Let's create an alien biosphere!

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Why would elemental chlorine form anyway? The only explanation I can think of is biological. Can you think of any other source?

No, but chlorine is probably gong to incorporate itself into other compounds, so organisms will need some way of removing it.

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No, but chlorine is probably gong to incorporate itself into other compounds, so organisms will need some way of removing it.

Sorry, I'm having trouble understanding your point. Do you want chlorine or not?

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Sorry, I'm having trouble understanding your point. Do you want chlorine or not?

I'd prefer to not have it, but I'm worried that getting rid of it would be unrealistic.

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I'd prefer to not have it, but I'm worried that getting rid of it would be unrealistic.

Why would it be there in the first place?

No, but chlorine is probably gong to incorporate itself into other compounds, so organisms will need some way of removing it.

You said this, but I don't understand why organisms would need to remove it.

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Why would it be there in the first place?

volcanoes

You said this, but I don't understand why organisms would need to remove it.

because it's probably going to react with other compounds

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volcanoes

I thought you'd said that they make compounds with chlorine. I was talking about chlorine gas (Cl2).

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I thought you'd said that they make compounds with chlorine. I was talking about chlorine gas (Cl2).

Actually, come to think of it, the amount of chlorine is probably negligible.

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Actually, come to think of it, the amount of chlorine is probably negligible.

So I think you got what you want. Though I would still like to have a much more abundant amount of something. Is copper or iron okay? You had said we could have altogether more transition metals, which I agree with, but I think we should choose one material to have a lot of. Also, from now on, chlorine = Cl2 unless otherwise specified.

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So I think you got what you want. Though I would still like to have a much more abundant amount of something. Is copper or iron okay? You had said we could have altogether more transition metals, which I agree with, but I think we should choose one material to have a lot of. Also, from now on, chlorine = Cl2 unless otherwise specified.

I think that the transition metals will be biologically useful in general except for the particularly unreactive ones (and even that's more of a guideline than a rule).

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I think that the transition metals will be biologically useful in general except for the particularly unreactive ones (and even that's more of a guideline than a rule).

Well yeah I know that but I'd still like to choose one element that is much more abundant than normal. As you said, metals might be too heavy to be used structurally but might they have other uses in higher quantities? And we're not restricted to metals either. We could maybe do something like a metalloid.

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Well yeah I know that but I'd still like to choose one element that is much more abundant than normal. As you said, metals might be too heavy to be used structurally but might they have other uses in higher quantities? And we're not restricted to metals either. We could maybe do something like a metalloid.

Nuclear physics tends to favor elements with even atomic numbers. Silicon, iron, nickel, tin, lead, and certain other elements with even atomic numbers are especially favored.

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Nuclear physics tends to favor elements with even atomic numbers. Silicon, iron, nickel, tin, lead, and certain other elements with even atomic numbers are especially favored.

I was thinking of silicon (28% of Earth's crust), but it is mostly in the form of silicate. Can you think of any ways around this or any other element(s)?
Also, why is it that even-atomic numbered elements are more common? I've never heard of that before.

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I was thinking of silicon (28% of Earth's crust), but it is mostly in the form of silicate. Can you think of any ways around this or any other element(s)?
Also, why is it that even-atomic numbered elements are more common? I've never heard of that before.

It's related to the nuclear shell model. The trend is illustrated in https://upload.wikimedia.org/wikipedia/ ... e-bars.svg.

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It's related to the nuclear shell model. The trend is illustrated in https://upload.wikimedia.org/wikipedia/ ... e-bars.svg.

It seems like the even ones are higher, but not by too much, so we shouldn't rule them out. What do you think of silicon?

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It seems like the even ones are higher, but not by too much, so we shouldn't rule them out. What do you think of silicon?

I think that it could be useful. It's already the second-most abundant element in Earth's crust.

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I think that it could be useful. It's already the second-most abundant element in Earth's crust.

Then I'd like one of two things, naturally occurring pure silicon or life evolving a way to use it (pure or impure).

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Then I'd like one of two things, naturally occurring pure silicon or life evolving a way to use it (pure or impure).

It could theoretically be used in biological molecules. Also, diatoms use cell walls made of silicon dioxide.

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It could theoretically be used in biological molecules. Also, diatoms use cell walls made of silicon dioxide.

That's interesting! I did not know that. Perhaps life could evolve something like this very early on and it would be in all life.

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That's interesting! I did not know that. Perhaps life could evolve something like this very early on and it would be in all life.

It's probably not going to be universal because it would be fairly heavy, but life could find other uses for silicon. For example, silicates could probably fulfill many of the roles that phosphate fills in life on Earth.

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It's probably not going to be universal because it would be fairly heavy, but life could find other uses for silicon. For example, silicates could probably fulfill many of the roles that phosphate fills in life on Earth.

Life can probably de-evolve it or find alternatives if it gets too heavy. Could it perhaps be used as armor? As for phosphates, I don't know much about their role in life. Can you give me an example of how silicon could replace it?

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Life can probably de-evolve it or find alternatives if it gets too heavy. Could it perhaps be used as armor? As for phosphates, I don't know much about their role in life. Can you give me an example of how silicon could replace it?

The body uses phosphates in ATP. Phosphate groups are negatively charged and therefore repel each other, so compounds that store them close together store electrical potential energy. ATP has three phosphate groups in a row, and detaching the one at the end releases energy that can be used to power other reactions. My idea was that because silicic acid has more OH groups than phosphoric acid, it make deprotonate into anions that are more negative on average and thereby enable the equivalent of ATP to store more energy per molecule; however, I later realized that the decreased electronegativity of silicon relative to phosphorus would more than cancel that out, so that wouldn't work. However, silicon could be useful in other roles due to its differing chemical properties, such as the fact that it is more electropositive and forms more stable single bonds to oxygen compared to other elements that could be used instead.
Also, I just remembered that aluminum oxide is less dense than aluminum, which is already less dense than most metals (which is one of the reasons why it's used in airplanes) and very strong (Its mineral form is corundum.), so perhaps some creatures could use that. (Aluminum is the third-most abundant element in Earth's crust, so creatures on our alien planet that use it will likely be able to get enough of it.)

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Life can probably de-evolve it or find alternatives if it gets too heavy. Could it perhaps be used as armor? As for phosphates, I don't know much about their role in life. Can you give me an example of how silicon could replace it?

The body uses phosphates in ATP. Phosphate groups are negatively charged and therefore repel each other, so compounds that store them close together store electrical potential energy. ATP has three phosphate groups in a row, and detaching the one at the end releases energy that can be used to power other reactions. My idea was that because silicic acid has more OH groups than phosphoric acid, it make deprotonate into anions that are more negative on average and thereby enable the equivalent of ATP to store more energy per molecule; however, I later realized that the decreased electronegativity of silicon relative to phosphorus would more than cancel that out, so that wouldn't work. However, silicon could be useful in other roles due to its differing chemical properties, such as the fact that it is more electropositive and forms more stable single bonds to oxygen compared to other elements that could be used instead.

What are the implications of more stable single bonds? Perhaps the ability to store certain molecules at higher temperatures because they wouldn't break apart as easily?

Also, I just remembered that aluminum oxide is less dense than aluminum, which is already less dense than most metals (which is one of the reasons why it's used in airplanes) and very strong (Its mineral form is corundum.), so perhaps some creatures could use that. (Aluminum is the third-most abundant element in Earth's crust, so creatures on our alien planet that use it will likely be able to get enough of it.)

That sounds interesting. What are the chemical processes needed to get its oxide or pure form? I just want to make sure something like this is plausible.

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What are the implications of more stable single bonds? Perhaps the ability to store certain molecules at higher temperatures because they wouldn't break apart as easily?

One possibility is replacing the phosphate in DNA's backbone with silicate in order to make DNA more stable. However, because ATP was originally created (along with GTP (which also is used by some enzymes), CTP, and TTP) in order to provide DNA polymerase with nucleotides to put together and a source of energy to drive the reaction, and other enzymes use it because it's more convenient than creating another energy-storing molecule, this could reduce the amount of energy stored for the reasons mentioned earlier. Also, because silicate doesn't tend to dissociate as much, DNA wouldn't have as much of a negative charge, so coiling it would likely be easier.

That sounds interesting. What are the chemical processes needed to get its oxide or pure form? I just want to make sure something like this is plausible.

I wouldn't worry about it because organisms on Earth seem perfectly capable of making shells made of other minerals.

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One possibility is replacing the phosphate in DNA's backbone with silicate in order to make DNA more stable. However, because ATP was originally created (along with GTP (which also is used by some enzymes), CTP, and TTP) in order to provide DNA polymerase with nucleotides to put together and a source of energy to drive the reaction, and other enzymes use it because it's more convenient than creating another energy-storing molecule, this could reduce the amount of energy stored for the reasons mentioned earlier. Also, because silicate doesn't tend to dissociate as much, DNA wouldn't have as much of a negative charge, so coiling it would likely be easier.

So what do you think is likely to happen in this case?

I wouldn't worry about it because organisms on Earth seem perfectly capable of making shells made of other minerals.

Animals on Earth using other minerals doesn't necessarily mean this is impossible. It could be that they just never evolved it. If you think the evolutionary pathway is too elaborate though, we can scrap the idea.

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So what do you think is likely to happen in this case?

Nucleic acids would probably start with silicate.

Animals on Earth using other minerals doesn't necessarily mean this is impossible. It could be that they just never evolved it. If you think the evolutionary pathway is too elaborate though, we can scrap the idea.

I meant that I wouldn't worry about it potentially being impossible.