2: Covalent Bonding Flashcards
1
Q
Central atoms
A
- Lowest subscript in formula
- Most bonding e- and/or least electronegative atom (apart from Hydrogen)
2
Q
Lone pairs
A
- e- pairs not involved in covalent bonding
3
Q
A
4
Q
Polar bonds
A
- Two bonded atoms have DIFFERENT electronegativities
The electron pair orbits CLOSER TO THE ATOM WITH THE GREATER ELECTRONEGATIVITY - This causes a ‘permanent dipole’
5
Q
Non polar bonds
A
Constituent elements have similar electronegativities
6
Q
How to tell if element is polar
A
- Molecule is ASSYMETRICAL
- Molecule has COVALENT BONDING
7
Q
Three intermolecular forces
A
- Hydrogen bonding (strongest)
- Dipole-Dipole
- Dispersion forces (weakest)
8
Q
What do the strength of intermolecular forces determine?
A
- melting point
- states of matter
- boiling point
9
Q
Dispersion forces
A
‘Momentary force of attraction between instantaneous dipole and induced dipole’
- Between all molecules
10
Q
Dipole - Dipole interactions
A
‘**Attraction between the + and - poles of molecules’ **
- The stronger the electronegativity difference between constituent elements of the molecules, the stronger the dipole - dipole interactions will be
11
Q
Hydrogen bonding
A
‘Special type of dipole-dipole interaction’
- When partially positive Hydrogen atoms are attracted to partially negative Fluorine/Nitrogen/Oxygen in another molecule
12
Q
Properties of covalent substances
A
- Have lower m/p/b.p compared to metals and ionic compounds
- M.p/b.p increases with stronger intermolecular forces
- Not electrical conductors (Don’t have free flowing charged particles)
- Polar molecules are soluble in polar solvents
- Non polar molecules are soluble in non polar solvents
13
Q
Diamond
A
Covalent network lattice
- Each carbon surrounded by 4 other C atoms in 3D tetrahedral lattice
14
Q
Graphite
A
Covalent layer lattice
- Each carbon bonded to 3 other C atoms, one delocalised electron per C atom
15
Q
Diamond properties
A
Hard
Brittle
Non-conductive of electricity
16
Q
Graphite properties
A
Conductive of electricity
Slippery
Soft
17
Q
Diamond uses
A
Drill bits
Jewllery
18
Q
Graphite uses
A
Industrial lubricant
Pencils
Electrodes
19
Q
A
