In chapter 1 in the chapter summary on page 27, there are problems with the definitions of electron, proton, and neutron.
An atom is required to have electrons, but an electron is not required to always be part of an atom. It may be typical for an electron to be part of an atom, but this is not a requirement, not something that can be built into the definition.
To say the same thing another way: Words that might be more-or-less OK as a description of "atom" (on page 6) cannot be turned around and used as a definition of "electron".
Among other things, this violates the pedagogical principle that learning proceeds from the known to the unknown. You cannot define atom in terms of electrons, and then define electron in terms of atoms.
Similar words apply to protons and neutrons.
More generally: This can be considered an example of the idea that words acquire meaning from how they are used ... not from some pithy dictionary-style definition. Fundamental physics concepts cannot be defined in terms of anything more fundamental. See item #175.
Also: This illustrates what happens if the chapter summary tries to masquerade as a chapter «glossary» or vice versa. See item #171.
Suggestion:
The characteristic properties of an electron include its mass, charge, spin, and lepton number. It is not appropriate to explain all this in chapter 1, but it would be far better to leave the term undefined than to offer a bogus definition.
When I say "undefined" I mean explicitly undefined:
At this stage of the game, we are not going to define what we mean by electron, proton, or neutron. Instead we will build up an understanding, bit by bit, building it up over time. Atoms are made of electrons, protons, and neutrons ... but this tells you more about atoms than it does about the subatomic particles. The electrical interaction between electrons and protons is discussed starting in chapter 22. The behavior of electrons in wires is discussed in chapter 26 and especially chapter 31.
A more general discussion of definitions and "ideas before names" can be found in item #177.
In chapter 1 in the chapter summary on page 27, there are problems with the definitions of electron, proton, and neutron.
An atom is required to have electrons, but an electron is not required to always be part of an atom. It may be typical for an electron to be part of an atom, but this is not a requirement, not something that can be built into the definition.
To say the same thing another way: Words that might be more-or-less OK as a description of "atom" (on page 6) cannot be turned around and used as a definition of "electron".
Among other things, this violates the pedagogical principle that
learning proceeds from the known to the unknown. You cannot define atom in terms of electrons, and then define electron in terms of atoms.Similar words apply to protons and neutrons.
More generally: This can be considered an example of the idea that words acquire meaning from how they are used ... not from some pithy dictionary-style definition. Fundamental physics concepts cannot be defined in terms of anything more fundamental. See item #175.
Also: This illustrates what happens if the chapter summary tries to masquerade as a chapter «glossary» or vice versa. See item #171.
Suggestion:
The characteristic properties of an electron include its mass, charge, spin, and lepton number. It is not appropriate to explain all this in chapter 1, but it would be far better to leave the term undefined than to offer a bogus definition.
When I say "undefined" I mean explicitly undefined:
A more general discussion of definitions and "ideas before names" can be found in item #177.