Variation in this gain or loss results in ‘variable valency’.ĬuCl is named as cuprous chloride (lower valency)ĬuCl 2 – Cupric chloride (higher valency) has variable valency reason for variable valency Valency is – the number of electrons lost or gained from the outer shell of an atom of an element – during chemical reaction. Variable valency : “When an element has more than one valency, its valency is called variable valency.” Copper exhibit valency ‘1’ and ‘2’ i.e. Give a reason for the same & name the compound CuCl & CuCl 2. Hence is cation Mg 2+ has valency 2 +.Įxplain the term ‘variable valency‘ Copper having electronic configuration 2, 8,18,1 exhibits variable valency. there are 2 valence electrons which Mg can lose and achieve stable configuration of nearest noble gas Neon. Valency of magnesium is 2 +, Mg Electronic configuration of Mg is 2, 8, 2 i.e. Valency of atom nitrogen is 3, as it combines with 3 atoms of hydrogen. Compound water H 2O, two atoms of hydrogen combine with one atom of oxygen to form water. Valency is the number of hydrogen atoms which combine with (or displace) one atom of the element forming a compound. With reference to water & ammonia as compounds respectively, state the valency of oxygen & nitrogen. Hence symbol of calcium is ‘Ca’ and symbol of copper or cuprum (Latin name of copper) is ‘Cu’.ĭefine the term ‘valency’. “Symbol of an element is the ‘first letter’ or the ‘first letter and another ‘letter’ of the English name or Latin name of the element”.Īs the name calcium and copper start with same letter of English alphabet ‘C’ so another letter from the name of the element is added to ‘C’. Symbol is a short form or abreviated name – of the element.

State a reason why – the symbol of calcium is ‘Ca’ & of copper is ‘Cu’ The adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight.Chemistry ICSE Class 8 Important Questions Chapter 5 Language of ChemistryĮxplain the term ‘symbol’. In humans, copper is found mainly in the liver, muscle, and bone. In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the iron-complexed hemoglobin in fish and other vertebrates. Copper compounds are used as bacteriostatic agents, fungicides, and wood preservatives.Ĭopper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the respiratory enzyme complex cytochrome c oxidase.

Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments.

Coper ( Old English) and copper were derived from this, the later spelling first used around 1530.Ĭommonly encountered compounds are copper(II) salts, which often impart blue or green colors to such minerals as azurite, malachite, and turquoise, and have been used widely and historically as pigments.Ĭopper used in buildings, usually for roofing, oxidizes to form a green verdigris (or patina).

In the Roman era, copper was mined principally on Cyprus, the origin of the name of the metal, from aes cyprium (metal of Cyprus), later corrupted to cuprum (Latin). 4000 BC and the first metal to be purposely alloyed with another metal, tin, to create bronze, c. Thousands of years later, it was the first metal to be smelted from sulfide ores, circa 5000 BC the first metal to be cast into a shape in a mold, c. This led to very early human use in several regions, from circa 8000 BC. Copper is one of the few metals that can occur in nature in a directly usable metallic form ( native metals).

Cuprum latin