Chemical bonding Flashcards
Covalent bonding
The sharing of electrons between 2 atoms
Molecule
A group of atoms joined together
Bonding pair
Shared electron pairs that form a covalent bond
Lone pair
Electrons not involved in bonding
Sigma bond
The head on overlap of 2 s orbitals
Pi bond
The sideways overlap of 2 p-orbitals
Compound
A substance that is made up of 2 or more elements chemically combined
Ionic bond
The force of attraction between oppositely charged ions in a compound.
They are formed by the complete transfer of electrons from one atom to another
How many electrons in shell
2 , 8 , 18
Single bond
One sigma bond
Double bond
One sigma + one pi bond
Triple bond
One sigma + 2 pi bond
Ionic properties
Hard + brittle
Usually solid at room temp
High boiling and melting points
Covalent properties
Usually soft solids , gas or liquid at room temp
Low melting and boiling points
Soft
VSEPR
Valence Shell Electron Pair Repulsion
Non polar covalent bonds
When atoms in a molecule equally share electrons (no charge)
Polar covalent bond
When the atoms in a molecule unequally share electrons (one side is slightly positive and the other side is slightly negative)
Intramolecular forces
Bonding that takes place within the molecule eg covalent bonding
Intermolecular forces
Bonding takes place between molecules. Eg van der waals , dipole-dipole and hydrogen forces
Van der waals forces
Definition= weak attractive force between molecules resulting in temp dipoles
ONLY OCCUR WITH NON POLAR MOLECULES
Weakest = lowest boiling point
Dipole-Dipole
Definition= the force of attraction between the negative pole of a polar molecule and the positive part of another pole molecule.
Medium strength = average boiling points
ONLY OCCURS FOR POLAR COVALENT SUBSTANCES
Hydrogen bonding
Definition= particular dipole-dipole attractions between the molecule which hydrogen is bonded to N,O,F
Strongest= highest melting point
ONLY OCCURS FOR N , O , F
Dissolving compounds in water
LIKE DISSOLVES IN LIKE
(Polar dissolves in polar)
Water is highly polar so it dissolves with polar and ionic compounds
Valency
The number of atoms of hydrogen that an element will bond with
