# Tag Info

19

Okay, for this scenario, the two concepts that play a key role are the lattice enthalpy and the hydration enthalpy. Lattice enthalpy is the energy released when one mole of a compound is formed from its constituent gaseous ions under standard conditions. Lattice enthalpy is dependent on the length of the ionic bond between the cation and the anion in the ...

16

There is some disagreement in usage among authors, but IUPAC standard nomenclature approves calling beryllium an alkaline earth metal, as explained on page 51 of IUPAC's last Red Book. In fact, all the elements belonging to group 2, $\ce{Be,Mg,Ca,Sr,Ba,Ra}$, are called alkaline earth metals with IUPAC's approval. Other common traditional names approved by ...

7

According to this Wikipedia solubility table, lithium bicarbonate is soluble in water to $\pu{5.7 g/100mL}$ at $\pu{20^oC}$, while this Wikipedia page gives the solubility of magnesium bicarbonate as $\pu{0.077 g/100mL}$. However, another source (found by Oscar Lanzi in his good answer), "The Solubility of Magnesium Carbonate in Aqueous Solutions of ...

6

I beg to differ on magnesium bicarbonate. In https://books.google.com/books?id=bCfzAAAAMAAJ&pg=PA583&lpg=PA583&dq=magnesium+bicarbonate+solubility&source=bl&ots=3c8f8q4ocI&sig=XAY4Z50JRHq3FBRe8VPZjDf10sA&hl=en&sa=X&ved=0ahUKEwj91byQ3qPTAhVCOSYKHdNuDAw4ChDoAQgcMAE#v=onepage&q=magnesium%20bicarbonate%20solubility&f=...

5

This answer is an extension to @Ian Bush answer. Not only magnesium, but every group 2 element has a lower oxidation state of +0(beryllium) and +1(for other metals). Be(0) A 2016 paper gives an insight to the existence of a zero valent beryllium complex compound i.e it has been verified through computational method but it is yet to be synthesized. [......

5

Like a lot of things in chemistry, "it depends". Magnesium oxide is commonly produced by calcination of magnesium hydroxide or carbonate. The magnesium hydroxide or carbonate decomposes at a fairly low temperature whereas magnesium oxide is itself stable to both decomposition and melting beyond 2000°C. So, we can choose from a wide range of calcining ...

4

A few weeks ago I would have given the hard soft acid base theory (HSAB) explanation. I have heard this "trend" explained in this way: Hydroxide is hard and sulfate is soft. So, the harder ions are, the more soluble with sulfate and less with hydroxide. About a week ago I was playing around with some DH, lattice energy, and Ksp data and I found that ...

4

Magnesium(I) compounds are known, but they are of the form $\ce{[Mg-Mg]^{2+}}$ rather than a bare $\ce{Mg+}$ - so more like Mercury than Sodium. See https://pubs.rsc.org/en/content/articlelanding/2011/dt/c0dt01831g#!divAbstract, and in a way this furthers the similarity between Mg and Zn. Similar compounds are also possible for the heavier metals.

3

"Insoluble (in water)" is a relative term, especially for ionic compounds, and so is "alkaline". That relativeness gives us enough wiggle room for two of our most common bases to slip through. Roughly speaking, it takes a thousand volumes of water to react with and then dissolve one volume of calcium oxide, so the solubility of lime in water would not be ...

2

First off, to not overlook the obvious, both reactions ares thermodynamically favored. $$\ce{MgO (s) + H2O (l) -> Mg(OH)2 (aq)} \\ \Delta G_\pu{298K}^\circ = \pu{-833.7 kJ mol-1 -( -569.3 kJ mol-1 + -306.7 kJ mol-1) = - 42.3 kJ mol-1}$$ \ce{CaO (s) + H2O (l) -> Ca(OH)2 (aq)} \\ \Delta G_\pu{298K}^\circ = \pu{-(-754.2 kJ mol-1 + -306.7 kJ mol-1) +...

1

From NCERT (India) 11 page 296 under "The s-block elements": The carbonates of lithium and magnesium decompose easily on heating to form the oxides and $\ce{CO2}$. Solid hydrogen carbonates are not formed by lithium and magnesium.

1

If we're going to be fussy about alkaline earth metals being "alkaline earth" in the proper sense, then there are only two of them: calcium and magnesium. Beryllium oxide fails to be alkaline and the heavier Group 2 oxides (or, the hydroxides formed upon reaction with water) are too readily soluble to really be "earth-s" (hyphen included because my device ...

1

Alkaline metals are called so because of two reasons: They are obtained from the earth in the form of ores Their oxides and hydroxides show basic (alkaline) natures. Beryllium fulfills the first criterion but not the second one, since its oxides and hydroxides show amphoteric behavior, rather than alkaline. So, it is not considered an alkaline earth metal ...

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