thirds

• what is a solvent?

  a liquid in which solutes can dissolve
• what is a solute?

  a substance that dissolves in a solvent
• what is a solution?


  made from a solute dissolved in a solvent
• what is a saturated solution?

  a solution that can dissolve no more solute at that temperature
• what is an element?

  a substance containing only one type of atom
• what is a compound?

  a substance containing two or more types of atoms chemically combined
• what is a mixture?

  two or more substances mixed but not chemically combined
• a pure substance has a fixed melting and boiling point, whereas a mixture may melt or boil over a range of temperatures
• simple distillation?

  solution heated so water evaporates and leaves behind salt
• fractional distillation?

  separates a mixture of different liquids with different boiling points
• filtration?

  separating an insoluble solid from a liquid - filter paper
• crystallisation?

  heat solution so it leaves behind a saturated solution, leave to cool and crystals will form
• what is a molecule?

  two or more atoms joined together with covalent bonds
• in an atom, the number of electrons and protons are equal
• mass of proton = 1, neutron = 1, electron = 1/1836
• charge of proton = +1, neutron = 0, electron = -1
• the atomic number (the smaller number) tells us the number of protons
• the mass number (larger number) tells us the number of protons and neutrons combined
• isotopes have the same number of protons but different numbers of neutrons
• ions are electrically charged particles formed when atoms lose or gain electrons
• sulfate charge?

  -2
• carbonate charge?

  -2
• nitrate charge?

  -1
• hydroxide charge?

  -1
• ammonium charge?

  +1
• silver ion charge?

  +1
• zinc ion charge?

  +2
• hydrogen ion charge?

  +1
• copper (II) ion charge?

  +2
• iron (II) ion charge?

  +2
• iron (III) iron charge?

  +3
• lead (II) ion charge?

  +2
• ionic bonding is a strong electrostatic attraction formed between oppositely charged ions
• ionic compounds have high melting and boiling points because they have a giant structure with strong electrostatic forces between oppositely charged ions that require a lot of energy to break
• a covalent bond is formed between two atoms by the sharing of a pair of electrons in order to fill their outer shells
• diamond is a giant covalent structure with many strong covalent bonds that require a lot of energy to break. each carbon atom is covalently bonded to four other carbon atoms.
• graphite can conduct electricity because its delocalised electrons are free to move. each layer of graphite is a giant structure, with weak forces of attraction between the layers, allowing them to easily slide over each other
• C60 fullerene has a low melting point and is soft because the molecule has weak intermolecular forces of attraction between the carbon atoms which take little energy to overcome
• covalent compounds don't usually conduct electrically because they don't have any delocalised electrons
• metal + water -> metal hydroxide + hydrogen