                • Magnesium and Oxygen (Magnesium Oxide)
                  • Mg loses two electrons and Oxygen gains two
                  • Forms crystals because ions arranged into a regular lattice
                • Ions have strong forces of attraction between them whcih takes a lot of energy to break
                • Ionic compounds have hugh melting and boiling points
                • When compound molten or dissolved, forces weakened and ions free to move - conduct electricity

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