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Chemical garden and The magic rocks Chemical garden and The magic rocks Chemical garden also known as 'silica garden' is grown by adding solid metal salts(usually transition metal salts) toan aqueous solution of sodium silicate (water glass).This results in growth of minute crystals (in few minutes to hours) that appear like creepers. The developed crystals are used in micro-fluid devices and in medicine. Different transition metal salts produce different colored crystals known as magic rocks.

Learning Objectives

After completing the topic, the student will be able to:

  • List group 14 or IVA elements and write their electronic configurations.
  • Discuss the extraction methods and uses of group 14 elements.
  • Describe the general trends in physical properties and examine the chemical properties of group 14 elements.
  • Compare the properties of carbon and silicon.
  • List the allotropes of carbon and their uses.
  • Give an account on versatility of carbon and its chemical behavior.
  • Discuss the chemical and physical properties of silicon.
  • List the types of silicates and give their structural features.
Group 14 elements

The carbon family is the periodic table group consisting of 6 elements: carbon(C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), and ununquadium (Uuq). Mnemonic: Chemistry Sir Generates Sandy Problems. In modern IUPAC notation, it is called Group 14 and as Group IVA in CAS systems. (In the field of semiconductor physics, it is still universally called Group IV. The Group was once also known as the tetraels (from Greek tetra, four), stemming from the Roman numeral IV in the Group names, or (not coincidentally) from the fact that these elements have four valence electrons).

Electronic configuration

Their configurations show that these elements have four electrons in their ultimate (valence) shell, two of which are in s–orbital while the remaining two are in p–orbital. Hence these elements possess s2p2 configuration in the valence shell. The penultimate shell of C contains s2 electrons, of Si contains s2p6 electrons and Ge contains s2p6d10 (unsaturated). This shows why carbon differs from Si and both from the other members of this sub–group. The electronic configuration of the carbon group elements are mentioned in the table.

Occurrence of the elements

The elements are all well known, apart from germanium. Carbon is the seventeenth, and silicon the second most abundant element by weight in the Earth's crust. Germanium minerals are very rare. Ge occurs as traces in the ores of other metals and in coal, but it is not well known. Both Si and Ge are important for making semiconductors and transistors. Though the abundances of tin and lead are comparatively low, they occur as concentrated ores which are easy to extract.Both these metals have been well known since before biblical times.

Carbon occurs in large quantities combined with other elements and compounds mainly as coal, crude oil, and carbonates in rocks such as Calcite (CaCO3), and Magnesite (MgCO3) and Dolomite (MgCO3. CaCO3).

Carbon is also found in the native form. Large amounts of graphite are mined and extremely small quantities (in tonnage terms) of diamonds are mined too. Both CO2 and CO are important industrially. CO2 occurs in small quantities in the atmosphere but has a vital role in the carbon cycle with photosynthesis and respiration. CO is an important fuel, and forms some interesting carbonyl complexes.

Silicon occurs very widely, as silica SiO2 (sand and quartz), and in a wide variety of silicate minerals and clays. Germanium is only found as traces in some silver and zinc ores, and in some types of coal. Tin is mined as cassiterite SnO2, and lead is found as the ore galena PbS.