Ozone story

define Electronegativity

the ability of an atom to attract bonding electrons in a covalent bond

explain the electronegativity trends

increases across periods and decreases down the group

F, O ,Cl, N, C, H

why are some bonds non-polar

if 2 atoms have the same electronegativity then the e- are shared equally so the bond isn't polar (C-H bonds are considered non-polar)

why are some bonds polar

if two atoms with different electronegativity bond the e- are shared unequally causing an uneven distribution of charge

why are some atoms partially negative

the e- will be closer to atom with higher electronegativity so this atom will be partially negative

why isn't CO2 polar

if the polar bonds are arranged so they point in opposite directions they cancel each other out

define intermolecular forces

forces of attraction between molecules (weak)

Explain instantaneous dipole-induced dipole forces (id-id)

the random movement of all electrons causes them to have a temporary uneven distribution of charge, this then induces a dipole in neighbouring molecules because the electrons are constantly moving the dipole is constantly created and destroyed

how does Mr affect the IDs-IDs

larger molecules have more electrons so are more polar and therefore have stronger IDs-IDs

(this means they have higher melting and boiling points)

how does the shape of the molecule affect IDs-IDS

the more linear the shape of a molecule the closer the electrons can pack together meaning more contact causing stronger IDs-IDs

(this means they have higher melting and boiling points)

how does length of the molecule affect IDs-IDs

the longer the chain the greater the molecule surface contact and more electrons so stronger IDs-IDs

Explain permanent dipole- permanent dipole forces (PDs-PDs)

the partially positive and negative charges on polar molecules cause weak electrostatic forces of attraction between molecules

*happen as well as ID-IDs

*second strongest IMFs

explain the charged rod experiment

if you put an electrostatically charged rod next to a jet of polar liquid it will move towards the rod because the polar liquid have PD-PDs

explain hydrogen bonding

N,F,O are so electronegative they draw bonding electrons away from the H atom because the bond is so polarised and H has a high charge density the atoms form weak bonds with the lone pairs

* very high melting and boiling points

how to draw hydrogen bonding

*partial charges

*lone pair

*correct atoms

*a 180 degree angle

why is ice less dense than water

in ice the water molecules are arranged so there is the maximum amount of hydrogen bonds (lattice) when it melts some of the hydrogen bonds are broken allowing molecules to fill the space