PHYSICAL - BONDING Flashcards
Describe ionic bonding and the factors that affect it
Metal and non -metal
Involves electrostatic attraction between oppositely charged ions in a lattice.
FACTORS = smaller ion (stronger attraction) and higher charge
Define metallic bonding and its arrangement
electrostatic force of attraction between the positive metal ions and the delocalised electrons.
- arranged in a lattice
What are the factors that affect the strength of metallic bonding
number of protons
number of delocalised electrons
size of ion (smaller the ion the stronger the bond)
What are the types of covalent bond?
SINGLE (contains a shared pair of electrons)
MULTIPLE ( contains multiple pairs of electrons)
CO ORDINATE (contains a shared
pair of electrons with both electrons supplied by one atom) - uses an arrow
How does a co-ordinate bond form?
When one atom has a lone pair of electrons that can be donated to an atom with a vacant orbital
Which elements can expand their octet?
Aluminium Silicon Phosphorous Sulfur Chlorine Argon
What is electronegativity?
The ability of an atom to attract the pairs of electron in a covalent bond.
It is based on the attraction of an electron pair and the nucleus of an atom
3 factors that affect electronegativity
- Size of the positive charge of the nucleus
- Atomic radius
- Shielding of nucleus
What is a dipole?
A molecule or covalent bond that has a separation of charges
How do dipoles occur?
When electrons are shared unequally between atoms in the same molecule due to a high difference in the electronegativity of the atoms involved
What are two ways you can show a bond is polar
d+ and d-
Or an arrow with the head pointing towards more electronegative
What does symmetrical mean
When the atoms are being pulled in the same direction
Describe Van der Waals force
It is the weakest force and acts as an induced dipole between anything with electrons and creates temporary dipoles.
What affects the strength of a van der waals force
- Larger Mr means stronger IMF
- Straight chain molecules experience stronger Van der Waals than branched chain molecules as they can line up and pack closer together which in turn reduces distance over which the force acts over and is therefore stronger.
Van der waals melting and boiling point.
Boiling : The stronger the Van der Waals forces, the higher the boiling point
Melting : low melting points due to being a weak intermolecular force
Describe a dipole-dipole force
Acts between molecules within a polar bond
The d+ and d- regions attract each other and hold the molecules together in a lattice like structure
When do hydrogen bonds form
Forms between a hydrogen and a very electronegative atom (flourine, nitrogen and oxygen)
Electronegative atom must have a lone pair of electrons as these will be attracted to the partially charged hydrogen atom in another molecule and form the charge
Represented with a dashed line
Hydrogen bonding melting and boiling points
Raises both melting and boiling points
- because h bonds are strong imf that create stable molecules and it takes more energy to break up to molecule than it would if the bond wasn’t there
