Chemistry paper 1

• Element


  a substance containing only one type of atom
• Compound


  a substance containing two or more different types of atoms CHEMICALLY BONDED
• Mixture


  a substance containing two or more different atoms NOT CHEMICALLY BONDED
• Filtration


  removes large, insoluble particles from a liquid
• Evaporation


  1. Separating two liquids from each other

  2. leaves behind crystals of a dissolved substance
• Distillation


  involves condensing the evaporated solvent and collecting it
• Fractional Distillation


  can separate liquids due to their different boiling point
• Chromatography


  Causes substance to rise up paper and present what a substance is made out of.
• What did JJ Thomson create?

  The plum pudding model (positive charged with electrons dotted around it)
• What did Rutherford discover?

  the nucleus was small and positively charged (gold foil method - shooting alpha particles = most of the atom is empty space)
• Who discovered energy levels/ shells?

  Neils Bohr
• Who discovered Neutrons?


  Chadwick
• What does the atomic number represent?

  The smaller number represents the number of protons in a nucleus

  no. protons = no. electrons
• What does the mass number represent?

  The bigger number represents the number of protons + neutrons.

  Used to work out relative formula mass
• What did Mendeleev do that was different and made his period table more accurate?

  He left gaps in his table, which he predicted would be for undiscovered elements. This made his version the best and the most recognized.
• What do group numbers represent?

  The number of electrons in the outer shell
• What do the period numbers represent?

  Number of outer shells in an element
• Why does reactivity increase with the period number?

  Electrons are further away from the nucleus, meaning they are less controllable and more like to be lost
• What metals are in group 1?

  Alkali metals 1+ ions
• What is found in group 7?

  Halogens 1- ions
• Physical properties of elements in group 1

  1. soft

  2. malleable

  3. ductile
• What is found in group 0/8?

  Noble gases- very unreactive as they have a full outer shell
• What metals are found between groups 2-3?

  Transition metals- able to donate different number of electrons
• Structure of Metallic bonds?

  - Regular lattice arrangement of ions

  - Sea of FREE delocalised electrons
• Why are metals good conductors of heat and electricity?

  The delocalised electrons are free to move around
• What are Ionic bonds and how are they represented?

  - metals bonded with non metals

  - Dot and cross diagrams show how electrons are given up or received
• Structure of Ionic structures?

  - arranged in a LATTICE of repeating units of positive and negative ions
• Properties of Ionic Bonds

  - high melting and boiling points

  - due to strong ionic bonds (electrostatic forces)

  - can conduct electricity when molten or in a solution
• hydroxide ion


  OH-
• Hydrogen ion


  H+
• Sulphate ion


  SO4 2-
• Carbonate ion


  CO3 2-
• Nitrate ion


  NO3-
• Ammonium Ion


  NH4+
• Covalent Bonds


  - non metal + non metal

  - Share electrons to gain a full outer shell

  - the number of electrons it needs = bonds made
• Simple covalent bonds


  - low boiling and melting points

  - due to weak intermoleculer bonds

  - fewer covalent bonds (smaller structure)
• Giant Covalent Bonding


  - repeating units of atoms

  - very high melting and boiling points
• Diamond


  - hard

  - very strong repeating covalent bonds- carbon

  - structure looks like the shape of a diamond
• Graphite


  - Delocalised electrons form weak bonds between layers (graphene)

  - conduct electricity

  -Layers can slide past eachother
• Fullerenes


  - bucky balls

  - used for making lube

  - able to slide past multiple balls

  - structure looks like a ball

  - high surface area to volume ratio