Electronic Configuration of Elements

Initially, atoms were thought to be indivisible. The word ‘atom’ is derived from the Greek word ‘atmos’, which means indivisible. However, in the late eighteenth century scientists like Rutherford and E Goldstein discovered subatomic particles, which made the idea of indivisibility of atoms invalid.

Today, we know that atoms are actually composed of subatomic particles. There are three kinds of subatomic particles-protons, neutrons and electrons. The protons are positively charged particles, while electrons are negatively charged. The neutrons have no net charge on them. The protons and neutrons are located in the centre of the atom, a region known as the nucleus. The protons and neutrons are collectively known as nucleons. They are pretty immobile and don’t move around much. The electrons, on the other hand, constantly jump around and are very much mobile. They are very uniquely arranged in the energy levels around the nucleus. This arrangement is pretty unique to every element. This arrangement of electrons is referred to as the electronic configuration of the said element.

Electronic Configuration

The atom is like a family of protons, neutrons and electrons. They are all together by attractive forces. But, like every other family, they also have certain traits that repulse them and keep them apart. This love-hate relationship is what makes the study of atoms quite interesting. For instance, particles with opposite charges, like protons and electrons attract each other. However, particles with like charges repel each other. Proton-proton repel each other, electron-electrons repel each other. The neutrons are kinda boring. They are quite literally ‘neutral’.

Scientists have devised a way of writing the arrangement of electrons around the nucleus of an atom. This arrangement is called electronic configuration. 

Electrons are arranged according to their energy level in various shells. The shells with the lowest energy are filled first. Each energy level or shell is also called orbit. These are denoted by the letter ‘n’. Each orbit can hold a maximum of 2n2electrons where n is the shell number. Each shell also consists of sub-shells, known as orbital. These help to precisely pinpoint the location of electrons. These are denoted by the letters ‘s’, ‘p’, ‘d’ and ‘f’. If shells are the apartment buildings, the subshells are the flat numbers. 

The subshells fill up electrons with varying capacities. The subshell ‘s’ can hold up to 2 electrons. The next orbital ‘p’ can hold up to 6 of these particles. The next shell ‘d’ has an occupancy for 10 electrons, while the orbital ‘f’ can hold up to 14 electrons.

For example, the electronic configuration of the element hydrogen is 1s1. Here, the number ‘1’ denotes the shell and the letter ‘s’ denotes the sub shell. The superscript ‘1’ denotes the number of electrons in the given subshell.

Electronic Configuration of Elements

There are 118 elements, known to humans. These have been enlisted in a little cheat sheet, also known as the periodic table.

The number of protons of an element is denoted by the atomic number of the element.  Generally, under normal circumstances, the number of protons of an atom is equal to its number of electrons. Hence, the number of protons also gives an idea of the number of electrons of an atom. The electronic configuration of the element describes the arrangement of these electrons in an atom.

The following is the list of all elements with their electronic configuration:

Here, in these images, the electronic configuration of all elements has been given. For the purpose of convenience, some of the electronic configurations can also be written, starting with the symbols of certain noble gases. This denotes the electronic configuration of that particular noble gas since it is identical to that part of the electronic configuration of that element. For example, the electronic configuration of lithium (Li) is given as [He]2s1. The full electronic configuration of lithium is 1s22s1. The first part of the electronic configuration (1s2)is identical to the electronic configuration of helium (He). Hence, the symbol of helium has been used in the electronic configuration of lithium.

Electronic Configuration of ‘d’ Block Elements

The periodic table is a collection of rows and columns. The rows of the periodic table are referred to as ‘periods’, while the columns of the periodic table are called ‘groups’. The periodic table has also been divided in ‘blocks’ on the basis of orbitals of electronic configuration. 

The electrons which are found in the central region of the periodic table, from group 3 to group 12 are referred to as the ‘d block elements’. These elements have partially filled d orbitals. These elements are also known as transition elements.

The d-block elements have been divided in series based on the penultimate shell in which the valence electrons fill in.

• 3d series of d-block elements

1. Scandium (Sc)- [Ar]3d14s2

2. Titanium (Ti)- [Ar]3d24s2

3. Vanadium (V)- [Ar] 3d34s2

4. Chromium (Cr)-[Ar]3d54s1

5. Manganese (Mn)-[Ar]3d54s2

6. Iron (Fe)-[Ar]3d64s2

7. Cobalt (Co)-[Ar]3d74s2

8. Nickel (Ni)-[Ar]3d84s2

9. Copper (Cu)-[Ar]3d104s1

10. Zinc (Zn)-[Ar]3d104s2

• 4d series of d-block elements

1. Yttrium (Y)-[Kr]4d15s2

2. Zirconium (Zr)-[Kr]4d25s2

3. Niobium (Nb)-[Kr]4d45s1

4. Molybdenum (Mo)-[Kr]4d55s1

5. Technetium (Tc)-[Kr]4d65s2

6. Ruthenium (Ru)-[Kr]4d75s2

7. Rhodium (Rh)-[Kr]4d85s1

8. Palladium (Pd)-[Kr]4d105s0

9. Silver (Ag)-[Kr]4d105s1

10. Cadmium (Cd)-[Kr]4d105s2

• 5d series of d-block elements

1. Lanthanum (La)-[Xe]5d16s2

2. Hafnium (Hf)-[Xe]4f145d26s2

3. Tantalum (Ta)-[Xe]4f145d36s2

4. Tungsten (W)-[Xe]4d145d46s2

5. Rhenium (Re)-[Xe]4f145d56s2

6. Osmium (Os)-[Xe]4f145d66s2

7. Iridium (Ir)-[Xe]4f145d76s2

8. Platinum (Pt)-[Xe]4f145d86s1

9. Gold (Au)-[Xe]4f145d96s1

10. Mercury (Hg)-[Xe]4f145d106s2

• 6d series of d-block elements

1. Actinium (Ac)-[Rn]6d17s2

2. Rutherfordium (Rf)-[Rn]5f146d27s2

3. Hahnium (Ha)-[Rn]5f146d37s2

4. Seaborgium (Sg)[Rn]5f144d47s2

5. Bohrium (Bh)-[Rn]5f146d57s2

6. Hassium (Hs)-[Rn]5f146d67s2

7. Meitnerium (Mt)-[Rn]5f146d77s2

8. Ununnilium (Uun)-[Rn]5f146d87s2

9. Unununium (Uuu)-[Rn]5f146d107s1

10. Ununbium (Uub)-[Rn]5f146d107s1

Conclusion

Atoms are the basic building blocks of matter. They consist of subatomic particles. There are three kinds of subatomic particles-protons, neutrons and electrons. The protons and neutrons are located in the nucleus of the atom while the electrons revolve around the nucleus. The arrangement of electrons around the nucleus is called electronic configuration.