2 Bonding and structure Flashcards
(27 cards)
Describe “ion”
- a charged atom
- lost or gain at least 1 electron
- can be either positive or negative
- achieving electron stability
Describe “ionic bond”
Transfer of electrons between a metal and a non-metal
Explain “ionic bond”
Strong electrostatic force of attraction between oppositely charged ions
Define “isoelectronic”
Ions that have the same number of electrons
Factors affecting strength of ionic bonds?
- ionic charge
- ionic radius
Properties of ionic compounds?
- giant lattice structure
- high melting point
- conduct electricity when molten or aqueous
- hard and brittle
- only dissolve in polar solvents
Define “electrolysis”
Process of breaking down a substance using electricity
Describe “covalent bond”
Two atoms share at least two electrons where one electron comes from each atom
Explain “covalent bond”
Strong electrostatic force of attraction between the positive nuclei and a pair of shared electrons
Describe “dative/co-ordinate covalent bond”
Two atoms share two electrons, where both electrons come from the same atom
Define “bond length”
The distance between the nuclei of two bonded atoms in a molecule
Define “lone pair”
A pair of electrons that is not involved in bonding
What does the VESPR theory state?
Lone pair-lone pair repulsion is much stronger than lone pair-bond pair repulsion and that lone pair-bond pair repulsion itself is stronger than bond pair-bond pair repulsion.
What does VESPR lead to?
Maximum separation and minimum repulsion between the electron pairs
How is a polar bond formed?
- molecules made up of heteroatoms
- uneven distribution of the shared pairs of electrons
- different nuclear charge of atoms
- difference in the strength of pull
Define “electronegativity”
The measure of an atom’s attraction for a shared pair of electrons in a covalent bond
Why does a polar bond arise?
There is an uneven distribution of electrons due to one atom is more electronegative than the other
Factors affecting electronegativity?
- shielding
- atomic radius
- nuclear charge
What makes a molecule polar?
The molecule has polar bonds and it is not symmetrical so the polarity doesn’t cancel out
What are the 3 types of intermolecular forces?
- London dispersion forces
- permanent dipole-dipole interactions
- hydrogen bonds
Describe “London forces”
- only occur between molecules made of identical atoms or atoms with similar electronegativity values
- very weak
- require very little energy to break
- strength is affected by the number of electrons
Describe “hydrogen bonding”
- only applies to molecules that contain either nitrogen, oxygen or fluorine
- strongest type of intermolecular force
- molecules which show hydrogen bonding also show permanent dipole-dipole interactions
Define “hydrogen bonding”
When a hydrogen atom on one molecule is attracted to more electronegative atom (specifically NOF) on a neighbouring molecule
Define “miscible”
When two liquids mix together
