Physicians' High School Chemistry

It's not physical chemistry.
This draft will be longer than usual I did. Because I'm getting older. Because I didn't hear the viewpoints. Because I'm tired. Pardon me.

https://www.cnblogs.com/qianxinn/p/19125106

Introdution

First of all, I recommend

Physical Chemistry
by McQuarrie & Simon

but may not be the famous one(Atkins), because it uses physics in a strange way I maybe think.

My knowledge is limited about Chemistry also.

The Physical World of Chemists.

In chemistry， The reactions involve only the rearrangement of electrons.

The Periodic Table is the Physical World of Chemists.

Isotopes are atoms of the same element (same number of protons) that have different numbers of neutrons, and therefore, different masses.

And in high school, we used a simple The Periodic Table.

MW is Molecular Weight

\(u×N_A​ = Da×N_A​ = MW = \frac{g}{mol} = 0.001\frac{kg}{mol}\)

u, Da is Atomic Mass Unit, the mass of an atom.

1 u is exactly \(\frac{1}{12}\)​ of the mass of a single carbon-12 atom.

\(1 u = 1.66053906660×10^{−27} kg\)
\(N_A=6.02214076×10^{23} / mol\)
\(1 u N_A = 0.001 kg/mol = g/mol\)

\(H_{Mp} \approx 1.6726×10^{−27}kg\)

\(H_{Me} \approx 9.109×10^{−31}kg\)

\(H_{M} \approx 1.6735×10−27kg \approx 1.0078 u = 1.0078 Da\)

So H is 1MW, others are \(index * 2MW\). This is the The Periodic Table of high school. Sometimes, in some country, people will say 1 Da/u == 1 MW, but it's wrong.

So if you know a little Quantum Physics, you may think even the rearrangement of electrons also can change the atomic mass. Because atomic mass is not atomic Momentum,

Chemistry just approximates them. The Chemistry may depend on the context more than Physics.

Some Molar mass

3: Li 7MW
11: Na 23MW
13: Al 27MW
15: P 31MW
17: Cl 35.5MW
19: K 39MW
26: Fe 55.85MW

From Fe, it's hard to ignore the exact Molar mass so we just ignore them.

Molarity

\(M = \frac{mol}{L} = \frac{mol}{{dm}^3} = 0.001\frac{mol}{m^3}\)

why there's L? also we have \(ml = cm^3\)

The liter was originally defined in 1795 as the volume of 1 kilogram of water at its maximum density (4°C). the liter is classified as an "accepted" non-SI unit for use with SI, not a base unit. This distinction ensures consistency with the SI framework, where derived units like m³ are preferred for fundamental calculations.

Why use "Litre"?

Pure convenience and historical momentum. Saying "I need 50 millilitres (mL)" is far more intuitive and practical in a lab than saying "I need 50 cubic centimetres (cm³)" or "5 × 10⁻⁵ cubic metres." The concept of a "litre" is deeply embedded in every aspect of practical chemistry and commerce.

So we can remove litre and u/Da. But if we can not even remove litre, we just don't mention Da/u. Because Da can let a chemist think they know the principles of the world.