Covalent Substances Flashcards
Covalent bonding is…
A strong attraction between the bonding pair of electrons and the nuclei of the atoms involved in the bond.
What are substances with simple molecular structures?
Gases, liquids, or solids with low melting points.
Simple molecular substances, melting and boiling points are…
Low, weak intermolecular forces that can be overcome easily.
Giant covalent lattices, melting and boiling points are…
High, strong covalent bonds between the atoms in the lattice that require large amounts of energy to break.
Why does graphite conduct electricity but not diamond?
• Graphite has a free fourth electron on the outer layer of each atom, which can move around, allowing the graphite to conduct electricity (used for electrodes). • None of the electrons are free to move around, because the atoms are tightly held in covalent bonds (used for insulating material).
Why is graphite used for a lubricant and pencil lead but diamond is used for cutting tools and drills?
• Each carbon atom only forms three covalent bonds, creating layers which are free to slide over each other. • Diamond is the hardest material known - there are very strong carbon-carbon covalent bonds which extend throughout the whole crystal in three dimensions. Each carbon atoms forms four covalent bonds in a very rigid structure.
Are the melting points of graphite and diamond high or low?
Both very high. • Graphite has strong bonds within the structure which require lots of energy to break. • Diamond has very strong carbon-carbon covalent bonds, which extend throughout the whole crystal in 3D.
How does a covalent bond form?
A pair of electrons are shared between two atoms. Only between non-metals.
What does the structure of diamond look like?
What does the structure of graphite look like?
