Bonding, Structure And Properties Of Matter Flashcards
What are ions?
They are charged particles - they can be single atoms (Cl-)or groups of atoms (NO-3)
What groups are most likely to form ions?
Groups 1, 2, 6, and 7
- groups 1 and 2 lose electrons to form positive ions (cations)
- groups 6 and 7 gain electrons to form negative ions
Ionic bonding - transfer if electrons
When a metal and non-metal react together, the metal atom loses electrons to form a positively charged ion ant the non-metal atom gains these electrons to form a negatively charged ion.
What is the structure of Ionic compounds called?
Giant ionic lattice. The ions form a closely packed regular lattice arrangement and there are very strong electrostatic forces of attraction between oppositely charged ions, in all directions in the lattice
Ionic compound similar properties
- they all have high melting and boiling points
- cannot conduct electricity when they are solid but can when they melt
- dissolve easily in water
Covalent bonds - sharing electrons
- when non-metal atoms bond together, they share pairs of electrons to make covalent bonds
- the positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces, making the bonds very strong
- atoms only share electrons in their outer shell
What are simple molecular substances made up of?
Made up of molecules containing a few atoms joined together by covalent bonds
Properties of simple molecular substances
- held by very strong covalent bonds
- to melt or boils a s.m compound, you only need to break these feeble intermolecular forces and not the covalent bonds.
- very low melting and boiling points
- most are gases or liquids at room temp.
- don’t conduct electricity
Polymers
- Lots of small units are linked together to form a long molecule that has repeating sections.
- joined by strong covalent bonds
Giant covalent structures
- all the atoms are bonded to each other by strong covalent bonds
- very high melting and boiling points
- don’t conduct electricity
- main ones are diamond, graphine/graphite and fullerene
Diamond
- made up of carbon atoms that each form 4 covalent bonds.
- really hard
- very high melting point
- does not conduct electricity
Graphite
- forms 3 covalent bonds, creating sheets of carbon atoms arranged in hexagons
- aren’t any c.b between the layers
- held together weakly, so they’re free to move over each other making them soft and slippery
- high melting point
- each carbon atom has one electron that is delocalised and can move. This means it can conduct electricity
- graphine is one sheet of graphite
Metallic bonding involves delocalised electrons
- metals also consist of a giant structure
- strong forces of electrostatic attraction
- these forces hold the atoms together in a regular structure and are known as metallic bonding
- it’s the delocalised electrons which produce all the properties of metals
Most metals are solid at room temp.
- very strong
- high melting and boiling points
- conduct electricity
- malleable (can be bent into flat sheets)
States of matter
Solid, liquid and gas
