3.1.3 Bonding Flashcards
Ionic Bonding [definition]:
The electrostatic attraction between oppositely charged ions in a lattice
Covalent Bonding [definition]:
A shared pair of e⁻s with opposite spins
- one e⁻ donated by each atom
Sulphate formula:
SO₄²-
Hydroxide formula:
OH−
Nitrate formula:
NO₃⁻
Giant Ionic lattice [2]:
- Sodium Chloride
- Magnesium oxide
Covalent simple molecular structures [5]:
- Iodine
- Ice
- Carbon dioxide
- Water
- Methane
Giant Covalent structures [4]:
- Diamond
- Graphite
- Silicon dioxide
- Silicon
Ionic boiling and melting points [2]:
- high- because of giant lattice of ions with strong
electrostatic forces between oppositely charged ions - requires lot of energy to break
Ionic Solubility in water:
Generally good
Ionic compound conductivity (when solid):
[2]
- poor
- ions can’t move/ fixed in lattice
Ionic compound conductivity (when molten):
[2]
- Good
- Ions can move freely
Co-ordinate/ Dative Covalent bond [definition]:
A bond that contains a shared pair of electrons with both electrons supplied by one atom.
Simple Covalent compound boiling and melting points:
low- because of weak intermolecular forces between molecules (specify type e.g van der
waals/hydrogen bond)
Simple covalent compound solubility in water:
Generally poor
Simple covalent compound conductivity (when solid):
[2]
- poor
- no ions to conduct and electrons are
localised (fixed in place)
Simple covalent compound conductivity (when molten):
[2]:
- Poor
- No ions
Giant Covalent compound boiling and melting points:
High- because of many strong covalent
bonds in macromolecular structure (requires a lot of energy to break many strong bonds)
Giant covalent compound solubility in water:
Insoluble
Giant covalent compound conductivity (when solid):
[2]:
- diamond and sand = poor because electrons are localised and can’t move
- graphite = good, has free delocalised electrons between layers to conduct
Giant covalent compound conductivity (when molten):
Poor
Metallic bonding boiling and melting points:
high- strong electrostatic forces between positive ions and sea of delocalised electrons
Metallic bonding solubility in water:
Insoluble
Metallic bonding conductivity (when solid):
[2]:
- good
- delocalised electrons can move through structure
Metallic bonding conductivity (when molten):
Good
Linear Shape [3]:
- BP:2
- LP: 0
- Bond angle: 180
Trigonal Planar Shape [3]:
- BP: 3
- LP: 0
- Bond angle: 120
Tetrahedral Shape [3]:
- BP: 4
- LP: 0
- Bond angle: 109.5
Bent Shape [3]:
- BP: 2
- LP: 2
- Bond angle: 104.5
Trigonal Pyramidal Shape [3]:
- BP: 3
- LP: 1
- Bond angle: 107
Trigonal Bipyramidal Shape [3]:
- BP: 5
- LP: 0
- Bond angle: 120 and 90
Octahedral Shape [3]:
- BP: 6
- LP: 0
- Bond angle: 90
Electronegativity [definition]:
Electronegativity is the relative tendency of an atom in a covalent bond to attract electrons in a covalent bond to itself
What are the most electronegative atoms? [3]:
- Fluorine
- Oxygen
- Nitrogen
[F, O, N]
Factors affecting electronegativity [2]:
- increases across a period as the number of protons increases and the atomic radius decreases cus electrons in the same shell are pulled in more
- decreases down a group cus the distance between nucleus and outer electrons increases + shielding of inner shell electrons increases
Purely covalent compound [definition]:
A compound containing elements of similar electronegativity and hence a small electronegativity difference will be purely covalent
Ionic compound [definition]:
A compound containing elements of very different electronegativity and hence a
very large electronegativity difference (> 1.7) will be ionic
When does a polar covalent bond form?
when the elements in the bond have different
electronegativities. (Of around 0.3 to 1.7)
What is a polar covalent bond?
When a bond is a polar covalent bond it has an unequal distribution of electrons in the bond and produces a charge separation, (dipole) δ+ δ- ends.
Symmetrical molecule [3]:
- All bonds identical
- No lone pairs
- Will not be polar even if individual bonds within the molecule are polar
(The individual dipoles on the bonds ‘cancel out’ due to the symmetrical shape of the molecule.
There is no NET dipole moment: the molecule is
NON POLAR)
Where do Van der Waal forces occur? [2]:
- Occur between all molecular substances and noble gases
- They do not occur in ionic substances
The main factor affecting the size of Van der Waals [2]:
- The more electrons there are in the molecule the higher the chance that temporary dipoles will form
- This makes the Van der Waals stronger between the molecules and so boiling points will be greater
What is the weakes IMF?
Induced dipole/ Van der Waal’s
When do ions form?
When e⁻s are transferred between elements that have a large diff in negativity (metal + non-metal)
How are ionic lattices structured?
Regular lattice with alternating +ive & -ve ions
What holds an ionic lattice together?
Very strong electrostatic forces