# Question about the states of matter

• B
• Sundown444
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 materials.

#### 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?

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

ProfuselyQuarky said:
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.

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.

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ProfuselyQuarky said:
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.

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

ProfuselyQuarky said:
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.

Okay, then. Now you're sure :)

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.

jbriggs444 said:
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?

Sundown444 said:
You mean as in how tightly packed they are, right?
More like how inflexible the packing arrangement.

olgerm
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.

Khashishi said:
So, when you push your hand through, the molecules can bend shift around relatively freely.
In other words, the space between molecules can change.

ProfuselyQuarky said:
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.

jbriggs444 said:
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.

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.

Khashishi said:
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?

ProfuselyQuarky said:
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
jbriggs444 said:
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?

ProfuselyQuarky said:
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.