Top 9, Elements, symbol, atomic number & valency

Elements, symbol, atomic number & valency

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Elements 

• Definition:-
• A substance that cannot be broken down into simpler substances by chemical means is called an element.
• A pure substance made up of only one kind of atom that can't be split up into two or more substances is called an element.

Atomic number 
The number of protons (p) or electrons (e) present in an atom is called its atomic number.

• Valency 
• Definition: The combining capacity of an element is called its valency.
• For completion of template or octate when an element gives or accepts an electron are called its valency.

Duplate state
An atom can achieve a stable electronic configuration if it has two electrons in its outermost shell is called duplicate state.

 
Electronic configuration
The distribution of an electron in an orbit is called electronic configuration.

Ex. Sodium  2,8,1

🎷 While doing a basic study of elements, you should know the elements with atomic numbers one to twenty and their names.


 Elements     At .no     valency 
1.Hydrogen         H               1
2. Helium            HE            --
3. lithium              LI             1
4. Beryllium         Be            2
5.boron                 B             3
6. carbon               C            4
7. nitrogen            N            3
8. Oxygen              O            2
9. Fluorine             F              1
10. neon                Ne           --
11. sodium            Na             1
12. magnesium    Mg            2
13. aluminium     Al              3
14. silicon              Si             4
15Phosphorus      P             3 & 5
16. Sulphur           S              2
17. chlorine          Cl               1
18.Argon                Ar           --
19. potassium       P               1
20. calcium           Ca           2


Here 1 to 20 serial numbers are also atomic numbers of those atoms.

After studying the first twenty elements we need knowledge of some elements, their names, and their symbol.


Elements   symbol.    Valency 

manganese.       Mn           2
iron                      Fe.      2&3
Cobalt                  Co           2
Nickel                  Ni            2
copper                 Cu       1&2
Zinc                      zn           2
bromine              Br               1
Silver                   Ag               1
tin                         Sn
iodine                   I                 1
tungsten.             W
Gold                     Au
Mercury              Hg        1&2

There is no need to remember valencies of some elements and their electronic configuration.

  🥁 We must know some inert gas elements like Helium (He), Neon (Ne), and Argon (Ar) along with some more elements.
Krypton Kr
Xenon Xe
Radon Rn

 🪇 We have seen the elements Boron (B) and silicon (Si), but along with that, we should come across some metalloid elements and their names.
Germanium Ge
Antimony Sb
Tellurium Te
Polonium Po

• Definition: Elements that show the properties of metals and non-metals are called metalloids.
• These elements separate the metals on the left from the nonmetals on the right. 

🎸 Group 1 includes Hydrogen, Lithium, Sodium, Potassium, Cesium Cs, and Francium (Fr). These elements are called alkali metals.



🎻 Group 2 includes beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).
 Elements in group 2 are called alkaline earth metals.

Elements in group 17 are called halogen elements. Because these elements form acids when they react chemically with hydrogen.
Ex: Fluorine (F), Chlorine (Cl), Bromine (Br) Iodine (I), Statin (At) 

🎺 The elements that show valency three are boron (B) and aluminum (Al).


😊 The elements that show valency four are carbon (C) and silicon (Si). 

Some element shows more than one valency they are called elements with variable valencies.

Ex.
1.Copper (Cu),  Cu+ --> Cuprous                                Cu++ --> Copper

2. Mercury (Hg) 
                  Hg+ --> Mercurius
                  Hg++ --> Mercuric

3. Iron (Fe). Fe++ --> Iron
                      Fe+3 --> ferric 
             
4. Tin (Sn): Tin element shows  transition/ variable valency like +2, +4

🎄 A radioactive element

• Some elements have the property of emitting invisible, very penetrating, and high-quality radiation/rays, called radioactive elements.
• Generally, elements of atomic number 82 to atomic number 92 are found in nature spontaneously emitting radiation. This is called natural radiation.
• Ex: Uranium (U), Thorium (Th), Radium 

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