Basic Ideas
Key Terms
- Atom - The smallest particle of an element, with no overall charge
- Molecule - At least two atoms joined in a covalent bond with at least two shared electrons, like H2O
- Element - The most basic unit of a pure substance, made of atoms of one type only
- Compound - A chemical substance of at least two chemically bonded elements
- Organic - A member of a class of chemical with molecules containing carbon
- Inorganic - A molecule that does not contain carbon, although there are a few molecules that contain carbon that also qualify
Essential Elements
- C - Carbon
- H - Hydrogen
- O - Oxygen
- N - Nitrogen
Between them, these make up about 99% of the atoms in living organisms.
Carbon is absolutely crucial cut to it's ability to make four covalent bonds.
Trace Elements
Some elements are only needed in small amounts, usually as inorganic ions.
- Ca2+ - Calcuim - Needed by bones and teeth, and for blood clotting
- Fe2+ - Iron - Found in Haemoglobin
- Cl- - Chlorine - Controls blood pH
- Mg+ - Magnesium - Essential to bones
Important Compounds
These four compounds will be looked at in more detail in the following sections;
- Water
- Protein
- Carbohydrate
- Lipids
Comments
- Written for: WJEC New Spec AS Biology By1, Topic 1
- Started by: MatthewHiggins-424291 11:05, 10 April 2010 (BST).
- I will finish it very soon!
