GCSE Chemistry
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- Created on: 01-06-14 11:13
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- GCSE Chemistry
- Atoms
- The random motion of particles is called the Brownian motion. this is caused by particles colliding into each other and their container wall.
- Gas= has no fixed shape or volume and can easily be compressed
- Liquid= can be change shape but not its volume. it also can't be compressed.
- Solid= fixed volume and shape. cannot be compressed.
- Metal atoms (and hydrogen), such as sodium lose electrons to become ions. Ions are charged particles. since metals lose electrons to achieve a full outer shell configuration, the ions have positive charges. a positive charged ion is called a cation.
- Some substances can go from a solid to a gas. this is called sublimation.
- Chemical bonding
- Metal atoms bond with non-metal ions by transferring their electrons. This is called ionic bonding.For some elements, the energy involved in losing or gaining electrons is too much. In these cases their atoms share electrons. this bonding associated with the sharing of electrons is called covalent bonding. there are 4 types of solid, giant ionic, giant covalent, metabolic and simple molecular.
- Sodium chloride is an example of a giant ionic solid. it consists of oppositely charged ions held together by electostatic forces. they are soluble in water and conducts electricity when molten or in solution.
- Dimond and graphite are examples of giant (covalent) molecular solids. they consists of millions of covalent bonds that cause them to have very high boiling points.
- Iodine is an example of simple molecular. it has a low boiling point because molecules of iodine are held together by weak forces. they are insoluble in water and don't conduct electricity.
- Metals consists of tightly packed atoms whose outer electrons become part of a 'sea' of electrons. this delocalisation of electrons explains why metals are good conducters of heat and electricity.
- Non-metal atoms such as chlorine, gain electrons and become ions. by gaining electrons they can achieve a full outer shell. since they gain electrons non-metal ions have negative charges. a negative ion is called an anion
- Atoms are most stable if they have a full outer shell.
- Noble gases do not form compounds. since they already have full outer shells.
- Atoms bond with one another to achieve a full outer shell- this is why most elements form compounds
- Metal atoms bond with non-metal ions by transferring their electrons. This is called ionic bonding.For some elements, the energy involved in losing or gaining electrons is too much. In these cases their atoms share electrons. this bonding associated with the sharing of electrons is called covalent bonding. there are 4 types of solid, giant ionic, giant covalent, metabolic and simple molecular.
- Atoms
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