S-block metals

s-block metals as material filler

The lighter ones of the alkali- and alkaline earth metals (the non-noble metals in the left s-block of the periodic table) belong to the most abundant elements around. Thus its an iteresting question wheter those elements can be combined with other abundant ones to make structural building materials.

solubility issue

The s-block metals need to be combined with other elements not only because metals are not very suitable for mechanosynthesis but also because they are extremely reactive in pure form. A self passivation oxide layer film like the one that macroscopic blocks of magnesium have is obviously not possible on nano sized building blocks. In contact to air oxidation would go down right to the core of the building block and blow up the part twice in volume destroying it completely.

Since s-block metals are so electropositive they tend to toss away their shell electron or pair of shell electrons and thus tend to form ionic salts. Such a salt usually has the form:

• positively charged s-block-metal + negatively charged nonmetal-acid

Polar salts of this form are easily dissolved in water since water is a polar solvent. But good water solubility is not what one usually wants from a typical building material - especially not if the solvent is toxic like it is the case with many beryllium compounds. So the focus here will be on the few non or barely water soluble compounds.

barely soluble salts (*ates)

soft

When systematically building combinations of s-block metals and d-block nonmetal acids one can find some barely soluble compounds:

• calcium carbonate CaCO3 (limestone/chalk ... calcite/aragonite/vaterite)
• calcium phosphates (similar to hydroxyapatit bone tooth-enamel)
• calcium silicate CaSiO3 (dry wall plates ... wollastonite)
• magnesium silicate Mg2SiO4 (forsterite - no crystal water - pretty hard - neosilicate - earth mantle mineral)
• magnesium silicate Mg3Si4O10(OH)2 (talc - a hydroxide - way too soft for a building material)

Beryllium silicates:

• beryl Be3Al2(SiO3)6 (cyclosilicate) wikipedia
  varieties: emerald (green Cr), aquamarine (blue Fe), red beryl (red Mn), goshenite (colorless), heliodor (yellow Fe), and morganite (pink Mn)
• phenakite Be2SiO4 (neosilicate)
• bertrandite Be4Si2O7(OH)2 (hydorxide - pretty hard - sorosilicate)

hard (silicates only?)

Some harder silicate compounds containing aluminum too are:

• jadeite NaAl[Si2O6] (a chain/band silicate)
• pyrope Mg3Al2(SiO4)3 (a pyralspite garnet and neosilicate)
• grossularite Ca3Al2(SiO4)3 (an ugrandite garnet)

The hard ugrandite garnets are defined by their calcium content:

• grossularite Ca3Al2(SiO4)3
• andradite Ca3Fe2(SiO4)3
• uwarovite Ca3Cr2(SiO4)3 (contains rare chromium)

Other:

• amazonite K[AlSi₃O₈] Mohs 6-6.5

non salts but (*ides)

Probably the simplest barely soluble earth alkali compounds (that are not salts) are:

• calcium fluorite CaF2 (fluorite)
• magnesium oxide MgO (magnesia ... periclase)
• chrysoberyl BeAl2O4

[todo:]

• [find some insoluble alkali compounds Li Na K]
• [maybe find some compounds of the heavier and less abundant ones (Rb & Cs) (Sr & Ba)]
• [treat aluminum as special case]