Editing Atomic number

== What is Atomic Number? ==
The [[Atomic number| atomic number]] of a [[Elements]] is the number of [[Proton|protons]] found in the nucleus of an atom of that element. It is denoted by the symbol '''Z'''.

Each element has a unique [[Atomic Number]], which determines its identity and position in the [[Periodic Table of Elements]].

== Definition ==
<blockquote>
''Atomic Number (Z) = Number of Protons in the Nucleus''
</blockquote>

* For example, all [[Hydrogen]] atoms have 1 proton, so the [[Atomic Number]] of hydrogen is [[1]].
* [[Carbon]] has 6 protons, so its atomic number is [[6]].
* [[Oxygen]] has 8 protons, so its atomic number is [[8]].

== Role of Atomic Number ==
The [[Atomic Number]] plays a central role in modern [[Chemistry]]:

* It [[Identifies Elements|defines the element]] – no two elements share the same [[Atomic Number]].
* It determines the arrangement of elements in the modern [[Periodic Table]].
* It influences an atom’s [[Chemical Properties|chemical properties]], [[Electron Configuration|electron configuration]], and place in the [[Periodic Trends|periodic trends]].
* In a neutral atom, the number of [[Electrons|electrons]] equals the number of [[Protons|protons]] (i.e., the [[Atomic Number]]).

== Discovery of Atomic Number ==
Although early scientists like [[Dmitri Mendeleev]] arranged elements by [[Atomic Mass]], inconsistencies in the [[Periodic Table]] were only resolved when British physicist [[Henry Moseley]] introduced the concept of [[Atomic Number]] in 1913.

Using [[X-ray Spectroscopy]], Moseley discovered that each element emits radiation at a frequency directly related to the number of [[Protons]] in its nucleus.

This led to the modern [[Periodic Law]]:
<blockquote>
''The properties of elements are a periodic function of their atomic numbers.''
</blockquote>

== Examples of Atomic Numbers ==
{| class="wikitable"
|+ Selected Elements and Their Atomic Numbers
! Element !! Symbol !! Atomic Number
|-
| [[Hydrogen]] || H || 1
|-
| [[Helium]] || He || 2
|-
| [[Carbon]] || C || 6
|-
| [[Oxygen]] || O || 8
|-
| [[Iron]] || Fe || 26
|-
| [[Gold]] || Au || 79
|-
| [[Uranium]] || U || 92
|-
| [[Oganesson]] || Og || 118
|}

== Difference Between Atomic Number and Mass Number ==
* [[Atomic Number]] (Z): Number of [[Protons]]
* [[Mass Number]] (A): Total number of [[Protons]] + [[Neutrons]]

Example:  
[[Carbon-12]] → Atomic number = 6, Mass number = 12  
So, neutrons = 12 − 6 = 6

== Atomic Number and Isotopes ==
[[Isotopes]] are atoms of the same element (same [[Atomic Number]]) but with different numbers of [[Neutrons]].

* Example: [[Hydrogen]] has three isotopes:
** [[Protium]] (¹H), [[Deuterium]] (²H), and [[Tritium]] (³H) – all have [[Atomic Number]] 1

== Importance in Chemistry and Physics ==
The [[Atomic Number]] is essential for:

* Identifying elements
* Understanding [[Chemical Behavior]]
* Predicting [[Reactivity]] and [[Bonding]]
* [[Nuclear Physics]] and [[Radioactivity]]

== See Also ==
* [[Periodic Table of Elements – A Complete Guide]]
* [[Chemical Elements – A Complete Guide]]
* [[Dmitri Mendeleev – The Father of the Periodic Table]]
* [[Henry Moseley – The Scientist Who Defined Atomic Number]]

== References and Further Reading ==
* [https://iupac.org/ International Union of Pure and Applied Chemistry (IUPAC)]
* [https://www.khanacademy.org Khan Academy – Atomic Structure]
* Standard [[Chemistry]] Textbooks (NCERT, Oxford, Pearson)

== Disclaimer ==
''This article is written for [[Academic]] and [[Educational Purposes]] only. It is intended to provide a clear explanation of the [[Atomic Number]] for students and educators using MediaWiki platforms. For advanced study, consult official scientific publications and curriculum-based textbooks.''