Gruping Living Things

Living things are organized by scientists into five groups called kingdoms, of which the animal kingdom is one. The common and scientific names of these are: Animals (Animalia); Algae and protozoan’s (protoctista); Bacteria (Prokaryotae); Mushrooms, moulds and lichens (Fungi); plants (Plantae).
The animal kingdom alone has thousands of different species. A species is a type of animal, and animals of the same species can breed successfully with each other. Similar species are grouped in a genus. Genera are grouped into families, families into orders, right up to the level of phylum. The phylum chordate contains all vertebrate animals- animals with a backbone.

Elements on Earth

There is calcium in the Earth and sea in the form of calcium carbonate. Sodium exists in the form of sodium chloride, the salt in sea and on our tables. The quantities of both calcium and sodium are so vast that these elements are considered unlimited. Some elements are mined and used in industry. Iron is the most common, followed by magnesium.
There are quite small amounts of some precious metals on Earth, which is why they are so valuable. For example, there are about one million tonnes of silver and 15,000 tonnes of gold. Elements are constantly being taken from Earth, but new discoveries are being made. We are still some way from returning out of even the rarest animals.
Some of the heaviest elements in Earth are Osmium, Platinum, Plutonium and Gold. The lightest elements in Earth are Hydrogen, Helium, Lithium, Potassium and Sodium. Each and every element has its own characteristics.