# Periodic Table

Simple+
English

An element, as any scientist knows, is a substance that cannot be chemically interconverted or broken down into simpler substances and are primary constituents of matter. Ancient philosophers and observers of the universe identified the elements as earth, water, air and fire. From our modern understanding, natural abundances of iron, gold, silver, lead, tin, mercury, sulfur and carbon are the very first known elements used to build civilization. Other elements are hiding in mixtures and compounds which could not easily be extracted or purified. Early chemist classified them by their properties and characteristics, subsequently discovering many more (and the way to purify and extract, even synthesize them) with nearly all of the naturally-occuring elements having been discovered by 1900.

One man shed light on the structure and relationships of the the elements by ordering them in a table and sorting them. Dmitri Ivanovich Mendeleev (Дми́трий Ива́нович Менделе́ев) (1834-1907) published his formulation in 1869 to correct the properties of elements and to aide int he prediction of the properties undiscovered elements. This work is known now as the Periodic Table of Elements .

Source: wikipedia

### Periodicity Of Elements

The essential model or theory to understand an elements chemical properties came from the early birth of quantum mechanics and is known as electron configuration. The element is modeled as an atom with its "number", the atomic number ( Z ) which represents the number of protons, and therefore the number of electrons as well( in ground state ). The periodicity of the elements might be explained by the electron structure of the atom which can in turn be explained by quantum theory.

An electron within the atom can be described by the four quantum numbers:

• n    = the principal quantum number( or simply, quantum number ), e.g: 1,2,3…
• l     = the orbital quantum number( or simply, angular number ), e.g: 0,1,2…
• m l = the orbital magnetic quantum number( or simply, magnetic number ), e.g: -2,-1,0,+1,+2…
• m s = the spin magnetic quantum number( or simply, spin number ), e.g: ⁺½ or ⁻½.
The four quantum numbers designate specific levels, orbitals, magnetics, and spins of electrons . This explains that they are describing the detailed characteristic of the electrons in the atom. The principal quantum number n describes the energy level of the electron shell. When value of n is higher, the number of principal electron shell is greater, which means a greater distance between the farthest electron and the atoms nucleus. As a result the size and radius of the atom increases. The angular quantum number l describes the shape of the orbital. Each quantum number is composed of one or more subshells( orbital ). The detail of possible subshells are shown in following table:

Orbital label l Max electrons Spectroscopic Name
s 0 2 Sharp
p 1 6 Principal
d 2 10 Diffuse
f 3 14 Fundamental
g 4 18 ( simply in alphabet after f )
h 5 22
i 6 26

The magnetic quantum number describes the number of orbitals and its orientation in the space of a specific orbital. Consequently, its value depends on the orbital angular momentum quantum number l. The possible value of m l is an interval ranging from -l to +l, so it may be zero, a negative integer, or a positive integer. Unlike n, l, and m l , the spin magnetic quantum number does not depend on another quantum number. It defines the direction of the electrons spin , which value may have ⁺½ (represented by ↾ "spin up") or ⁻½(represented by ⇃ "spin down.")
So far we have explanations for the four quantum numbers that model an elemental atom.

### Principles

There are principles that must be followed when writing electron configuration; these principles are described below:
• #### Pauli Exclusion Principle or Quantum State

This principle states that:
There are no two electrons in an atom can exist in the same quantum state .
Because the state of any electron is specified by the quantum numbers n, l, m l and m s , the principle simply states that no two electron can have the same set of the four quantum numbers .
• #### Aufbauf Principle or Constructing Up Principle

states that:
A maximum of two electrons are put into orbitals in the order of increasing orbital energy: the lowest-energy orbitals are filled before electrons are placed in higher-energy orbitals.
• #### Klechkowski's Rule or Occupation of Orbital

states that:
• Orbitals are filled in the order of increasing n+l.
• Where two orbitals have the same value of n+l, they are filled in order of increasing n
One of the way to remember this rule is, to make a table like the one below and use vertical lines to determine which subshells correspond to each other.
Source: wikipedia
• #### Hund's Rule or Pairing Rule

states the following:
Pairing of electrons take place when all the available degenerate orbitals in a given subshell are filled with one electron each.
Orbitals may have identical energy levels when they are of the same subshell (l = 1, then m l are -1, 0, 1, which have similar energy). Then when assigning electrons in orbitals, each electron will first fill all the orbitals with similar energy (read: degenerate orbitals) before pairing with another electron.

### Noble Gas Notation

Noble Gas Notation takes a slightly different form as seen here:
[closest noble gas element] [ quantum number ][ orbital name ] [ number of electrons ]

Here are some samples (Noble Gasses are located in column 18 (IUPAC),) described below:
Element Symbol Atomic Number( Z ) Electron Configuration Noble Gas Notation
Helium He 2 1s² 1s²
Neon Ne 10 1s² 2s² 2p⁶ [He] 2s² 2p⁶
Argon Ar 18 1s² 2s² 2p⁶ 3s² 3p⁶ [Ne] 3s² 3p⁶
Krypton Kr 36 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ [Ar] 3d¹⁰ 4s² 4p⁶
Xenon Xe 54 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ [Kr] 4d¹⁰ 5s² 5p⁶
and so on…

### Writing Electron Configuration

Electron configuration follows this form:
[ quantum number ][ orbital name ] [ number of electrons ]

When writing the electron configuration, we must first write the energy level ( quantum number ) then the subshell (orbital number) and the superscript , which is the number of electrons in that specific subshell. Using these rules , we can now start writing the electron configuration for all the elements in the periodic table.

Consider the following element, Oxygen(O) with Z = 8:
 Element: Oxygen Symbol: O Z: 8 Orbital Diagram: ⇅  ⇅   ⇅↾↾ Orbital Model: 2      2      2    1    1 Electron Configuration: 1s²    2s²      2p⁴ Noble Gas Notation: [He] 2s² 2p⁴

### CheckiO Quantum Task

Your task is to determine the atomic number and electron configuration in the noble gas notation as well as its orbital model , which is 0 - if there are no electrons, 1 - if the electron is in a degenerate orbital, and 2 - for electrons in a full orbital, by its symbolic element. The number of elements is limited to 118 (as of September First, 2013). This task will use superscript for the electron notation, as seen below:
Unicode superscript characters
Unicode 0 1 2 3 4 5 6 7 8 9
U+00Bx
U+207x x⁰ x⁴ x⁵ x⁶ x⁷ x⁸ x⁹

Input data: A string, which is not case sensitive, the symbol of the element

Output data: A list containing the atomic number, configuration notation and orbital model.

Example:

```assert( checkio( 'H' ) == [ "1", u"1s¹", "1" ] ), "First Test - 1s¹"
assert( checkio( 'He' ) == [ "2", u"1s²", "2" ] ), "Second Test - 1s²"
assert( checkio( 'Al' ) == [ "13", u"[Ne] 3s² 3p¹", "2 2 222 2 100" ] ), "Third Test - 1s² 2s² 2p6 3s² 3p¹"
assert( checkio( 'O' ) == ["8", u"[He] 2s² 2p⁴", "2 2 211"] ), "Fourth Test - 1s² 2s² 2p⁴"
assert( checkio( 'Li' ) == [ "3", u"[He] 2s¹", "2 1" ] ), "Fifth Test - 1s² 2s¹"

print('All done!')
```
Settings
Code:
Other:
Invalid hot key. Each hot key should be unique and valid
Hot keys:
•  to Run Code: to Check Solution: to Stop:
CheckiO Extensions

CheckiO Extensions allow you to use local files to solve missions. More info in a blog post.

In order to install CheckiO client you'll need installed Python (version at least 3.8)

Install CheckiO Client first:

`pip3 install checkio_client`

Configure your tool

`checkio --domain=py config --key=`

Sync solutions into your local folder

`checkio sync`

(in beta testing) Launch local server so your browser can use it and sync solution between local file end extension on the fly. (doesn't work for safari)

`checkio serv -d`

Alternatevly, you can install Chrome extension or FF addon

`checkio install-plugin`
`checkio install-plugin --ff`
`checkio install-plugin --chromium`

Read more here about other functionality that the checkio client provides. Feel free to submit an issue in case of any difficulties.

Pair Programming (Beta-version)

Welcome to Pair Programming! Engage in real-time collaboration on coding projects by starting a session and sharing the provided unique URL with friends or colleagues. This feature is perfect for joint project development, debugging, or learning new skills together. Simply click 'Start Session' to begin your collaborative coding journey!

Waiting for Pair Programming to start...

You are trying to join a pair programming session that has not started yet.

Please wait for the session creator to join.

Waiting for Pair Programming to reconnect...

It looks like the creator of the pair programming session closed the editor window.

It might happen accidentally, so that you can wait for reconnection.