A Level Chemistry - Bonding

The attraction between delocalised outer shell electrons and positive metal ions in a lattice

Endlessly reprating

Not associated with a particular atom

How many electrons are lost from each metal ion

The electrostatic attraction between oppositely charged ions in a lattice

Don't for ions (but will form covalent compounds)

Don't form ions

Sn4+ is most stable but can form Sn2+

Pb2+ is most stable but can form Pb4+

Form more than one stable ion

NH4 +

OH -

NO2 -

NO3 -

CN -

HCO3 -

HSO4 -

H2PO4 -

CO3 2-

SO3 2-

SO4 2-

HPO4 2-

PO4 3-

A shared pair of electrons

A pair of electrons which is not bonded

Molecules where the central atom doesn't have a noble gas electron arrangement eg BF3, SF6

A covalent bond in which both electrons of the shared pair come from the same atom

The atom that donates electrons has a lone pair. The atom that accepts the electron pair doesn't have a full outer shell (it is electron deficient) and can fit a lone pair

Using an arrow pointing from the the atom donating the electron

The total number of electron pairs around the central atom The number of bonding pairs of electrons The number of lone pairs of electrons

Pairs of electrons repel each other so that they as far apart as possible Lone pairs are more compact so repel more The molecule takes up a shape which minimises repulsion Lone pairs reduce bond angles by 2.5° each

Straight line

A wedge

Dotted line

Linear - 180°

Trigonal planar - 120°

Tetrahedral - 109.5°

Trigonal Bipyrimidal - 90° and 120°

Octahedral - 90° (and 180°)

Linear - 180°

Trigonal planar - 120°

V-shaped/bent - 117.5°

Trigonal pyramidal - 107°

V-shaped/bent - 104.5°

Trigonal planar - 120°

Square planar - 90°

Number of lone pairs and bond pairs and where. Electron pairs repel. Lone pairs repel more. State the bond angle and why

The power of an atom to attract the pair of electrons in a covalent bond

Increases as nuclear charge (proton number) increases

Decreases as the number of shells increases so atomic radius and shielding increases

Fluorine

When there is an uneven distribution of electrons

No or very small difference in electronegativity. The electron pair is shared equally with no dipole in the bond

H2, Cl2, O2, NaCl, CH

A difference in electronegativity. The electron pair is closer to the more electronegative atom, making it slightly negative

HCl CCl BeCl

A large difference in electronegativity. Electrons are pulled so far towards the electronegative atom that the less electronegative atom loses the electron

A small charge difference across a bond resulting from a difference in electronegativities of the bonded atoms

If they make the molecule electronically symmetrical eg CO2, the dipoles cancel out

The forces of attraction between molecules

These are the weakest intermolecular forces which occur between all substances between molecules of atoms

A constantly forming a disappearing dipole caused by the movement of electrons which unbalanced the charge distribution within the molecule

They only have van der Waals forces between molecules which are very weak

Bigger molecules have more electrons so the induced dipoles are large resulting in stronger forces

The random movement of electrons causes an instantaneous dipole across the molecule which indices a dipole in neighbouring molecules resulting in weak forces of attraction

Simple molecules and simple atomic substances

These occur between molecules which have a permanent dipole in addition to van der Waals forces. The negative pole of one molecule attracts another's positive pole. These are generally stronger than van der Waals forces

These are the strongest intermolecular forces which occur between molecules which contain a hydrogen atom bonded to either F, O or N. The bond forms between the slightly positive H atom in one molecule and a lone pair in the other

Higher boiling point than expected due to the strength of the hydrogen bonds Substances which can hydrogen bond tend to dissolve in water because they form hydrogen bond with water

The bonds

The intermolecular forces

Charged particles which are free to move such as delocalised electrons or ions

Substances can dissolve if dilute and solvent molecules attract one another - like dissolves like. Ionic and polar substances dissolve in polar solvent sand non polar substances dissolve in non polar solvents

A giant ionic lattice structure where negative and positive ions alternate so each ion is surrounded completely by oppositely charged ion held together by ionic bonds

The ions are held together by many strong ionic bonds that need a lot of energy to break

If enough force is applied, the layers can slide over each other. Like charges will move next to each other, causing repulsion which breaks down the lattice structure

The ions are only free to move in theses states so can carry current

Metallic bonds are generally strong so large amounts of energy is needed to break them

The delocalised electrons can move through the structure and carry the current

Metallic bonds are strong and extend through the giant metallic lattice structure

The size and charge of the metal ion (it's charge density). Smaller and more highly charged ions form stronger bonds

Can be hammered or pressed into shape without breaking or cracking

Can be drawn into thin wires

The layers of ions in the giant metallic lattice can slide over each other into new positions without disrupting the metallic bond

Simple molecular and macromolecular

The forces of attraction between molecules are weak. Not much energy is needed to break the intermolecular forces

They don't contain ions or delocalised electrons so can't carry a charge

Generally insoluble in water unless they can form hydrogen bonds with water or react with it

A giant arrangement of carbon atoms bonded to four other carbon atoms

A giant arrangement of carbon atoms bonded to three other carbon atoms in layers

A giant arrangement of carbon atoms bonded to four other carbon atoms

Many covalent bonds between all the atoms which take lots of energy to break

A single sheet of graphite

One electron per carbon isn't involved in bonding and is delocalised along the layer allowing it to carry a current

The covalent bonds are very strong and the lattice does not break up when any solvent is added