Physical change chemical change?

Click For Summary

Discussion Overview

The discussion revolves around the definitions and distinctions between physical changes and chemical changes in chemistry, with a particular focus on the implications of nuclear changes such as radioactive decay. Participants explore the nuances of these categories and question the adequacy of traditional definitions.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that traditional definitions of physical and chemical changes are vague and arbitrary, particularly in distinguishing between changes that are visible and those that are fundamental.
  • One participant proposes that nuclear reactions, which involve changes in the nucleus of an atom, should be classified separately from chemical reactions, which only involve changes in electron arrangements.
  • Another viewpoint argues that nuclear changes are fundamentally physical changes, as they alter the properties of the atom and its potential chemical interactions.
  • Some participants express the idea that the terminology used in chemistry may be misleading, with "physical" changes being applied to more superficial alterations, while fundamental changes are associated with physics.
  • A participant highlights that the classic distinction in high school chemistry often centers on whether a new compound is formed, rather than the nature of the change itself.
  • Another perspective suggests that reversibility can be a criterion for distinguishing between physical and chemical changes, using melting ice and burning a match as examples.

Areas of Agreement / Disagreement

Participants generally agree that the definitions of physical and chemical changes are not entirely satisfactory, but there is no consensus on how to categorize nuclear changes or the implications of these definitions.

Contextual Notes

Participants express uncertainty regarding the definitions and classifications of changes in matter, particularly in relation to nuclear processes and the implications for chemistry and physics. The discussion reflects a range of interpretations and assumptions about the nature of these changes.

pivoxa15
Messages
2,250
Reaction score
1
In chemistry class they talk about physical change as something changing that is easily seen by the naked eye and chemical change as something more fundalmental that is something changing such as Na and Cl combining to form salt which is way different to Na or Cl.

But what happens if you change the number of protons in an atom like a radioactive decay. It is not chemical and obviously not physical so what change is it?
 
Physics news on Phys.org
Those definitions for physical and chemical changes are kind of vague and arbitrary, don't you think?

I would call a reaction involving a change in the particles of a nucleus a nuclear reaction, which actually changes the *type* of the atoms involved, as opposed to a chemical reaction, in which the type of the atoms involved does not change, only their arrangement; they are recombined to form different substances or compounds. Particles in the atomic nuclei aren't affected. Chemical reactions only involve changes to the the electronic structure (meaning the structure of electrons) in the valence shells of the atoms involved...bonds are formed or broken, etc. etc. I'm being pretty general too.
 
I think they are pretty vague also. I was thinking that we normally associate fundalmental changes as physics and chemistry as a subfield of phyics. But chemists try to look as though they are the important ones using the word physical for even smaller changes than chemical change. Nuclear change seems appropriate for a change in the structure of the nucleus but that is physics but they have already used up the word physical.
 
pivoxa15 said:
But what happens if you change the number of protons in an atom like a radioactive decay. It is not chemical and obviously not physical so what change is it?

That is most certainly a "physical" change. In addition, a change of atomic protons will change the properties of the atom itself, including it's potential "chemical" interaction, as the potential electron shell structure is likewise altered.
 
pallidin said:
That is most certainly a "physical" change. In addition, a change of atomic protons will change the properties of the atom itself, including it's potential "chemical" interaction, as the potential electron shell structure is likewise altered.

The chemist has already used the word physicsal for changes that are apparent to the naked eye like a broken stick has physically changed compared to the original non broken stick
 
The classic physical vs. chemical change lecture from HS Chem is not really a question of what is a physical change. Technically, things are being physically changed, moved around, etc on some level.

Really what the teacher is asking is "does this form a new compound or not".
 
Also, another good way to think is, after the change can you put it back?

If ice melts can you make it from water to ice again? Yeah, you freeze it.

If you burn a match can you turn it into an unburned match again? No, you can't put all the smoke and heat back in.
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
8K
  • · Replies 16 ·
Replies
16
Views
6K
  • · Replies 3 ·
Replies
3
Views
6K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 24 ·
Replies
24
Views
4K
  • · Replies 0 ·
Replies
0
Views
979
  • · Replies 5 ·
Replies
5
Views
7K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
2
Views
1K
  • · Replies 9 ·
Replies
9
Views
5K