Question about the states of matter

[Sundown444]

I have a question, and it is this: why is it that your hand can go through a gas or liquid while the same can't be done with solids? Is it because of density?

 

[ProfuselyQuarky]

Indeed, it has to do with density. Do you know the difference between how atoms are arranged in the different states of matter?

 

[Sundown444]

Indeed, it has to do with density. Do you know the difference between how atoms are arranged in the different states of matter?

Kind of. I believe I do in a way.

 

[ProfuselyQuarky]

See the image http://www.msm.cam.ac.uk/SeeK/slg.html [Broken]?

The atoms are closely packed together in the solid, but they become increasingly spread apart for the liquid and gas. There is more space between the atoms in the two latter states.

 

[Sundown444]

See the image http://www.msm.cam.ac.uk/SeeK/slg.html [Broken]?

The atoms are closely packed together in the solid, but they become increasingly spread apart for the liquid and gas. There is more space between the atoms in the two latter states.

Yeah, I actually did know that, but thanks, anyway.

 

[ProfuselyQuarky]

So if you knew that, what exactly were you asking? You could clarify and then I could help you better

 

[Sundown444]

So if you knew that, what exactly were you asking? You could clarify and then I could help you better

I just wasn't completely sure about it.

 

[ProfuselyQuarky]

Okay, then. Now you're sure :)

 

[jbriggs444]

The density of a substance has quite little to do with whether you can move your hand through it.

You can push your hand through liquid water more easily than you can push your hand through a cube of expanded polystyrene (styrofoam). What matters is not so much how dense the material is, but how firmly the component molecules are bound into a matrix.

 

[Sundown444]

The density of a substance has quite little to do with whether you can move your hand through it.

You can push your hand through liquid water more easily than you can push your hand through a cube of expanded polystyrene (styrofoam). What matters is not so much how dense the material is, but how firmly the component molecules are bound into a matrix.

You mean as in how tightly packed they are, right?

 

[jbriggs444]

You mean as in how tightly packed they are, right?

More like how inflexible the packing arrangement.

 

[Khashishi]

It's not just density. Water is denser than ice, you know. In a solid, all the molecules are bound together in an orderly formation, so you have to break many bonds to move your hand through. In a liquid, the molecules stick together but aren't in a tight formation. The molecules are all disorganized. So, when you push your hand through, the molecules can bend shift around relatively freely.

 

[ProfuselyQuarky]

So, when you push your hand through, the molecules can bend shift around relatively freely.

In other words, the space between molecules can change.

 

[jbriggs444]

In other words, the space between molecules can change.

No. The arrangement of the molecules can change. The [average] space between them need not change.

 

[ProfuselyQuarky]

No. The arrangement of the molecules can change. The [average] space between them need not change.

But it can. That's all I was saying.

 

[Khashishi]

I don't know if the difference between a liquid and solid is totally cut and dry. There's not a whole lot of difference between a very high viscosity liquid and and amorphous solid. Practically speaking, solids won't flow, but ductile metals can be pressed into shape with enough force.

 

[ProfuselyQuarky]

I don't know if the difference between a liquid and solid is totally cut and dry. There's not a whole lot of difference between a very high viscosity liquid and and amorphous solid. Practically speaking, solids won't flow, but ductile metals can be pressed into shape with enough force.

That is something I often wonder. Like, is lotion a solid or liquid? A semi-liquid? A semi-solid?

 

[jbriggs444]

But it can. That's all I was saying.

In a liquid, the average space between molecules does not change. And yet liquids flow. In a solid, the average space between molecules does not change. But solids do not flow [much]. The average spacing between molecules can not be the determining feature. That is what I am trying to point out.

 

[ProfuselyQuarky]

In a liquid, the average space between molecules does not change. And yet liquids flow. In a solid, the average space between molecules does not change. But solids does not flow [much]. The average spacing between molecules can not be the determining feature. That is what I am trying to point out.

Fair enough.

Now what about this: is lotion a solid or liquid? A semi-liquid? A semi-solid?

 

[jbriggs444]

Now what about this: is lotion a solid or liquid? A semi-liquid? A semi-solid?

A suspension of oil droplets in water. Or of water droplets in oil. Kashishi's point seems good. The distinction between a solid and a liquid is not always sharp, especially in composite substances.