DEFINITION The electrostatic force of attraction between oppositely charged ions
Usually occurs when a metal bonds with a non-metal Ions are formed by complete electron transfer from the metal atoms to the nonmetal atoms Ions have a noble gas or other stable electronic configuration
DOT and CROSS DIAGRAM [ Na ] + [ Cl ] -
DOT and CROSS DIAGRAM [ Ca ] 2+ 2[ Cl ] -
DOT and CROSS DIAGRAM 2[ Na ] + [ O ] 2-
Ionic compounds have a giant lattice structure
Ionic compounds have a giant lattice structure
Ionic compounds have a giant lattice structure
Ionic compounds have a giant lattice structure High melting points May dissolve in water Solid does not conduct electricity Conduct electricity when molten or dissolved in water
DEFINITION A shared pair of electrons One provided by each atom joined by the bond
Usually occurs when atoms of two nonmetals bond together Atoms achieve a noble gas or other stable electronic configuration
DOT and CROSS DIAGRAM Cl Cl
DOT and CROSS DIAGRAM O O
DEFINITION A shared pair of electrons Both provided by only one of the bonded atoms
Occurs when there is an atom with a lone pair of electrons to donate and an atom with room to accept a lone pair Once formed it is the same as a covalent bond Atoms achieve a noble gas or other stable electronic configuration
DOT and CROSS DIAGRAM H + H N H H
PRINCIPLES Electron pairs repel each other as much as possible Lone pairs repel more than bonding pairs Multiple bonds behave like single bonds
Electron pairs repel each other as much as possible Bonding pairs Lone pairs Diagram Bond angle / 0 Name 2 0 180 Linear 3 0 120 Trigonal planar 4 0 109.5 Tetrahedral 6 0 90 Octahedral
Lone pairs repel more than bonding pairs Bonding pairs Lone pairs Diagram Bond angle / 0 Name 4 0 109.5 Tetrahedral 3 1 107 Pyramidal 2 2 105 Non-linear
Multiple bonds behave like single bonds Bonds Lone pairs Diagram Bond angle / 0 Name 2 0 180 Linear 3 0 120 Trigonal planar 2 1 118 Non-linear
DEFINITION The electrostatic attraction between positive metal ions and their delocalised valency electrons
Positive metal ions Sea of delocalised electrons
Atoms achieve a noble gas or other stable electronic configuration by ionising Metals have giant lattice structures They conduct electricity as their delocalised electrons can move
Strength of metallic bonding depends on Size of ionic charge Number of delocalised electrons Size of ion (ionic radius)
Melting point increases from Na to Al Size of ionic charge increases Number of delocalised electrons increases Size of ion (ionic radius) decreases
Melting point decreases from Li to Cs Size of ionic charge stays the same Number of delocalised electrons stays the same Size of ion (ionic radius) increases When the electrons are further from the centres of positive charge in the ions, the electrostatic forces of attraction are weaker
DEFINITION The ability of an atom to attract the bonding electrons of a covalent bond The most electronegative element is fluorine
Electronegativity increases on crossing a period from left to right Nuclear charge (number of protons) increases Atomic radius decreases Shielding remains constant Thus it becomes easier to attract the electrons of the bond
Electronegativity decreases on descending a group Nuclear charge (number of protons) increases Atomic radius increases Shielding increases Thus it becomes more difficult to attract the electrons of the bond
DEFINITION A shared pair of electrons between atoms with different electronegativities
The more electronegative atom attracts the electrons and becomes a bit negative The other atom is left a bit positive Molecules have a permanent dipole (two poles) H Cl
- Cl Cl - C + Cl - Cl - CCl 4 has four polar covalent bonds The molecules are not polar The polar bonds cancel out each other s effects
+ H N - H + H + NH 3 and H 2 O have polar covalent bonds The molecules are also polar + H O - H + The polar bonds do not cancel out each other s effects
Exist between covalent molecules Are much weaker than covalent bonds Are easily overcome by heat
There are three types of intermolecular bond Van der Waals forces the weakest Permanent dipole / permanent dipole interactions Hydrogen bonds the strongest
DESCRIPTION Electrostatic forces of attraction between molecules or atoms in which the movement of electrons around the nuclei produces temporary induced dipoles
Movement of electrons in one atom causes a temporary dipole This dipole induces another dipole in a nearby atom There is weak attraction between the dipoles Bigger molecules have more temporary induced dipoles, stronger van der Waals forces and higher boiling points
Boiling point increases from Cl 2 to I 2 Size of molecules increases Number of electrons increases More temporary induced dipoles occur Strength of van der Waals forces increases
DESCRIPTION Electrostatic forces of attraction between the oppositely charged ends of molecules with permanent dipoles weak force of attraction H Cl H Cl
These are in addition to van der Waals forces They are stronger than van der Waals forces, need more energy to overcome so molecules have slightly higher boiling points
Occur between molecules where N, O or F are joined to H N, O and F are more electronegative than H and attract the electrons of the bonds to H making it electron deficient + The highly electronegative atom donates its lone pair of electrons to form a bond to an electron deficient hydrogen atom in an adjacent molecule.
O H H Hydrogen bond O H H
These are in addition to van der Waals forces They are much stronger than van der Waals forces so molecules have much higher boiling points Water has abnormally high melting and boiling points due to hydrogen bonding
Bonding Structure Melting point Boiling point Solubility Conductivity Ionic Giant lattice High due to strong electrostatic forces of attraction between ions in the lattice Dissolves in water The polar water molecules are attracted to the ions in the lattice The solid does not conduct electricity NaCl conducts when molten or dissolved in water as the ions are free to move and carry charge
Bonding Structure Melting point Boiling point Solubility Conductivity Metallic Giant lattice High due to strong electrostatic forces of attraction between positive ions and the delocalised electrons in the lattice Reacts with water The solid conducts electricity as the delocalised electrons are free to move and carry charge
Bonding Structure Melting point Boiling point Solubility Conductivity Covalent Simple molecular Low due to the very weak van der Waals forces of attraction between molecules Reacts with water Does not conduct electricity at all as there are no mobile charged particles
Strong covalent bonds throughout the lattice A tetrahedral arrangement of bonds around each carbon atom Bond angles = 109.5 0
Bonding Structure Melting point Boiling point Hardness Conductivity Covalent Giant lattice High due to strong covalent bonds throughout the lattice Hard The tetrahedral arrangement of atoms enables external forces to be spread evenly throughout the lattice Does not conduct electricity at all as there are no mobile charged particles
A hexagonal layer structure Strong covalent bonds within the layers Bond angles = 120 0 Weak van der Waals forces between the layers
Bonding Structure Melting point Boiling point Hardness Conductivity Covalent Giant lattice High due to strong covalent bonds throughout the lattice Soft Bonding within each layer is strong but there are weak forces of attraction between the layers so they can slide over each other The solid conducts electricity as the delocalised electrons between the layers are free to move and carry charge
Bonding Structure Melting point Boiling point Density Conductivity Covalent Simple molecular Relatively high due to the hydrogen bonds between molecules Hydrogen bonds are the strongest intermolecular bonds Lower than water Ice floats as it has an open crystal lattice in which the simple molecules are held apart by hydrogen bonds In water, molecules pack closer together Does not conduct electricity at all as there are no mobile charged particles