Chemistry 2 - bonding, structures and properties Of Matter

Question 1

Ions

Answer 1

Ions are charged particles

Made when electrons are transferred

Metals form ions they lose electrons
Non-metals form ions they gain electrons

The number of electrons lost equals the charge of the ion E.g. if 2 electrons lost charge would be 2+

Question 2

Ionic bond - transfer of electrons

Answer 2

When a metal and non-metal react together, the metal atom loses electrons to form a positively charged ion and the non-metal gains these electrons becoming a negative ion. These oppositely charged ions are strongly attracted to one another by electrostatic forces. This attraction is called an ionic bond.

Question 3

Covalent Bonds - non-metal and non-metal

Answer 3

When non-metals bond together they share pairs of electrons to make covalent bonds

The positive charged nuclei of the bonded atoms are strongly attracted to the shared pairs of electrons by electrostatic forces making them very strong

Each single covalent bond provides one extra shared electron

Question 4

Polymers

Answer 4

Polymers are lots of small units linked together to form a long molecule that has repeating sections

All atoms in a polymer are joined by strong covalent bonds

Most polymers are solid at room temperature( larger intermolecular forces than simple covalent molecules)

Lower boiling points than ionic or giant molecular compounds

Question 5

Macromolecules - giant covalent structures

Answer 5

All atoms bonded to each other by strong covalent bonds

Diamond - each carbon atom forms four covalent bonds in a very rigid giant covalent structure

Graphite - each carbon atom forms three covalent bonds to create layers of hexagons. Each carbon atom also has one delocalised electron (so can conduct electricity and thermal energy)
Also a lubricating material ( no covalent bonds between layers therefore free to move over each other)

Question 6

Metallic bonding - metal and metal

Answer 6

Consist of giant structure

Electrons in outer shell are delocalised

Strong forces of electrostatic attraction between positive metal ions and the negative electrons

Forces of attraction hold the atoms in a regular structure

Solid at room temperature

Electrostatic forces very strong - needs a lot of energy to be broken meaning very high melting & boiling points

Good conductors of electricity and heat

Malleable - layers of atoms can slide over each other

Alloys - mixture of metals to make them harder - different sized atoms distort the layers

Question 7

Nano particles

Answer 7

Coarse particles - have a diameter between 2500nm and 10,000nm

Fine particles - have a diameter between 100nm and 2500nm

Nano particles - have a diameter between 1nm and 100nm

Surface area to volume ratio = surface area / volume

Uses:
Help make new catalysts
Used in tiny electric circuits 
Antibacterial properties ( silver nanoparticles)
Cosmetics 
Sun creams