Electrons Bonding and Structure

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  • Electrons Bonding and Structure
    • bonding
      • ionic bonding
        • between  a metal and non-metal
          • metal is positive
          • non-metal is negative
            • therefore are attracted to each other
              • metal is positive
        • you will need to be able to draw dot and cross diagrams- but you try drawing them on a mind map!
        • they will form giant ionic lattices
          • each ion is surrounded by oppositely chargedions
          • eg, salt
        • Ions
          • Must know: NO -3,      CO3 -2,   SO4 -2     NH4 +1
          • you can predict the ions that will form based on the position in the periodic table
            • groups 1-3 will loose electrons andform a positive ions
            • groups 5-7 will gain electrons and will form negative ions
      • covalent bonding
        • Between two non-metals
        • two electrons will be shared between two atoms
        • Some atoms will share more than 1 electron
          • Known as a multiple bond
        • A lone pair is a pair of outer shell electrons not involved in bonding
        • a dative covalent bond is when one atom supplies both electrons
      • intermolecular forces
        • electronegativiity
          • the measure of attraction of the bonded atom to the electrons in a covalent bons
          • this causes electrons to be further one way then the other and cause the molecule to be polar
            • this causes dipoles
              • the measure of attraction of the bonded atom to the electrons in a covalent bons
        • van der Waals'
          • electrons move within a bond
            • this means at any point a instantaneous dipole could  be created
              • this then induces a dipoles in the neighbouring molecules
                • these are then attracted to each other
          • relatively weak
          • eg, gecko's foot
        • Hydrogen Bonding
          • Strongest intermolecula force
          • Forms between a hydrogen and a O or a N
          • Holds DNA double helix together
      • noble gasses
        • they have a full outer shell
        • makes up 1% of the air
        • argon is the most abundant
      • electronegativiity
        • this causes electrons to be further one way then the other and cause the molecule to be polar
          • this causes dipoles
      • structure
        • Shapes of molecules and ions
          • all electrons are negative and will repel each other as far away as possible
          • 3 covalent bonds= trigonal planar 120° bond angel
          • 4 covalent bonds = tetrahedral 109.5° bond angel
          • 6 covalent bonds = octahedral 90° bond angel
          • Lone pairs are more negaive and therefore push the  bonds away and reduce bond angels
        • Metallic
          • positive ions are fixed in place
            • these hold the positive ions together
          • outer shell electrons form a sea of delocalised electrons
            • these hold the positive ions together
            • they are able to move within the structure
            • you can not tell which ion the electron originated from
            • overall the charges MUST ballance
              • positive ions are fixed in place
            • they have high melting and boiling points
              • this is because whilst the electrons can move the ions are held in place and take a lot of energy to disturb
            • they conduct electricity
              • because the electrons are free to carry a charge
            • they have a degree of give due to electrons being able to move, this gives them properties such as malleability
            • alloys-they have different sized ions so the layers of the metal cannot sld
          • Ionic compounds
            • form giant ionic lattices
              • each ion is surrounded by oppositely charged ions
                • this forms a "grid"
              • high melting oint
                • because a large amount of enery is needed to break the strong electrostatic attraction between ions
              • the can only conduct electricity when they are a liquid
                • because the ions are free to move and carry a charge
              • wil only dissolve in polar solvents
                • because the polar molecules will surround each ion and keep them apart
          • Covalent compounds
            • a simple molecular lattice
              • individual molecules held together by intermolecular forces
              • low melting and boiling points
                • intermolecular forces are weak
            • A giant covalent lattice
              • a 3D structure held together by covalent bonds
                • they are insoluble they don't conduct electricity and have a high melting point
                  • except graphite
                    • sheets of covalently bonded atoms held together in layers by van der waals' forces
                    • it can conduct due to delocalised  electrons between layers
                    • soft due to sheets moving
              • Eg, diamond
        • Electrons
          • Shells and orbitals
            • Ionisation
              • a mixture of positive ions and negative electrons is called plasma
              • First  ionisation energy is the energy to remove one electron from each atom in one mole of GASEOUS atoms
                • Ionisation energy is effected by 3 things
                  • 1.Atomic radius
                  • 2. Nuclear charge
                  • 3. Electron shielding
                • Successive ionisation energy- energy for electrons in turn
              • Successive ionisation energy- energy for electrons in turn
              • A  large jump in ionisation energies means a new shell
            • Orbitals
              • Can hold 2 electrons
              • S orbital
                • spherical shape
              • p Orbital
                • Dumb bell shape that come in threes
              • D orbital
                • Come in  fives
              • F Orbital
                • Come in sevens
              • the  two  electrons have opposite spins
            • a shell is a group of orbitals with the same QUANTUM number
              • Orbitals
                • Can hold 2 electrons
                • S orbital
                  • spherical shape
                • p Orbital
                  • Dumb bell shape that come in threes
                • D orbital
                  • Come in  fives
                • F Orbital
                  • Come in sevens
                • the  two  electrons have opposite spins
              • Each shells can hold 2n² electrons
          • Sub Shells
            • a group  of the same type of orbital within a shell
            • when working out configuration:
              • Electrons are added one at a time
              • The lowest energy level is filled first
              • fill each energy level completely before starting the next
          • The Periodic table
            • Electron shells can overlap
            • the periodic table is split into bocks
              • you can then count along to work out the orbital configuration

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