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The number of elements has been changed from 92 to 94, can someone explain? I thought Uranium (92) was the last naturally occuring element. Where did the other 2 come from? -- Tango 16:54, 24 Apr 2004 (UTC)

Neptunium and Plutonium were found to occur in trace amounts due to Uranium decomposition.
Darrien 05:51, 25 Apr 2004 (UTC)

Fair enough. That should probably be mentioned in the article, as 92 is more commonly known, AFAIK. -- Tango 11:48, 25 Apr 2004 (UTC)

The atom is not the simplest particle that makes up matter. Atoms are the result of an accumulation process that accumulates mass particles plus electrostatically charged particles.

"It is the most simple type of particle that makes up matter."[change source]

An atom is not the most simple type of matter, but I can't come up with a better way to phrase that part of the article. Any help?

Well, the definition of an atom includes several concepts. I figure that here in Simple we shouldn't have to squeeze them into the one sentence. Here is the definition part of the article as it was at 12:12, 20 November 2009 (UTC):
An atom is the most simple type of particle that makes up matter. Matter is anything that has mass and takes up space. It is the smallest part of an element that still has the properties of that specific element. ...
The first AND third sentences make up the definition, right? The second I think is just getting in the way. Here is my rearrangement, spread over 2 sentences, with 2 more for extra information:
An atom is a particle that makes up matter. It is the largest part of an element that still has the chemical properties of that specific element. The atom cannot be broken down using physical means or chemical reactions, so it was once thought to be the smallest and simplest particle of matter. Each type of atom has its own name, mass and size. ...
Willing to make it clearer/more exact if necessary. The angel jean (talk) 12:49, 20 November 2009 (UTC)
An atom is defined as the smallest particle of any element that has all the characteristics (chemical and physical properties) of that element.

Hello fellow editors from times long gone, for the first sentence I went with "Atoms are very small pieces of matter." I agree with the sentiment that "we shouldn't have to squeeze the definition into one sentence". Furthermore the sentence "It is the largest part of an element that still has the chemical properties of that specific element." or any variation that uses chemical element to define atoms I find a bit confused, since the concepts are so close to each other, it leads to a circular definition. The source of the circular definition is probably the same as the one in English Wikipedia: "Smallest particle still characterizing a chemical element" from We see the circularity when the same source defines chemical element as: "a species of atoms; all atoms with the same number of protons in the atomic nucleus.", a second entry in chemical element reads "A pure chemical substance composed of atoms with the same number of protons in the atomic nucleus ." which explains the confusion in the previous definition, we are now using chemical element to refer to a species of atoms, not a substance composed entirely of atoms. I find the current form "There are many different types of atoms, each with its own name, mass and size. These different types of atoms are called chemical elements" much more enlightening and still consistent with the IUPAC definitions while opting for clarity instead of exactitude.

Thank you. Tomás Zubiri, Buenos Aires, Argentina - July 2020

Clarification[change source]

"Atoms ... have diameters of about 10-8."

10-8 (the "-8" is an exponent, of course) what? Centimeters? you say that but how do you know that? Where did you learn this?

= 10-8 means 10E-8 centimeters (cm) from the cgs system of science notation.WFPMWFPM (talk) 21:56, 20 October 2008 (UTC)
== Atoms =are accumulations of individual particles called "nucleons" into a "nucleus", which contains the nucleons, which is then contained within a large surrounding volume of space. Nuclear physics is about activity related to the nucleus. Chemical activity is about activity between atoms.WFPMWFPM (talk) 21:56, 20 October 2008 (UTC)
= The Atom is a The result of an accumulation process of the "proton" and "neutron" particles of matter the are found to exist in space and in the stars. This process results in the emission of "light energy" and other rediation which are observed and studied by "astronomers". Most Atoms are small and have atomic mass values from a minimum of 1 to around 16, but large atoms up to mass values of up to 238 have been discovered on earth. WFPMWFPM (talk) 00:30, 21 October 2008 (UTC)
== In addition to matter, the atom is known to have "electrostatic" and electromagnetic" properties that cause it to create and interact with forces of attraction and repulsion that far exceed the force of "gravitational attraction" that caused them to congregate in the first place. These forces are theorized to occur due to the existence of a third particle of the atom, named "the electron" which has a "negative" charge, and which is balanced in each individual "neutral" atom by an equal "positive" charge occurring in each of the "protons contained within the "nucleus" of the atom. These "electrons" are not tightly bound to the nucleus of the atom and can be separated: in which the atom retains a "positive" charge as a separate particle or becomes an "atomic ion" in a liquid solution. WFPMWFPM (talk) 00:56, 21 October 2008 (UTC)
== In a further attempt to organize information about atoms, their "chemical properties have been investigated and organized into different categories of "elements", with each element being atoms that have the same number of positive protons and negative electron and therefor similar chemical properties. Further study of these chemical properties led to the discovery of the "periodic" occurrence of similarities of certain chemical (and physical) properties and lead to the creation of tables of the elements related to these properties, and rather disregarding the fact that they didn't have anything to do with the nucleic accumulation atom creation process in the first place. Thus the "periodic table" was created as a way to organize chemical information "By Mendelev and others" and then "elaborated" to include elemental chemical and physical properties, and neglecting the details of the atom creation process, which is an important subject matter of "Nuclear Physics".WFPMWFPM (talk) 01:24, 21 October 2008 (UTC)

We need to explain more in this or at least

Some PGA comments[change source]

  • Hydrogen, for example, has one proton, no neutrons and no electrons - Wrong. It has one electron and is then called Protium (at least in Germany, dunno of there is an other English name.
Thats just a mistake, I did know that :) Its supposed to say one electron. FSM Noodly?
  • the element Sulfur has 16 protons, 16 neutrons and 16 electrons. - If you chose this example, you should say that number of neutrons can change (here between 14 and 24)
For it to be Sulfur it has to have 16 neutrons, otherwise its an isotope of Sulfur. The plain element defined as Sulfur has 16 neutrons. Or at least thats what I thought, maybe I'm wrong... FSM Noodly? 20:31, 2 January 2010 (UTC)

In the "Structure and Parts" section": The Nuclear shell model is missing. It belongs to the atom.

This is just after an overview. I'll have a deeper look in it tomorrow. --Barras talk 22:12, 18 December 2009 (UTC)

  • A periodic table would be fine in the article.
  • Bohr model should be explained (nuclear shell model).
  • high energy physics - atomic bomb, atomic power
  • the different enegergy levels of atoms

This is what is missing here atm (or not enough explained). I didn't read it now to say that the rest is ok. Just after an overview. Please fix first those issues. After this I'll read it completely. Regards --Barras talk 17:01, 19 December 2009 (UTC)

These definitions exclude isotopes[change source]

Saying "Hydrogen, for example, has one proton, no neutrons and one electron" is misleading as it excludes from the beginning the existence of isotopes. I would say "Hydrogen, for example, has one proton, one electron, and between 0 and 2 neutrons, depending on the isotope"... There are other instances of this article where this is not clear and misleading Thank you. Stefano Gatto, Geneva, Switzerland

Thanks for the critique, I changed that paragraph to focus on protons, since the identity of an element depends on their chemical properties, and these do not change a lot if the amount of electrons changes, but they do if the amount of protons changes. I also improved wording to hopefully clarify the differences between the three subatomic particles.

Finally, I further refined the initial definition continuing the work of Jim.henderson, I went for piece instead of unit, to avoid confusing with the unit of measurement. I removed the definition regarding chemical properties, I believe it's kind of tautological, since the definition of chemical property is built around the concept of atoms.

Finally I have added a source in Spanish from my university, all changes strictly follow the source, it's not in the ideal language, so if someone can find an equivalent source in english to replace or complement it with, that would be appreciated. Thank you. Tomás Zubiri, Buenos Aires, Argentina - July 2020