AQA AS Chemistry Unit 1 Notes: Structure & Bonding, shapes of molecules, bond angles, ionic bonding, covalent bonding, metallic bonding, intermolecular forces, van der waals, induced dipole, polar

Some notes on AQA AS CHEM1 3.1.3 - Structure & Bonding, covering..

  • Ionic bonding
  • Covalent bonding
  • Metallic bonding
  • Intermolecular forces
  • Shapes of molecules


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Preview of AQA AS Chemistry Unit 1 Notes: Structure & Bonding, shapes of molecules, bond angles, ionic bonding, covalent bonding, metallic bonding, intermolecular forces, van der waals, induced dipole, polar

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Ionic Bonding
Occurs between metals and non-metals
Involves transferal of electrons from metal atoms to non-metal atoms
Positive and negative ions are formed
Electrostatic attraction holds positive and negative ions together ­ this is an
ionic bond
Always exist in a lattice structure
Property of ionic compounds Explanation
Do not conduct electricity when Ions are fixed in position by strong ionic
bonds. When molten or dissolved in water,
solid ions are free to move.
High melting/boiling points Giant lattice structure held together by strong
electrostatic attraction between ions which
requires lots of energy to break
Brittle and shatter easily Small displacement causes contact
between ions of same charge which
repel and structure shatters
Dissolve in water Polar water molecules pull ions
away from lattice and cause it to
Sodium chloride is an example of an ionic crystal with the above properties. (A
crystal is just a solid with a regular arrangement)
Definition of ionic bond: Electrostatic attraction between oppositely
charged ions
Covalent Bonding
Occurs between non-metals
Involves the sharing of outer electrons between atoms
Can form simple covalent (molecular) or giant covalent (macromolecular)
Property of simple covalent compounds Explanation
Do not conduct electricity No ions or delocalized electrons
Low melting/boiling points Weak intermolecular forces ­
covalent bonds do not need to be

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Iodine is an example of a molecular crystal with the above properties. The iodine
atoms pair up to form I2 molecules, held together by strong covalent bonds.
Intermolecular forces between the I2 molecules hold the crystal together.
There are two main carbon macromolecular structures: graphite and diamond.
These are allotropes of carbon.
The carbon atoms in graphite are arranged in sheets of flat hexagons. The carbon
atoms form three bonds each and the fourth outer electron of each carbon atom is
delocalized.…read more

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Metallic Bonding
Metal elements form giant metallic lattice structures
Outer shell of electrons of each metal atom is delocalized
Metal atoms become positive metal ions
Positive metal ions attracted to delocalised electrons
Closely packed metal ions among `sea' of delocalised electrons
Property of metals Explanation
High melting/boiling points Giant structure, strong attraction
between ions and electrons- the
more delocalised electrons per
atom, higher mpt/bpt.…read more

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Increases across a period as more electrons become delocalized
Decreases down a group as the atomic radius increases
Magnesium is an example of a metallic crystal with the above properties. Each
magnesium atom loses their 2 outer electrons to become Mg2+ ions.
Intermolecular Forces
There are three types of intermolecular force to know (in order of ascending
1. Van der Waals forces (Induced dipole-dipole)
2. Permanent dipole-dipole forces
3.…read more

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These atoms are highly
electronegative, and so attract the
bonding electrons towards them in the
covalent bond. The hydrogen atom then
has a high charge density (because the
atom is so small and positively charged),
resulting in it forming strong
intermolecular forces with F, N or O
atoms on other molecules called
hydrogen bonds. (Note: not stronger
than a covalent bond).…read more

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Remember that the biggest angles are between two lone pairs. Lone pair/bonding
pair angles are the second biggest, and bonding pair/bonding pair angles the
smallest.…read more


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