Mono-Bond Typed Binary Compounds
Binary compounds – chemical substances made from just two chemical elements – are individually structurally simple, yet taken together the materials possess & exhibit a rich set of behaviours. The logical structure & reactivity arguments put forward in the Chemogenesis web book employ binary compounds as examples wherever possible.
Definition of Binary Compound
However, in this web book we use a slightly different, tighter and local – within Chemogenesis – definition:
- Binary compounds are materials/substances that exhibit only one type of strong chemical bond: metallic, ionic or covalent.
- We are interested in the sub-set of binary compounds that are: mono bond typed.
Many binary compounds fail our strict one-type-of-strong-chemical-bond requirement. For example, there are literally thousands of hydrocarbons (substances consisting of hydrogen and carbon only) including: methylene, CH2, methane, CH4, ethane, C2H6, ethene, C2H4, ethyne (acetylene), C2H2, benzene, C6H6, toluene, C7H8, polythene, [CH2]n, etc.
But ONLY methylene, CH2, and methane, CH4, possess only one type of strong chemical bond and are the only substances to be considered binary compoundshere.
The chemical elements as material substances are here – within the Chemogenesis web book – considered to be special case binaries where the two elements are identical: H2, O2, N2, etc. This definition also holds with bulk elemental materials: lithium, Li, carbon (diamond), C, carbon (graphite), C, silicon, Si, etc... that exist as extended lattice structures rather than forming discrete molecules.
Allotropes | Polymorphs | Particle Size
From the Wikipedia:
"Allotropy, or allotropism, is the property of some chemical elements to be able to take two or more different structural forms that exhibit quite different physical properties and chemical behaviours."
- Carbon can exist as: graphite, the thermodynamically stable form of carbon under standard conditions (25°C, 1.0 atm), diamond, fullerenes including: C60 buckyballs, SWCN (single walled carbon nanotubes), and many others.
- Oxygen can exist as dioxygen, O2, (a diradical which can exist in distinct singlet and triplet forms) and ozone, O3.
- Allotropes of: carbon, phosphorus, oxygen, nitrogen, sulfur, selenium, boron, silicon, arsenic, antimony, polonium, tin, iron, titanium, strontium, plutonium, ytterbium, terbium, promethium, curium, americium, berkelium and californium are discussed on the Wikipedia page.
From the Wikipedia:
"Polymorphism is the ability of a solid material to exist in more than one form or crystal structure. Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to elemental solids. Together with polymorphism the complete morphology of a material is described by other variables such as crystal habit, amorphous fraction or crystallographic defects.
- Silica, SiO2, has many polymorphs, including: α-quartz & β-quartz, tridymite, cristobalite, coesite, stishovite and silica gel.
- Walter McCrone stated that every compound has different polymorphic forms, and that, in general, the number of forms known for a given compound is proportional to the time and money spent in research on that compound.
The chemistry of a solid substance can be strongly influenced by the particle size.
- Magnesium oxide, MgO, is a refractory (heat resistant) material that is used to form the fire bricks that line furnaces and kilns. The chemistry of a sample of MgO consisting of a fine power will be rather different to the chemistry of a solid block of fire brick.
- Colloidal gold, wikipedia, or nanogold, is a suspension of sub-micrometre-sized particles of gold in a water. The liquid is usually either an intense red colour (for particles less than 100 nm), or a dirty yellowish colour (for larger particles).
|Periodicity||Binary Compound Synthlet|
© Mark R. Leach 1999 –
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