Bonding and structure
- Created by: LauraNannini
- Created on: 16-04-20 08:03
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- Topic 2
- Ionic bonding
- Metals + non-metals
- Make giant lattice structures
- Strong electrostatic forces of attraction between oppositely charges ions
- Possitive ions are bigger than negative ions
- Going down a group the ionic radii increases
- Evidence for ions
- Electron density maps show the separate ions
- Force will cause ions to move and repel to form seperate layers
- Ionic compounds physical properties
- High melting points
- Non-conductor of electricity when solid- tightly packed together
- Conductor of electricity when molten- ions are free to move
- Covalent bonding
- Caused by electrostatic attraction between shared pairs of electrons
- Properties of covalent bonding
- Allotropes of carbon like diamond and graphite have extremely high melting points
- Multiple bonds
- Greater forces of attractions
- Shorter bond length
- Greater bond strength
- Dative covalent bonds
- Shared pair of electrons both come from only one of the atoms
- Arrows from one atom to the other shows a dative bond
- Shape of molecules
- Linear- BP2 LP0 180 degrees
- Trigonal planar- BP3 LP0 120 degrees
- Tetrahedral- BP4 LP0 109.5 degrees
- Trigonal pyramidal- BP3 LP1 107 degrees
- Bent- BP2 LP2 104.5 degrees
- Trigonal Bipyramidial- BP5 LP0 120 and 90 degrees
- Octahedral- BP6 LP0 90 degrees
- Electronegativity and intermediate bonding
- Tendency of an atom in a covalent bond to attract electrons in a covalent bond to itself
- Symetrical molecules are not polar
- >1.7 pauling scale = ionic- anything below is covalent
- Fluorine is the most electronegative
- Tendency of an atom in a covalent bond to attract electrons in a covalent bond to itself
- Metallic bonding
- Electrostatic forces of attraction between positive metal ions and delocalised electrons
- The smaller the ions the stronger the metallic bond
- The more protons the stronger the bond
- The more delocalised electrons the stronger the bond
- Properties of metallic bonds
- Brittle due to their layered structure
- Malleable due to layers can slde over each other
- Ionic bonding
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