Chem P1 quiz

• Element


  Substance made from only one type of atom
• Compound


  Substance made from two or more different types of atoms chemically bonded together
• Mixture


  Two or more different elements or compounds that are not chemically bonded together
• Distillation to get pure water from salt water

  1. Heat solution so water (solvent) evaporates

  2. Use condenser to turn water vapour back into liquid, leaving salt (solute) behind
• Solid


  • Particles vibrate about fixed positions, tightly packed, cannot be compressed
• Liquid


  • Particles free to move past each other, still touching, cannot be compressed
• Gas


  • Particles move with fast speeds, high kinetic energy, far apart, can be compressed
• Rutherford discovered that atoms are mostly empty space with a small, positive charge in the middle (the nucleus)
• Subatomic particles


  • Protons (positive charge, relatively same mass as neutrons)
  • Neutrons (neutral charge, relatively same mass as protons)
  • Electrons (negative charge, very small mass)
• Atomic number


  Number of protons in the atom's nucleus
• Mass number (relative atomic mass)


  Number of protons plus neutrons in the nucleus
• Electron shell filling in atoms

  1. First shell max 2 electrons

  2. Second shell max 8 electrons

  3. Etc.
• Ionic bonding


  Metals donate their outer electrons to non-metals, leaving them with a positive charge
• Covalent bonding


  Non-metals share electrons to fill their outer shells
• Reactivity groups


  • Alkali metals (group 1, very reactive)
  • Halogens (group 7, get more reactive up the group)
  • Noble gases (group 0, very unreactive)
• Metallic bonding


  Metal atoms form a lattice with a 'sea' of delocalized electrons, making them good conductors
• The chemical formula for iron(III) oxide is Fe2O3
• Drawing structural formula and dot-and-cross diagram for methane

  1. Carbon makes 4 covalent bonds to hydrogen

  2. Structural formula shows bonds as lines, dot-and-cross shows electron pairs
• Ionic compounds


  • High melting points, can only conduct electricity when molten or dissolved
• Simple covalent compounds


  • Relatively low melting and boiling points, cannot conduct electricity
• Graphite can conduct electricity, diamond cannot, even though they are both giant covalent structures of carbon
• The relative formula mass of magnesium hydroxide is 58
• Limiting reactant


  The reactant that runs out first in a reaction
• Percentage yield


  Compares actual mass of product to theoretical mass
• Atom economy


  Compares mass of desired product to total mass of reactants
• Displacement reaction


  A more reactive metal or non-metal takes the place of a less reactive one in a compound
• Oxidation


  Loss of electrons
• Reduction


  Gain of electrons
• What is pH

  Measure of H+ ion concentration, lower pH is more acidic, higher pH is more alkaline
• Neutralisation reaction


  Acid + Alkali → Salt + Water
• Electrolysis


  Positive ions (cations) attracted to cathode, reduced

  Negative ions (anions) attracted to anode, oxidised
• In electrolysis, more reactive metals stay in solution and hydrogen is produced at the cathode
• Exothermic reaction


  Potential energy decreases, kinetic energy (temperature) increases
• Endothermic reaction


  Total bond energies of reactants > total bond energies of products, so energy is absorbed
• Dmitri Mendeleev arranged groups based on their properties
• Dmitri Mendeleev has gaps in his table, which he predicted would be filled by elements that hasn’t been discovered yet.
• the name of Group 1 elements are The Alkali metals
• Alkali metals are soft and have low densities. They are also very reactive as you go down group 1
• Alkali metals loses one electron to form a cation.
• alkali metals get more reactive down the group as the outer electron is further away from the nucleus so is lost more easily (the force of attraction is weaker)