Ionic and Covalent Bonds Flashcards
What are ionic bonds?
Strong electrostatic forces of attraction between oppositely charged ions
Explain why ionic compound cannot conduct electricity
The ions aren’t free to move (unless molten)
Why do ionic compounds have high melting and boiling points?
The ionic bonds are very strong
What are covalent bonds?
Strong bonds between non-metal atoms, formed when a pair of electrons are shared
How can you model a covalent bond?
By drawing a dot and cross diagram
What do atoms that are covalently bonded together form?
A molecule (which can be elements or compounds)
What is a simple molecule? What are the melting and boiling points like?
A simple molecule consists of a few atoms joined together by strong covalent bonds. The intermolecular forces are weak, so the mps and bps are low
Why don’t simple molecular substances conduct electricity?
Their molecules aren’t electrically charged, and they don’t contain electrons that are free to move
(unless molten)
Why aren’t simple molecular substances soluble in water?
The intermolecular forces between the water and these substances are weaker than the forces between the water molecule and the forces between the molecules in the substance itself
What is a giant molecular substance?
Many atoms joined together by strong covalent bonds, arranged in a giant lattice structure. High mp and bp.
Explain why graphite conducts electricity but diamond doesn’t.
A carbon atom can form four covalent bonds. Graphite only forms three, so there are delocalised electrons which move through the structure.
Diamond has four covalent bonds per atom, so it has no delocalised electrons
What can graphite and diamond be used for?
Diamond can be used for cutting tools - rigid lattice structure and strong bonds makes it very hard.
Graphite can be used as a lubricant - weak intermolecular forces allow layers to slide over each other
