Chemical Bonding Flashcards
Ionic bonding
The electrostatic attraction between oppositely charged ions
Giant ionic lattice
A three dimensional structure of oppositely charged ions held together by ionic bonds
Properties of ionic compounds
- High melting point and boiling point as ionic bonds are strong and have to all be broken to change states
- Conducts electricity when molten or aqueous as ions are free to move to carry charge
- Dissolves in polar substances. Six O- rip off a cation while 4 H+ rip off the anion
- Don’t dissolve in non-polar solvents
- Don’t conduct electricity as a solid
- Tend to be brittle as when the layers shift, the opposite ions will repel
Isoelectronic
To have the same number of electrons e.g. Si4+ is isoelectronic with Ne
Covalent bond
The electrostatic attraction between two nuclei and the same shared pair of electrons
Lone pair
An outer shell pair of electrons that is not involved in chemical bonding
The octet rule
The rule that only 8 electrons occupy one shell when bonding with other atoms
Dative covalent bond
A covalent bond formed when a lone pair has been provided by one of the bonding atoms
Properties of diamond
- Doesn’t conduct electricity as there are no free charge carriers available
- Giant covalent lattice
- Tetrahedral C arrangement
- Bare hard as covalent bonds are strong and a lot of energy is needed to break them all
Properties of graphite
- Giant covalent structure
- Conducts electricity as there is a layer of delocalised electrons between the C layers that can carry charge
- C arranged in layers
- Layers can slide over each other so graphite can acts as a lubricant
Allotrope
Refers to one or more forms of an elementary substance
Metallic bonding
The electrostatic attraction between cations and a sea of delocalised electrons
Properties of metals
- High melting and boiling points as there is a large electrostatic attraction between the cations and the delocalised electrons
- Good conductors as delocalised electrons can carry charge
- Even better conductors when molten as the cations can carry charge too
- Insoluble in water or non-polar substances as the metallic bonds are too strong relative to intermolecular forces
- Malleable
- Ductile
Trend in mp/bp of metals (I,II,III)
- Increases along the group as the number of electrons are increasing and the charge on the cations are too
- Decreases down a group as the outer electron is far from the nucleus and can be removed easily
Malleability
The ability to change shape without breaking
Ductility
The ability to be pulled into a thin wire