Water is necessary for life for a wide variety of reasons, these include:
- In the atmosphere, it helps to keep the planet warm
- Our bodies are composed of and dependent on water
The quantum atom
Electrons have no set place of where they can be found, they also have a specific amount (quantum) of energy that is related to their position from the nucleus. Therefore, we can only describe areas of probability where we might find electrons.
Also a quick thing to note is that electric charge is a basic force which causes movement.
Forming a water molecule
There is an unequal attraction to the bonding electrons. This is because oxygen had high electronegativity - therefore it wants electrons more strongly. Hydrogen's electron cloud tends to hang close to oxygen and this leaves hydrogen's positively charged nucleus all by itself.
δ is the symbol for delta - this means slightly.
Dipole means that there are two charges.
As the electron density of water is uneven, this leads to a dipole and it also makes water a polar molecule. This is because one end is more positive than the other.
Properties
- Universal solvent
- Exists in nature as a solid, liquid and gas naturally
- The density of ice is less than liquid water
- High surface tension
- High heat capacity
- Exists as a liquid at room temperature
Properties explained -
Water is a polar molecule; this allows it to dissolve nearly any substance with an unequal distribution of charge. It also dissolves more substances than any other liquid.
The only substances which it cannot dissolve is truly non-polar substances such as oil and hydrocarbons. It is also the best substance that is universally used for transporting dissolved substances.
High surface tension allows water to form drops and waves. Water can 'adhere' to surfaces even though gravity is pulling on them.
Adhesive forces are attractive forces that occur between two unlike substances. This means that when water is in a tube, it is more strongly attracted to the tube than to themself (this is called cohesion).
This is useful for evapotranspiration - tiny tubes in the roots suck up water, the xylem transports water through the plant and finally water exits the plant through stomata.
Specific heat capacity is the amount of energy required to change 1 gram of substance by 1℃. Water has a high specific heat capacity - this is because it has to absorb large amounts of heat energy before it begins to get hot, it also releases heat energy slowly.
Water helps to moderate the climate and helps living organisms regulate their body temperature.
It also forms a crystal lattice when it freezes, this makes ice less dense than water. Ice has an open lattice structure that collapses when it melts.
Inorganic ions
Inorganic ions are charged atoms that do not contain carbon - for example: iron, hydrogen, sodium and phosphate
Iron
- The chemical symbol is Fe
- It produces 2+ and 3+ ions
- It is part of haemoglobin - a quaternary globular protein
- 4 polypeptide chains
- haem group (Fe 2+)
- Oxygen binds to this group
- Oxyhaemoglobin contain Fe 3+ (oxygen and haemoglobin)
Hydrogen
- Forms a H+
- The more H+ ions, the more acidic the solution (lower pH)
- Enzymes will become denatured at low/high pH
Sodium
- Forms Na+ ion
- It is used in co-transport, to assist the movement of glucose and amino acids across the cell membrane
Phosphate
- Forms a PO4 3- ion
- It is found in DNA, RNA, ATP and phospholipids
- In ATP, phosphate groups store the energy
- It makes up the hydrophilic head of phospholipids in cell membranes
- DNA/RNA allow nucleotides to join together through phosphodiester bonds