The Importance And Atomic Number Of First 20 Elements

Every element of the periodic table has its own story and is often used in several industries. Although every element in the periodic table is important, few can be used at normal conditions, as most are very reactive. 

Thus, only some elements from the first 30 elements of the periodic table are used very commonly around us. The following is a description of atomic numbers followed by a list of the first 20 elements with atomic numbers that are primarily used in industries and are a part of our daily lives.


In the 19th century, the atomic theory was the first modern theory proposed by John Dalton. He is known as the father of atomic theory. Before him, the Greek philosopher Leucippus and Demokritos too came up with the theory of atoms. Later in 1910, a researcher named Henry Gwyn Jeffreys Moseleys introduced the concept of atomic number. 

What Are Atomic Numbers

An atomic number of any element is defined by the total number of protons present in its nucleus. An element is distinct from others due to its atomic number. For example, the atomic number of carbon is six because there are 6 protons present in carbon, whereas chlorine has 17 atomic numbers because of 17 protons in its nucleus. The atomic number is often denoted by Z.

Atomic number = Number of proton = Number of electron = Z

In the modern periodic table, the elements are arranged in increasing order of atomic number with the increase in mass number. 

In a specific element, all the atoms have an equal number of protons; due to this, the atomic number is the same. In comparison, atoms of different elements have different atomic numbers. 

Every individual atom of an element consists of electrons, protons and neutrons. The valency of a certain element is calculated by the number of electrons left in the outermost shell of an atom after arranging them according to electronic configuration. Both atomic and mass numbers of atoms are associated with the number of protons and neutrons in the nucleus. 

List Of First 20 Elements With Their Atomic Numbers

Symbol  Atomic number Name of the element Atomic mass (amu, g/mol)
H 1 Hydrogen 1.0079
He 2 Helium 4.0026
Li 3 Lithium  6.941
Be 4 Beryllium  9.0121
B 5 Boron  10.8
C 6 Carbon  12.01
N 7 Nitrogen  14.006
0 8 Oxygen  15.999
F 9 Fluorine  18.9984
Ne 10 Neon  20.179
Na 11 Sodium  22.989
Mg 12 Magnesium  24.30
Al  13 Aluminium  26.981
Si  14 Silicon  28.08
15 Phosphorous  30.973
16 Sulphur  32.06
Cl  17 Chlorine  35.45
Ar  18 Argon  39.94
19 Potassium  39.098
Ca  20 Calcium  40.08


Significance Of Atomic Number

In the modern periodic table, the atomic number of any element tells us about the position of elements and their valency. The elements in the same group have similar chemical properties due to the same number of electrons left in their outermost shell, i.e., similar electronic configuration. 

The atomic number gives us the exact information about all the elements, whereas atomic mass does not. The atomic number determines both physical and chemical properties. 

Importance Of First 20 Elements 

There are several properties and significance of all the first 20 elements in the periodic table. Let us see the following list of the first 20 elements with their properties and importance. 

  1. Hydrogen – It is an odourless and colourless element. Hydrogen is a flammable and explosive gas that is used to make ammonia for fertilisers.
  2. Helium – Helium, a non-metallic element, is a colourless and odourless gas. It is considered much lighter than air and thus used in blimps and balloons.
  3. Lithium – Lithium is mainly used in phones, laptops and digital cameras.
  4. Beryllium – A grey metallic element used as a reflector and moderator in nuclear reactions. This is because Beryllium has less absorption capacity. 
  5. Boron – Its metallic form is tough, and it is a poor conductor of electricity. Boron is used as a rocket fuel igniter.
  6. Carbon – Mainly useful in metal smelting. It is a non-metallic chemical element that constitutes almost every living object.
  7. Nitrogen – This is a neutral colourless gas, which is used in fertilisers. 
  8. Oxygen – This element is a colourless and odourless gas, essential for respiration and also enables combustion. It is also found in abundance in the earth’s atmosphere. 
  9. Fluorine – It is a gaseous element that is poisonous and has a pale yellow colour. It is used in nuclear energy industries.
  10. Neon – Neon is a colourless gas element and is used in advertisement lights and signs.
  11. Sodium – An element with a silver colour, which is highly reactive, is sodium. It is a soft metal that merges with chlorine to make table salt. 
  12. Magnesium – It is a silvery metallic element in group 2, which is widely used in firecrackers.
  13. Aluminium – A light metallic element used in the manufacture of aeroplanes, parts of buildings and pots etc.
  14. Silicon – It is a metalloid element that is mostly used in electronics components and glass compounds.
  15. Phosphorus – Phosphorus is a non-metallic element that is present in sulphate minerals. It is primarily used in the manufacture of safety matches. 
  16. Sulphur – This yellow colour non-metallic element is often used to make sulphuric acid and medicines like pet powders.
  17. Chlorine – An element that is used in bleach and in chemicals used to kill germs in the water. It’s a halogen and has a greenish-yellow colour.
  18. Argon – It is a noble gas, which is used to produce reactive elements. Welders use argon while welding.
  19. Potassium – Potassium is a silver metallic element that occurs in seawater and is also used in fertilisers.
  20. Calcium – A grey colour soft metallic element used as a getter in vacuum systems.

Final Remarks

The atomic number is an essential part of chemistry, as it is used to determine the right position of an element in the periodic table. Moreover, the information about electronic configuration provided by the atomic number helps scientists predict the nature of an element. 

The aforementioned properties and uses of all the elements tell us how the properties of an element is a function of its atomic number.


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