Why are hydrogen atoms different from the atoms of all other elements ?

Because hydrogen only has one proton. Hydrogen can have any amount of nutrons and electrons in any combination but aslong as it has 1 proton it is hydrogen (a proton could be described as a hydrogen ion). In conclusion an element is deicided on by the atomic number (how many protons are in the atom). Btw the question asks what is the difference between a hydrogen atom and all other elements atoms. Ofc a hydrogen atom is made of 1 proton and 1 neutron but any other element can have 1 electron (ion) but no other element can have one proton in its nucleus.

Hydrogen contains one electron and one proton, so its shows similarities with the Alkali metals and Halogen family.

Its position is undefined in the long form of the periodic table.

It contains only one electron in its valence shell and the Lightest of all the periodic table elements.

So Hydrogen is different from the atoms of all other elements.

Actually hydrogen is really an element that is a lot like helium and chlorine at the same time. Although to answer your question Hydrogen is the only one electron in its first shell.

Because every atom is made up of different protons, neutrons, and electrons. The hydrogen atom is the simplest atom with only one proton and one electron.

Having but a single electron, Hydrogen disappears when it becomes a cation.

There are a lot of answers to that question. One can be that it's the simplest, one electron and one proton.

As it is the only one atom with H7 isotope