Sodium Element in Periodic table (Info + Why in Period 3?)

Sodium(Na) element in Periodic table (Electron configuration, Atomic mass, Atomic number, Symbol, Valence electrons)

This is a SUPER easy guide on sodium element.

In fact, the table mentioned below is the perfect information box (Which gives you every single detail about the Sodium element in Periodic table.)

So if you want to know anything about Sodium element, then this guide is for you.

Let’s finish this very quickly.

Sodium Element (Na) Information

Appearance of Sodiumappearance of sodium
Silvery white
State of Sodium at STPSolid
Position of Sodium in Periodic tableposition of sodium in periodic table
Group: 1, Period: 3
Block: s
Category of Sodium elementCategory of sodium element
Alkali metals
Atomic number of Sodium, or 
Protons in Sodium
Neutrons in Sodium12
Electrons in Sodium11
Symbol of SodiumNa
Atomic mass of Sodium22.990 u
Electrons arrangement in Sodium 


Bohr model of Sodium
Bohr model of sodium (Electrons arrangement in sodium)
2, 8, 1
Electronic configuration of Sodium[Ne] 3s1
Atomic radius of Sodiumatomic radius of sodium
227 picometers (van der Waals radius)
Valence electrons in SodiumValence electrons in sodium (Na)
1st Ionization energy of Sodium5.139 eV
Electronegativity of Sodium0.93 (Pauling scale)
Crystal structure of Sodiumcrystal structure of sodium
BCC (Body Centered Cubic)
Melting point of Sodium370.9 K or 97.7 °C or 208 °F
Boiling point of Sodium1156 K or 882.9 °C or 1621.2 °F
Density of Sodium0.97 g/cm3
Main isotope of Sodium23Na
Who discovered Sodium and when?who discovered sodium and when
Sir Humphry Davy in 1807
CAS number7440-23-5

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Sodium in Periodic table

Sodium element is in group 1 and period 3 of the Periodic table. Sodium is the s-block element and it belongs to alkali metals group.

H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac** Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
*Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
**Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

Why is Sodium in Group 1 and Period 3 of the Periodic table?

Sodium is in group 1 because it has 1 valence electron.
Sodium is in period 3 because it has 3 shells or orbits.

Why is Sodium in Group 1 and Period 3 of the Periodic table

Now I’ll explain to you the perfect detailed reason why sodium is in group 1, why it is in period 3 and also why it is in s-block?

Let’s see the reasons one by one.

Why is Sodium in Group 1?

Why is Sodium in Group 1

Do you know, how many electrons can be accommodated in the first shell, second shell, third shell, fourth shell, etc…?

Here is the table showing the capacity of orbits to hold electrons. 

Number of electrons in shells.

Orbit / Shell (n)Maximum no. of electrons this orbit can hold
K shell, n = 12 × 1² = 2
L shell, n = 22 × 2² = 8
M shell, n = 32 × 3² = 18
N shell, n = 42 × 4² = 32


  • 1st shell can hold 2 electrons.
  • 2nd shell can hold 8 electrons.
  • 3rd shell can hold 18 electrons.
  • 4th shell can hold 32 electrons.

Now the atomic number of Sodium (Na) is 11.

Hence sodium element has the electrons arrangement 2, 8, 1.

This electron arrangement indicates that the outermost orbit of Sodium (Na) has 1 electron.

Hence, it lies in group 1.

Why is Sodium in Period 3?

Why is Sodium in Period 3

Let me ask you a question.

How many shells does sodium have?

It’s 3. Right? 

You have already seen the bohr model of sodium element in the above table.

From the Bohr model, it can be found that the number of orbits or shells in sodium is 3.
Hence, as sodium has 3 orbits, it lies in period 3 of the Periodic table. 

Why is Sodium in s-block?

Why is Sodium in s-block

Before knowing this reason, first of all a simple question to you.

How can you determine the blocks wise position of elements?

The simple answer: The elements will lie in the s, p, d or f block will completely depend upon the subshell in which the last electron will enter.

For example; the electron configuration of Sodium is [Ne] 3s1

So the last electron of Sodium enters the s-subshell or s-orbital. 

Hence, sodium is the s-block element.

Is Sodium a Metal or Nonmetal?

Yes, Sodium is a Metal. It’s a silvery white colored reactive metal. It is a soft metal and it can be cut even by using a kitchen knife. It is a light metal and it even floats on water.

Is Sodium a Metal or Nonmetal

But do you know what exactly the metals are?

  • Metals are the elements which lose electron/s during a chemical reaction. 

In other words, metals are electron donors.

what are metals

Metals are found on the left side of the Periodic table.

For more clarification, see the location of metals on the Periodic table (Image).

Why Sodium catches fire in water?

sodium in water reaction

It seems very dangerous. Isn’t it?

Let me explain the reasons why sodium catches fire in water. 

Or in other words, why is sodium a very reactive metal?

The reasons are;

  1. Large atomic size
  2. One valence electron
  3. Weak metallic bonds

Let me tell you few things about these three reasons (very quickly).

1). Large atomic size

Sodium element is in group 1, and group 1 elements have the larger atomic radius compared to elements of other groups.

Due to larger atomic radius, they have a weak attractive force for the outermost electron.

why is sodium reactive

And due to weak attractive force, the outermost electron gets easily escaped during a chemical reaction. 

Hence sodium metal reacts vigorously with the water and it even catches fire.

2). One valence electron

sodium (Na) valence electrons (Bohr diagram)

The sodium atom have only one electron in outermost orbit. This electron gets easily lost or shared during a chemical reaction.

Hence due to rapid losing of electrons, the sodium metal is highly reactive. 

3). Weak metallic bonds

You know that sodium is a metal, but the fact is that it has weak metallic bonds.

In other words, the attractive force among the sodium atoms is weak.

In short sodium element has less intermolecular force of attraction. 

Due to less intermolecular force of attraction, it loses electrons very easily and hence it reacts with water very fast. 

Also see: Why sodium is called alkali metal?

I hope you have understood the reason why sodium is very reactive to water.

Now let’s move to another interesting question. 

Why Sodium gives yellow flame on heating?

sodium flame test yellow color

When sodium metal is heated with a flame, its outermost electron gets excited onto a higher energy level.

When this excited electron loses its energy, it again comes back to the lower energy level.

During this phenomenon, it emits an electromagnetic radiation having a wavelength of around 589 nm.

This emitted radiation of 589 nm is nothing but a visible golden yellow light.

Hence, sodium gives golden yellow flame when it is heated.

Why Sodium floats on water?

Why Sodium floats on water

You might have studied the concept of density in physics.

By knowing the density of two objects, we can come to know which object will float and which will sink in water.

If the object has a density higher than the water, then it will sink. And if the density of object is less than the water, then it will float on water.

Now let’s see about sodium metal and it’s density.

Sodium has a density of 0.97 g/cm3, while water has a density of 1 g/cm3.

That means sodium metal is less dense than water.

Because of this reason, the sodium metal floats on water. 

8 Interesting facts about Sodium

Here are the interesting facts about Sodium element.

  • Sodium is a soft metal and it can be cut even by using a kitchen knife. 
  • Sodium metal is silver white in color when it is freshly cut, but it suddenly forms an oxide layer if kept open in air.
  • Sodium metal is lighter than water, hence it floats on water.
  • Sodium burns with a golden yellow flame when it is heated. 
  • Sodium element is also essential to maintain the fluid balance in the cells of our body. 
  • Around 2.6% of the Earth’s crust contains sodium metal. Out of all alkali metals, Sodium is most abundant. 
  • In nature, Sodium never exists as a pure metal because of its high reactivity. It is always found in a compound form with other elements.

Sodium has many isotopes, out of which only one isotope is most stable (i.e 23Na).

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Chemical data: Chemspider, wikipedia
Sodium element image: Image by Dnn87,CC BY-SA 3.0, via Wikimedia Commons
Sir Humphry Davy: Thomas Phillips , Public domain, via Wikimedia Commons
Sodium yellow flame: Image by Der Messer, CC BY-SA 3.0, via Wikimedia Commons

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