# What are the chemical similarities between gallium and barium?

I am analyzing nutrient concentrations in wood, and I have found that in all my samples the distribution of gallium and barium are closely related. As a related phenomenon, the presence of these elements also sometimes correlates to that of another pair of nutrients, calcium and strontium, but not always. For example, in samples from a humid site $\ce{Ba}$, $\ce{Ga}$, $\ce{Ca}$ and $\ce{Sr}$ are always closely related, but in samples from a dry site $\ce{Ba}$ and $\ce{Ga}$ remain correlated to each other, but are generally not strongly correlated with $\ce{Ca}$ and $\ce{Sr}$.

I would like to know what aspects of their respective chemistries might cause $\ce{Ga}$ and $\ce{Ba}$ to have this strongly correlated relationship in wood samples. For example, is there some sort of similarity in how their valence electrons participate in bonding?

• I would think we should explain why its probably not chemistry related: Metals are mainly biologically active as ions. Barium makes a large +2 ion while strontium makes a small +3 ion. This difference makes it unlikely that they would substitute for one another. In contrast, lithium treats bipolar disorder by interfering with the sodium systems in the brain; this works because they're both small +1 ions. This points to the idea that they do not serve similar roles. In addition to a biological system using both of them in separate roles, it may also be geologically caused. – ericksonla Jan 14 '16 at 17:25
• See "Trace metals in soils, plants, and animals", ADVANCES IN AGRONOMY, Volume 24, especially at page 295, which suggests that solubility of barium and gallium are promoted by poor drainage conditions. books.google.com/… – DavePhD Jan 14 '16 at 18:26
• @ericksonla I agree, this aspect of the differences between the ions would be on-topic to Chem.SE. However, I think the question as-written is too broad. Darwin, if you're interested in the ion size aspects raised by ericksonla, by all means put together another question focused thereon and post it on Chem.SE. – hBy2Py Jan 14 '16 at 18:43
• @Brian since Ga, Ba, Ca and Sr are chemical elements (or nutrients) I posted my question here. I think my question is clear and it is related to observed chemical phenomenal in my measurements. Just I want to know some common characteristics between these elements. E.g. they use only the outermost shell orbitals in bonding or something like that. DavePhD gave a very good contribution, but you just want to put as off-topic my question with any contribution. Then, tell me how I can write to sound like a chemistry question? – Darwin PC Jan 14 '16 at 20:40
• @ericksonla - as a group II metal, strontium does not make a +3 ion – Ben Norris Jan 15 '16 at 23:10