How does smell work on the atomic level?

In summary: Overall, the key takeaway is that density and smell are not directly related, but rather depend on various factors like vapor pressure and molecular shape.In summary, substances radiate particles through evaporation, with the rate varying based on density. However, the ability to detect specific molecules through smell is not directly related to density, but rather depends on factors like vapor pressure and molecular shape.
  • #1
Daveman20
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Do substances radiate particles? Is it the wind brushing up the surface particles of the substance? Do dense materials usually have less smell?
 
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  • #2
Daveman20 said:
Do substances radiate particles? Is it the wind brushing up the surface particles of the substance? Do dense materials usually have less smell?

All solids and liquids evaporate material constantly, yes, though the amount can vary by many orders of magnitude between a volatile liquid and a dense solid. And your intuition is correct, denser materials generally evaporate vapor at a smaller rate (ice cubes will disappear from your freezer in weeks, but a chunk of iron will stick around for a long, long, time). But the ability of the nose to detect specific molecules is another factor.
 
  • #3
Mapes said:
All solids and liquids evaporate material constantly, yes, though the amount can vary by many orders of magnitude between a volatile liquid and a dense solid. And your intuition is correct, denser materials generally evaporate vapor at a smaller rate (ice cubes will disappear from your freezer in weeks, but a chunk of iron will stick around for a long, long, time). But the ability of the nose to detect specific molecules is another factor.

great response, thanks mapes!
 
  • #4
The earlier post regarding density and vapor pressure is correct, however it is worth noting that the density of a material is completely unrelated to its "smell". Helium is less dense than air, but neither has any smell. On the other hand, pure acetone is several orders of magnitude more dense than any gas, yet it has a pungent smell.

On a molecular level, the biology of smell actually has to do with the shapes of molecules and how they "fit" (or fail to fit), in molecular receptors in your nose.
 

1. How do we perceive smell?

Our sense of smell is triggered by tiny odor molecules that float through the air and enter our noses. These molecules bind to receptors located in the olfactory epithelium, a small patch of tissue high in the nasal cavity.

2. What happens when we smell something?

When an odor molecule binds to a receptor, it triggers a series of chemical reactions that send an electrical signal to the olfactory bulb in the brain. From there, the signal is relayed to other areas of the brain involved in processing smell, such as the amygdala and the hippocampus.

3. How do different smells have different scents?

Each odor molecule has a unique shape and size, which allows it to bind to specific receptors in the nose. Different combinations of odor molecules binding to different receptors create a unique pattern of electrical signals that our brain interprets as a specific scent.

4. Can our sense of smell change over time?

Yes, our sense of smell can change over time. As we age, our olfactory receptors may become less sensitive, leading to a decreased sense of smell. Additionally, certain medications, illnesses, and environmental factors can also affect our sense of smell.

5. How do animals have a more acute sense of smell than humans?

Animals have a much larger olfactory epithelium and more olfactory receptors than humans, allowing them to detect a wider range of odor molecules. They also have a secondary olfactory system, called the vomeronasal organ, which is specifically designed to detect pheromones and other chemical signals.

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