TOPIC 3: GIANT COVALENT COMPOUNDS- Diamond.

HideShow resource information
  • Created by: Phoebe
  • Created on: 07-02-13 09:05

COVALENT BONDING

  • Covalent bonding happens when a non-metal bonds with a metal.
  • Formed when a pair of electrons are shared between two atoms which hold the two electrons together.
  • When the electrons are shared, the outer shells overlap and both atoms now have a full outer shell.


1 of 6

SIMPLE MOLECULAR COVALENT SUBSTANCES

This refers to almost all covalent compounds and molecules.

They are 'simple' because each molecule contains a relatively small, fixed number of bonds.

  • eg: Water (H20) and Glucose (C6 H12 06)

- LOW melting and boiling points.

even though the bonds between the atoms are VERY STRONG, the bonds between the molecules are VERY WEAK. 

so a small amount of energy is needed to break the molecules.

2 of 6

GIANT COVALENT COMPOUNDS- Diamond.

  • Every carbon atom is bonded to 4 other carbon atoms in a very ordered way.
  • The strongest substance known to man due to all the strong covalent bonds.
  • Diamond cannot conduct electrcity because all the electrons are fixed in covalent bonds.

(http://www.chemguide.co.uk/atoms/structures/sio2.GIF)

3 of 6

GIANT COVALENT COMPOUNDS- Graphite.

  • Made from carbon (like diamond) 
  • Every carbon atom has one electron NOT involved in bonding in its outer shell.
  • This means these electrons become delocalized over the surface of the sheet. 
  • Means graphite can conduct electricity.
  • High melting and boiling point (strong covalent bonds within layers need a lot of energy to be broken)

(http://www.docbrown.info/page04/4_72bond/graphite.gif)

4 of 6

SEPARATING IMMISCIBLE LIQUIDS

Immiscible liquids: Liquids that don't dissolve in eachother. 

~separating immiscible liquids~

-separating liquids like OIL AND WATER can be easily done with a separating funnel. 

  • let 2 liquids settle on top of eachother. the denser liquid will settle at the bottom. 
  • so the bottom liquid will come out of the funnel first when you open the tap. 
  • when the bottom liquid has come out, quickly shut the tap before the second one does.
5 of 6

SEPARATING MISCIBLE LIQUIDS

We cannot use a separating funnel to separate miscible liquids as they dissolve into eachother when shaken. 

We have to use FRACTIONAL DISTILLATION:

-separates substances by their boiling points.


6 of 6

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Structure and bonding resources »