bonding Flashcards
ionic bonding
oppositely charged ions attract through electrostatic forces to form a giant ionic lattice
sulfate formula
SO4 2-
hydroxide formula
OH-
nitrate formula
NO3 -
carbonate formula
CO3 2-
ammonium formula
NH4 +
single covalent bond
shared pair of electrons between two outer shells in order to achieve full outer shell
multiple covalent bond
multiple pairs of electrons shared
co-ordinate (dative covalent) bond
shared pair of electrons with both electrons supplied by one atom
how to represent covalent or coordinate bond
covelant using a line
coordinate using an arrow from the lone electron pair
metallic bonding
strong electrostatic force of attraction between delocalised electrons and positive ions arranged in a lattice
four types of crystal structure
ionic
metallic
macromolecular
simple molecular
crystal structure of diamond
macromoleular
crystal structure of graphite
macromolecular
crystal structure of ice
simple molecular
crystal structure of iodine
simple molecular
crystal structure of magnesium
metallic
crystal structure of sodium chloride
ionic
MP of macromolecular structures
very high mp as multiple covalent bonds to overcome which are very strong
MP and conductivity of simple molecular
usually low mp due to IDD but depends if PDD or hydrogen bonding
very poor conductors as no charged particles
MP and conductivity of ionic strucutres
high MP as strong electrostatic forces
conducs electricity in molten or solution as ions seperate so free to move and carry a flow of charge
MP and conductivity of metallic substances
high mp due to strong electrostatic forces of attraction
high melting poins nealry alwasys solid at room temp
explain the energy changes associated with changes of state
as temp rises kinetic energy of the particle increases
bonding pairs and lone pairs of electrons are
charge clouds that repel each other
arrangement of pairs of electrons in outershell of atom
arrange themselves as far apart as possible to minimise repulsion
lone pair, bond pair replusion comparison
lone pair-lone pair repulsion> lone pair- bond pair> bond pair-bond pair
effects of electron pair replusion on bond angles
lone pair- lone pair replusion reduced the bond angle
bonding pairs , lone pairs , bond angle of linear
2
0
180
bonding pairs , lone pairs , bond angle of trigonal planar
3
0
120
bonding pairs , lone pairs , bond angle of tetrahedral
4
0
109.5
bonding pairs , lone pairs , bond angle of trigonal biprymidal
5
0
120 and 90
bonding pairs , lone pairs , bond angle of octahedral
6
0
90
bonding pairs , lone pairs , bond angle of v-shape
2
1
117.5
and
2
2
104.5
bonding pairs , lone pairs , bond angle of see-saw
4
1
119 and 89
bonding pairs , lone pairs , bond angle of square pyramidal
5
1
89
bonding pairs , lone pairs , bond angle of triangular pyramid
3
1
107
bonding pairs , lone pairs , bond angle of t-shape
3
2
89
bonding pairs , lone pairs , bond angle of square planar
4
2
90
electronegativity
the power of an atom to attract the pair of electrons in a covalent bond
trend in electronegativity down a group and across a period
decreases down a group as shielding increases
increases across a period as atomic radius decreases
causes of permentant dipole
electron distribution in a covalent bond between elements with different electronegativities will be unsymmetrical which produces a polar covalent bond and may cause molecule to have permentant diploe
explain why some molecules with polar bonds do not hvae a permentant dipole
non-polar molecule may still contain polar bonds and the presence of symmetrical bonds in a molecules means that the delta charges cancel each other out so no permentant diople formed
3 main types of intermoleuclar forces
induced dipole dipole
permeant diploe dipoles
hydrogen bonding
how are melting and boiling points of simple molecular substances influenced by the strenth of these intermolecular forces
IDD- weakest type of intermolecular force, larger the mr the stronger the intermolecular force higher the melting point (generally lower mp though)
PDD- stronger intermolecular forces than IDD weaker than hydrogen bonding of similar sized molecules, mid melting and boiling point
Hydrogen bonding- much higher melting and boiling points compared to similar sized molecules without hydrogen bonding
how does hydrogen bonding arise
forms between hydrogen and the 3 most electronegative atoms(nitrogen, oxegon and flourine). the lone pair on NOF attracted to the delta positive on hydrogen (shown with a dotted line)
importance of hydrogen bonding in the low density of ice and anomalous boiling points of compounds
low densisty of ice- water molecules become arranged into 3D networks where each water molecule is connected to 4 other water molecules by hydrogen bonds so the water molecules in solid ice are further apart than the molecules in liquid water
anomalous boiling point- requires more energy to break its hydrogen bonds before it can begin to boil
