Bonding and Structure Flashcards
covalent bonding definition
electrostatic attraction between positive nuclei and the shared pair of negative electrons.
list of metallic elements
Li, Be, Na, Mg, Al, K, Ca
list of covalent molecular (diatomic) elements
H2, N2, O2, F2, Cl2
list of discrete covalent molecular elements
P4, S8, C60 (fullerene)
list of covalent network elements
B, C, Si
list of monatomic elements
He, Ne, Ar… (noble gases)
metallic bonding definition
electrostatic attraction between positive metal ions and a sea of delocalised negative outer electrons
London dispersion forces definition
the weak forces between all atoms and molecules including monatomic elements. (weakest form of intermolecular bonding)
strength of LDF
the strength of LDF is related to the number of electrons within an atom or molecule. The more electrons the stronger the LDF will be.
difference between intermolecular and intramolecular forces
intramolecular- within molecules
intermolecular- between molecules
metallic bonding properties
- conduct electricity when solid or liquid due to delocalised electrons.
- high density due to closely packed lattice structure
- usually high bp (lots of bonds to break)
mp and bp of metallic elements trend
- increase across period because more electrons in outer shell, the stronger the metallic bond.
- decrease down a group because the additional filled electron shells weaken electrostatic forces between nuclei and delocalised electrons.
monatomic elements properties
- exist as single atoms
- form no bonds due to full outer shell (no intramolecular bonding)
- do not conduct electricity because there are no free electrons.
- contain LDF
covalent diatomic properties
-low mp/bp because it is the weak intermolecular forces which break between the molecules.
covalent diatomic mp/bp trend
down the group, mp/bp increase because the strength of the LDF is increasing due to larger atoms with more electrons.
Fullerene
- one of the three forms of carbon.
- smallest is C60, known as buckminsterfullerene
- does not conduct electricity as no free electrons.
- NOT A COVALENT NETWORK
- large molecule=strong LDF
covalent network properties
- every atom linked to another by strong covalent bonds
- high mp/bp because lots of energy needed to break strong covalent bonds
covalent network forms of carbon
DIAMOND
-tetrahedral structure
-does not conduct electricity (no free electrons)
-hardest natural substance (used for drills/cutting tools)
GRAPHITE
-layered structure with LDF between layers
-very soft (layers break away due to weak LDF)
-conducts electricity (delocalised electrons)
allotrope
different form of same element
discrete covalent molecular mp/bp
low because it is the weak intermolecular forces which break between molecules not covalent bonds within molecule
noble gases mp trend
increases down the group as larger atoms with more electrons mean stronger LDF.
3 types of Intramolecular bonding
- covalent molecular (polar or non-polar)
- Metallic
- Ionic