Covalent bonding Flashcards
What is a covalent bond?
Strong electrostatic attraction between a shared pair of electrons and the positive nuclei
What type of elements form covalent bonds?
non-metals
Give the displayed formula of H₂O
H-O-H
Give the displayed formula of O₂
O=O
What is a single covalent bond
single pair
What is a double covalent bond?
two pairs
What is a simple molecular substance?
A simple molecular substance is a covalent molecule made up of just a few atoms
What is the melting point of a simple molecular substance and why?
low because weak intermolecular forces do not require a lot of energy to overcome
What is the conductivity of a simple molecular substance?
do not conduct electricity as no ions or delocalised electrons that can move
What is the solubility of a simple molecular substance?
usually insoluble in water as simple molecules are not attracted to water
What is a Buckminster fullerene?
(C₆₀) simple molecule composed of 60 carbon atoms in a ball
What is the boiling point in a Buckminster fullerene?
600ºC
low compared with giant covalent structures due to weak intermolecular forces which don’t require a lot of energy to overcome
high compared with other simple molecular substances as there are more electrons in the molecule
Why is a Buckminster fullerene soft and slippery?
weak intermolecular forces that can move
What is a giant covalent substance?
Structures containing a large number of non-metal atoms each joined to adjacent atoms by covalent bonds.
Give three examples of giant covalent substances
Diamond (each carbon atom bonded to 4 others), silicon dioxide, graphite (each carbon atom bonded to 3 others)
What type of melting point do giant covalent structures have and why?
High as lots of energy is needed to break strong covalent bonds
What is the conductivity of a giant covalent substance and why?
usually non-conductive as no free ions and delocalised electrons that can move
What are the properties of Diamond and Silicon Dioxide?
Hard - strong covalent bonds require lots of energy to break
High melting point - lots of energy required to break strong covalent bonds
Insoluble
cannot conduct electricity - no free ions and delocalised electrons that can move
Uses of diamond?
diamond tipped drill bits, cutting tools
What are the properties of graphite?
high melting point - lots of energy needed to break strong covalent bonds
soft - layers can slide over each other due weak forces between them
conductive - each carbon atom has a spare electron that is delocalised and can move
Uses of graphite?
pencils
What are the allotropes of carbon?
diamond, graphite, Buckminster fullerene
What is a metallic bond?
a strong electrostatic attraction between positive metal ions and delocalised electrons
What type of melting point do metallic compounds have and why?
high as has strong bonds that require lots of energy to overcome
