Atom models

Содержание и основные понятия

In the experience of Rutherford, the positive charge and almost all the mass of the atom are concentrated in a small core, and the electronic shell takes up the bulk.
GEF · Grade 9
PIF · Baseline
Interactive model
Atom
kernel
electron
Proton
neutron
isotop
01
The physical picture
What happens and what boundaries the model has.
Main message
In the experience of Rutherford, the positive charge and almost all the mass of the atom are concentrated in a small core, and the electronic shell takes up the bulk.
Most alpha particles pass through the foil almost without abnormality — the atom is mostly empty.
Rare strong variations point to a compact positive core.
A modern quantum model describes probability, not classical orbits of electrons.
How to reason
First, name the system and the interaction, then select the values, and only then write down the law. The formula works within the model's assumptions.
02
Laws and values
Symbols should be read as a relationship of values, not as a recipe for substitution.
Z
=
N
p
Z=N_p
Z
=
N
p
​
charge number
A
=
Z
+
N
A=Z+N
A
=
Z
+
N
mass number
Review of the situation
The isotopes of one element have the same number of protons, but different number of neutrons and therefore different mass numbers.
04
Links and application
In the real world
The isotopes of one element have the same number of protons, but different number of neutrons and therefore different mass numbers.
Model verification
Compare the prediction with observation, evaluate the units, the order of magnitude and the influence of the factors not taken into account. Disparity does not always mean an error of law: often idealization is no longer sufficient.
C
What needs to be understood
Outcome 1
Explain the physical meaning of the topic "Atom models" through the model, not just the formula.
Outcome 2
To distinguish and correctly use terms: atom, nucleus, electron.
Outcome 3
Indicate the conditions for the applicability of the law, verify units and limit cases.
T
Terms of the topic
The definition should indicate the physical meaning, not a substitute for a domestic synonym.
Atom
Electrically neutral system made of positive kernel and electronic envelope.
kernel
The central part of the atom is made up of protons and neutrons and contains almost all of its mass.
electron
Steady elemental particle with negative elementary electrical charge.
Proton
A positive charged nuclone with a module charge equals an electron charge.
neutron
An electrically neutral nuclone that enters with protons into the atomic nuclei.
isotop
A different element with the same number of protons, but a different number of neutrons.
F
Origin and conclusion of the formulas
The fundamental law cannot be "proven" by algebras: for each record, it is stated whether it is a definition, an experimental law, or a model effect.
Z
=
N
p
Z=N_p
Z
=
N
p
​
model effect
Charging number.
The following is an indication of the definition, experience or law from which this entry arises and where it is applicable.
q
ядра
=
N
p
e
q_{\text{ядра}}=N_p e
q
of kernels
​
=
N
p
​
e
Each proton carries a positive elementary charge e, so the core charge is determined by the number of protons.
q
ядра
=
Z
e
q_{\text{ядра}}=Ze
q
of kernels
​
=
Z
e
The charge number Z shall be inserted as the number of elementary positive charges of the kernel.
Z
e
=
N
p
e
⇒
Z
=
N
p
Ze=N_pe\Rightarrow Z=N_p
Z
e
=
N
p
​
e
⇒
Z
=
N
p
​
A comparison of the two records gives a definition of the equality between the charge number and the number of protons.
Conditions:
The atomic core; N_p is a whole number of protons, and Z is a chemical cell serial number.
Monitoring:
The dimensions of both parts shall coincide; the result shall be checked for sign, order and limit case.
A
=
Z
+
N
A=Z+N
A
=
Z
+
N
definition
Mass number.
The following is an indication of the definition, experience or law from which this entry arises and where it is applicable.
N
нуклонов
=
N
p
+
N
n
N_{\text{нуклонов}}=N_p+N_n
N
Noklons
​
=
N
p
​
+
N
n
​
The kernel consists of two types of nucleons: protons and neutrons.
A
≡
N
нуклонов
,
Z
=
N
p
,
N
=
N
n
A\equiv N_{\text{нуклонов}},\quad Z=N_p,\quad N=N_n
A
≡
N
Noklons
​
,
Z
=
N
p
​
,
N
=
N
n
​
The mass A shall be introduced as the total number of nucleons; Z and N shall indicate the numbers of protons and neutrons.
A
=
Z
+
N
A=Z+N
A
=
Z
+
N
The addition of symbols gives a definite connection that is not an approach to the mass of the kernel in kilograms.
Conditions:
The specific nuclide; A, Z and N are non-negative whole numbers, and A is not equal to the exact relative atomic mass.
Monitoring:
The dimensions of both parts shall coincide; the result shall be checked for sign, order and limit case.
!
Model boundaries and typical errors
Error: Forget model condition
The key condition of this topic is that most alpha particles pass through the foil almost without deviation, the atom is mostly empty.
How to Check the Mind
Rare strong variations indicate a compact positive core. Then check the units, vector direction, and result behaviour at zero or very large parameter.
Σ
Conclusion on the topic
Atom models
In the experience of Rutherford, the positive charge and almost all the mass of the atom are concentrated in a small core, and the electronic shell takes up the bulk.
Most alpha particles pass through the foil almost without abnormality — the atom is mostly empty.
Rare strong variations point to a compact positive core.
Any numerical result shall be accompanied by a unit, a sign and an explanation of its physical meaning.
The content is consistent with the FRP on Physics of the OS/OSS 2025 and the subject matter of the current lines of the PNP: I. M. Peryškin and co-authors (7–9), G. J. Mäkishev and coauthors (10–11), and with the lines "Engineers of the Future" and V. A. Kasyanov. The original texts are not reproduced, the text of the textbooks is not reproduced.