Soft copper has a tensile strength of about 200 MPa, a yield strength of 40-80 MPa and an elongation at break of over 40 %. If cold working takes place, the tensile strength increases to at least 350 MPa and the yield strength to at least 320 MPa, but the elongation at break then drops to values below 5 %. Pure copper has no hot-brittle range and can be formed well even in the warm state. At the same time, copper does not become brittle even at low temperatures. Since copper also has considerable fatigue strength characteristics, it is also suitable as a material for oscillating stresses without the fear of brittle fractures. The mechanical properties of the different pure copper grades practically do not differ from each other. Only the creep behaviour can be positively influenced by small additions of alloys such as silver. With alloys, strength values up to approx. 700 MPa, in special cases even up to 1500 MPa, can be achieved, but then the conductivity can decrease considerably.

In its chemical compounds, copper is monovalent and divalent, in some exceptional cases – e.g. in K3[CuF6] – also trivalent, in one case – namely in Cs2(CuF6) – even tetravalent.  In aqueous solutions, copper is the only useful metal that shows a normal potential that is nobler than that of hydrogen. Against acids, the corrosion behaviour of copper depends not only on their type and concentration, but also on the amount of oxygen or an oxidising agent present. Copper is resistant in non-oxidising acids that do not contain dissolved oxygen. Alkaline aqueous solutions of the hydroxides and carbonates of the alkaline earth and alkali metals – with the exception of NH3 – have little effect on copper.

In the atmosphere – also in sea air – copper is very resistant.  Its surface is initially covered with a dark brown to almost black protective layer, which over time usually turns into the green patina familiar from old copper roofs. Patina is a mixture of basic copper salts (sulphate, carbonate, near the sea also chloride), whose quantity ratio is determined by the concentration of the corresponding basic substances in the air. Humid ammonia and hydrogen sulphide vapours have an unfavourable effect. Copper also has good resistance to drinking and industrial water (cold and hot water). It is therefore an excellent material for water pipes. The resistance is linked to the formation of an even protective layer.

Copper is not only a naturally occurring element found in various forms and concentrations in the earth’s crust, oceans, lakes and rivers, but also a trace element essential for life. The life of flora and fauna has developed within the framework of this natural presence of copper. Therefore, most organisms have an intrinsic mechanism for its use. For the human organism, copper has the significance of an essential trace element, i.e. humans need copper in order to survive. Usually, the daily requirement of an adult of approx. 2 milligrams is reached by the intake of a balanced diet with a rich portion of cereals, meat, root vegetables, legumes, nuts or even chocolate. Since copper is particularly important for the metabolism, a copper deficiency can lead to serious health problems.

Copper is the only utility metal that is nobler than hydrogen in the normal voltage series. The good corrosion resistance of copper materials is based on their ability to form stable covering layers that protect the material from further corrosion attack (a visible example of this are the green church roofs). The addition of alloying elements has a positive effect on the formation of the covering layer.

In the atmosphere, these compact and protective layers consist of oxides and hardly soluble basic salts. In solutions, the corrosion behaviour is primarily influenced by the presence of oxygen or other oxidising agents. Depending on the environmental parameters, the medium can be permanently corrosive or lead to the formation of a protective layer. However, an attack of the copper can only take place if the attacking agent contains oxygen or oxidising agents or has an oxidising effect itself, and in weakly attacking agents (e.g. water containing oxygen), the protective layers addressed inhibit or prevent the progression of corrosion.