Structure and bonding (3) Flashcards
Ionic bond definition
The strong electrostatic force of attraction between the positive ion and the negative ion.
Ionic structure
Lattice
What does an ionic formula do
It shows the simplest ratio of ions and the charges of the ions
Covalent bond definition
The electrostatic force of attraction between the positive nuclei and the shared electrons.
Pure covalent bond definition
Where the atoms involved in the covalent bond have the same Electronegativity, or less than 0.5 difference, and therefore share the electrons equally and no dipole is formed.
Polar covalent bond definition
Where atoms of a covalent bond have a difference in electro negativity of between 0.5 and 1.6 meaning electrons are shared inequally and this causes a permanent dipole
Dipole definition
When atoms share electrons inequally due to the difference in Electronegativity of 0.5 or more, therefore causing the atoms to become oppositely charged.
What is the bonding continuum
The order of intramolecular bonds between atoms in order of lowest Electronegativity to highest Electronegativity.
Bonding continuum of pure covalent
Both non metals and less than 0.5 difference
Polar covalent continuum
0.5 to 1.6 and both non metals
Ionic bond continuum
More than 1.6 between a metal and non metal , more than 2.0 between non metals .
Covalent molecule melting and boiling point
Low
Ionic bond melting and boiling point
High
Electrical conductivity ionic bond
Conduct in liquid/solution
Electrical conductor covalent bond
No
van der Waals forces
Intermolecular forces
Intramolecular forces examples
Pure covalent bond
Polar covalent bond
Ionic bond
Types of van der Waals
London dispersion forces
Permanent dipole - permanent dipole
Hydrogen bonding
London dispersion forces definition
The intermolecular force of attraction between atoms or molecules due to a temporary and induced dipole, caused by the movement of electrons and unequal distribution of electrons.
London dispersion forces rules
The more electrons the stronger the LDF’s are
The larger the molecule the stronger the LDF’s are
What type of molecules and atoms have London dispersion forces
All that have electrons
Permanent dipole - permanent dipole definition
The intermolecular force of attraction between polar molecules oppositely charged dipole. (Not on the same molecule)
Polar molecules definition
An unsymmetrical molecule containing a dipole.
Hydrogen bonding definition
The intermolecular force of attraction between the small hydrogen atom and an atom of high Electronegativity such as oxygen nitrogen or fluorine. (Not within the same molecule)
Hydrogen bonding atoms
Nitrogen, oxygen and fluorine
Hydrogen bonding rules
The hydrogen must be directly bonded to the other atom
The more examples of hydrogen bonding in the molecule the stronger the hydrogen bonding.
van der Waals strength scale
Hydrogen bonding
Permanent dipole - permanent dipole
London dispersion forces
Why is water denser than ice
Because when water freezes the strong hydrogen bonds create a spacious hexagonal structure, whereas in water the molecules are pulled very closer together.
What do polar substances dissolve in
Polar solvents
What do non polar substances dissolve in
Non polar solvents
What do ionic substances dissolve in
Polar solvents
What do hydrogen bonded substances dissolve in
Hydrogen bonded solvents
How do ionic substances dissolve
The polar solvents will break apart the lattice and surround their oppositely charged ion.
Viscosity rule
The stronger the intermolecular forces, the stronger the viscosity
Polar experiments
Put the solvent next to a charged rod and see if it bends
Viscosity experiments
See how long an air bubble travels to the bottom of the tube with the liquid in.
Unique feature of water
Surface tension
(Hydrogen bonding)
