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101: Leaching / Eutrophication
Leaching describes the "washing out" from soils any soluble chemicals that are not "bound" to the soil particles. It occurs as excess rain (or flood) waters drain through the soil...

102: Pollution
The impact of human activities on the earth has become noticeable and significant during the last century resulting from: Increasing population - this resulted from increased food supply and improved..

103: Diffusion
Diffusion is the seemingly random movement of a substance from where these particles are in high concentration to where there are fewer. The diffusion stops where there is no concentration gradient ex..

104: Genetic Terminology
DNA The molecule which contains genes. It's shaped like a double helix (a spiral) Chromosomes Found in the cell nucleus: X-shaped things made up of long coils of DNA ..

105: Cells / Tissues / Organs
Protoplasm Consists of cytoplasm and nucleus. Cytoplasm Jelly like substance where chemical reactions take place and other parts are embedded. Nucleus ..

106: Classification of Living Things
Living things are grouped into 1 of 5 kingdoms which are as follows: Animals, Plants, Fungi, Protista, and Monera. The list below shows the other attributes (in order) which are used to more accuratel..

107: Life Processes
Movement Animals move to find food and away from predators and plants move towards light. Reproduction Both animals and plants reproduce to keep their spec..

108: Mitosis
Between divisions, a copy of each chromosome is made. The chromosomes then start to become visible. The centrioles separate and move to opposite poles (ends) of the cell. The chromosomes are clearly v..

109: Meiosis
As meiosis begins, the chromosomes start to become visible. At this stage they have produced replicas of each other. The centrioles separate and move to opposite poles (ends) of the cell. The chromoso..

110: Alcohol
Alcohols make good fuels because they burn easily and they release a lot of heat energy, which can be harnessed to power machines etc... The combustion of alcohol is an exothermic reaction and this me..

111: Fractional Distillation
Fractional distillation is the process of heating up a mixture containing different substances with different boiling points, and drawing the different fractions off as they each boil and liquify at i..

112: Alkenes
The general formula for alkenes is as follows: CnH2n   (where "n" is a constant) Alkenes are unsaturated hydrocarbons because they contain a double bond between two of their carbon..

113: Alkanes
The general formula for alkanes is as follows: CnH2n+2   (where "n" is a constant) The first ten members of the homologous series of the alkanes are: CH4     (Metha..

114: Organic Chemicals
Organic chemistry is the study of carbon compounds. The number of different organic compounds which are known is well over 1 million and these compounds vary in properties, economic importance and us..

115: Carbon Cycle
The carbon cycle is simply the process by which Carbon Dioxide is put into and removed from the atmosphere. This process is very finely balanced to keep the percentage of CO2 in the atmosphere at 0.03..

116: Water Purification
There are 3 main processes undertaken in the water purifying process: Filtration Bacterial Oxidation Chlorine Treatment The different stages are listed in more detail below: Water pumped f..

117: Water Softening
Temporary Hard Water This is caused by calcium or magnesium hydrogen-carbonate. It can be removed by boiling the water. Ca(HCO3)2 (aqueous)   ---->   CaCO3 (solid)   +   H2..

118: Scum Formation
Soap contains salts such as sodium stearate and sodium palmitate and when calcium ions in hard water mix with soap, a precipitate of calcium stearate / calcium palmitate is formed. In the following eq..

119: Hard Water
Hard water does not produce as much lather as soft water when it is used with soap and also an insoluble solid called scum is left on the sides of the wash basin. Calcium chloride, Magnesium nitrate, ..

120: Chemical Changes
Thermal Decomposition A single substance is broken down by heating. A good example of this is the cracking of hydrocarbons. Displacement When one more reactive element pushes another less reactive el..

121: Electrolysis
This is the (chemical) process by which a compound in its molten state is decomposed to form its elements. Some of its uses are as follows: Extraction of reactive metals from their ore. (e.g. - alumin..

122: Ion Analysis
Testing for Cations Cations are positively charged (+) ions. There are 2 basic tests for them: Flame test Adding NaOH (aq) to solution of ionic compound The flame test involves a clean nichrome ..

123: Bonding
Metallic Bonding This occurs in metals and is when electrons are given out from the metal atoms to make a "sea" of free electrons in between all of the metal atoms. These free electrons hol..

124: Important Ions
The table below lists some important ions that you should really know about: Name of Ion Formula Hydroxide OH (-) Carbonate CO3 (-2) ..

125: Reactivity Series
The following list shows how reactive different elements are in relation to each other. This is a shortened list but contains most of the elements that you need to know about. Potassium    ..


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