Electron Structure

Energy levels/ Quantum shells
1. Principle Quantum number
  1. Describes the position of the shell in the atom.
  2. The larger the principle quantum number is the further away it is from the nucleus,
  3. 1n
    1. Energy level - 1
    2. Maximum number of electrons - 2
  4. 2n
    1. Energy level - 2
    2. Maximum number of electrons - 8
  5. 3n
    1. Energy level - 3
    2. Maximum number of electrons- 18
  6. 4n
    1. Energy level - 4
    2. Maximum number of electrons - 32
Orbitals and Subshells
1. S-Subshell
  1. Spherical shape
  2. Has just 1 orbital
    1. Holds up to 2 electrons
2. P-Subshell
  1. Consists of 3 orbitals
    1. Orbitals are dumbbell shaped
  2. Holds up to 6 electrons
3. D-Subshell
  1. Consists of 5 orbitals
  2. Complex shape
  3. Holds up to 10 electrons
4. F-Orbitals
  1. Complex shape
  2. Consists of 7 orbitals
  3. Holds up to 14 electrons
5. Definition: An atomic orbital is the volume of space within an atom that can hold up to 2 electrons with opposite spins
  1. Key definition: A covalent bond is the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atom
    1. Key definition: A dative bond is a bond where the shared pair of electrons has been donated by the same atom
      1. The ammonium ion contains a dative bond
      2. The oxonium ion contains a dative bond
      3. Definition: A simple covalent lattice is a 3-d structure of molecules bonded together by weak IMF
        Definition: A giant Covalent lattice is a 3d lattice structure of atoms bonded together by strong covalent bonds
Periodic table
1. Arranged based on the reactivity and properties of elements
  1. Reactivity is dependent on outer shell electrons
2. Can be divided into blocks depending on which subshell contains the outermost electron
  1. Group 1 and 2 are the S-block
  2. The transition metals are the D-block
  3. Group 3 to 0 are the P-block
Box diagrams
1. As orbitals have varying shapes they are often represented as boxes
2. Each box can hold up to 2 electrons which are represented as arrows
  1. ^ l l v
    1. ^ l
      1. ^ l
3. 1) Electrons should be added one at a time 2) the lowest available energy level is to be filled first 3) Each energy level must be filled before the higher energy level is filled 4)When a subtle is filled up with electrons each orbital is filled singularly before pairing starts 5) An orbital can hold up to 2 electrons, each with opposite spins.
Electron configurations
1. s
  1. 1
    1. Number of electrons in subshell
  2. 1
    1. Principle Quantum Number
  3. Sub-shell type
Bonding
1. Metallic
  1. positively charged ions held together by a sea of delocalised electrons
  2. Properties
    1. Conducts electricity
      1. delocalised electrons free to move and carry the charge
    2. Insoluble in water
      1. No interactions with water molecules
    4. Variable melting and boiling points
      1. the more positive the ion the more it attracts the electrons the higher the melting point
2. Covalent
  1. Simple molecular structures
    1. Molecules held together by weak IMF
    2. Atoms bonded by strong covalent bonds
    3. Properties
      1. Low melting and boiling points
        Weak IMFS need little energy to overcome
      2. Not conductors of electricity
      3. Soluble only in non polar substances
        Forces between solvent and covalent molecule weaken lattice and it dissolves
  2. Macromolecules
    1. Millions of atoms bonded by millions of strong covalent bods
    2. Properties
      1. High melting and boiling point
        Strong covalent bonds need a lot of energy to overcome
      2. Non-soluble
        No interaction between water molecules
      3. Conductivity?
        Only graphite (delocalised e- move through and carry the charge)
3. Ionic
  1. Definition: Ionic bonding is the electrostatic force of attraction between positive and negative ions
  2. Takes place between metals and non-metals
    1. Metal forms a positive ion by losing electrons
      1. Cations
    2. Non-metal forms a negative ion by gaining electrons
      1. Anions
    3. Attraction between ions depends on, Charge and Size
      1. The larger the charge the larger the force of attraction
      2. The smaller the atom the larger the force of attraction
  3. 1. In exam only the 2nd half of this diagram is needed
    2. Metal ion should always have an empty outer shell (this isn't shown on this diagram)
  4. Structure
    1. Ionic compounds form Giant ionic lattices
    2. 1. Each Cl ion is surrounded by 6 Na ions and vice versa
        6:6 Cordination
      2. Each ion is attracted by the oppositely charged ions surrounding it
        Only draw the outer shell
        Only the final diagram needs to be drawn in an exam
        Double and triple covalent bonds are also possible
  5. Properties
    1. High melting and boiling points
      1. Solid at RT
      2. Large amounts of energy are required to overcome the strong electrostatic forces between ions
    2. Conducts electricity IN SOLUTION
      1. When solid ions are in fixed positions and can't move through the structure therefore cannot carry the charge
        When in solution the lattice has been broken down so the ions are free to move and carry the current
    3. Soluble in water
      1. Polar water molecules break down lattice by surrounding each ion by water molecules forming a solution

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	Created by Alice Butterworth almost 9 years ago