• Skip to main content
  • Skip to secondary menu
  • Skip to primary sidebar

Class Notes

  • Home
  • Class 1-5
  • Class 6
  • Class 7
  • Class 8
  • Class 9
  • Class 10
  • Class 11
  • Class 12
  • NCERT Solutions
Home » Class 12 » Chemistry » General Principles and Processes of Isolation of Elements » Modes of Occurrence of Elements and Metals

Modes of Occurrence of Elements and Metals

Last Updated on February 16, 2023 By Mrs Shilpi Nagpal

Contents

  • 1 Modes of Occurrence of Elements
    • 1.1 1) Native State
    • 1.2 2) Combined State
  • 2 Abundance of Elements
  • 3 Mineral and Ores

Modes of Occurrence of Elements

The elements generally occur in the free state (called native state) or in the combined state. This is mainly because of different chemical reactivities of elements.

1) Native State

The elements which have very low reactivity and are not attacked by oxygen or air, moisture, carbon dioxide or other non-metals occur in the free state, called native state.

For example: carbon, sulphur, nitrogen, noble gases, metals like gold, silver, platinum, etc. occur in nature in the native state.

Therefore, these elements are also called native elements.

2) Combined State

The elements which are reactive and have a tendency to combine with oxygen or air, moisture, carbon dioxide and non-metals like carbon, nitrogen, sulphur, phosphorus, arsenic, halogen, etc. occur in the combined state.

These elements occur in the crust of the earth in the form of their compounds. In the combined state the non-metals are usually found in the reduced form and the metals in the oxidised form.

Among the metals, only a few metals, such as silver, gold, platinum, etc. occur in native state. Non-metals such as carbon and sulphur also occur in native state as well as in combined state.

Abundance of Elements

Distribution of Elements in Earth Crust

Most metals occur in the combined states. The most common forms of metals in the combined state are oxides, carbonates, sulphides, silicates, halides, sulphates, arsenides, phosphate, etc.

Among metals, aluminium is the most abundant. It is the third most abundant element in earth’s crust (8.31% by wt). It occurs widely as a constituent of rocks and soils. It is a major component of many igneous minerals including mica and clay.

Iron is the second most abundant metal in earth’s crust. It forms a variety of compounds which have various important uses. This makes iron a very important element. Iron is also one of the essential elements in biological systems.

Mineral and Ores

Most of the metals have a tendency to react with moisture, oxygen, sulphur, halogens, etc. and therefore, occur in the crust of the earth in the form of their compounds such as oxides, sulphides, halides, silicates, carbonates, nitrates, phosphates, etc.

The naturally occurring chemical substances in which metals occur in the earth’s crust are called minerals. The mineral, from which the metal can be economically and conveniently extracted, is called an ore.

The type of mineral from which the metal can be extracted is decided on the basis of
profitability.

For example: Metals are not generally extracted from silicate minerals because of the difficulties during extraction.

2) Aluminium occurs in the earth’s crust in the form of two minerals, bauxite (Al2O3.2H20)
and clay (Al2O3.2SiO2.2H20). Aluminium can be conveniently and economically extracted from bauxite, while it has not been possible to extract aluminium from clay by some easy and cheap method.

3) The main minerals of copper are copper glance (Cu2S), cuprite (Cu2O), copper pyrites (CuFeS2), malachite [CuCO3 Cu(OH)2], etc. but copper can be conveniently extracted from copper pyrites. Therefore, the ore of copper is copper pyrites. 

Metal Name Composition
Aluminium Bauxite AlOx(OH)3-2x
Feldspar KAlSiO8
Cryolite Na3AlF6
Kaolinite Al2(OH)4Si2O5
Iron Haematite Fe2O3
Magnetite Fe3O4
Siderite FeCO3
Iron Pyrites FeS2
Limonite Fe2O3.3H2O
Copper Copper glance Cu2S
Copper pyrite CuFeS2
Malachite CuCO3.Cu(OH)2
Cuprite Cu2O
Azurite 2 CuCO3. Cu(OH)2
Zinc Zinc blende ZnS
Calamine Zn2SiO4
Zincite ZnO.Fe2O3
Willemite ZnO.Fe2O3
Manganese Pyrolusite MnO2
Braunite Mn2O3
Calcium Limestone CaCO3
Gypsum CaSO4.2H2O
Magnesium Magnesite MgCO3
Dolomite CaCO3.MgCO3
Lead Galena PbS
Cerrusite PbCO3
Mercury Cinnabar HgS
Share with Friends

Filed Under: Chemistry, Class 12, General Principles and Processes of Isolation of Elements

Reader Interactions

Comments

  1. Ekramul says

    July 6, 2020 at 10:55 am

    Please upload the p block elements

Primary Sidebar

Recent Posts

  • Essay on Holi for Kids and Students
  • Jalebis – Class 8 English, Chapter 8 Notes
  • The Open Window – Class 8 English, Chapter 7 Notes
  • The Fight – Class 8 English, Chapter 6 Notes
  • Princess September – Class 8 English, Chapter 5 Notes
  • Facebook
  • Pinterest
  • Twitter
  • YouTube

© 2016 - 2023 · Disclaimer · Privacy Policy · About Us · Contact Us