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The Atom

February 23, 2012

The structure of atoms and the arrangement of the periodic table are intimately linked. Trying to blog the characteristics of the elements without an explanation of how all atoms are structured is becoming impossible so… Think of this as a blue print of the atom – but drawn with a crayon, gripped chimp-like in my left hand.

The Duplo kit for building atoms would contain only three types of building blocks.


The number of proton defines the identity of the atom (which element in the periodic table).

Each proton has a charge of +1 and an atomic mass of 1. Protons are found in the centre of an atom in the nucleus and absolutely hate being held so close to each other. Imagine having several magnets and trying to push all the north poles together in a very very small space – this is how reluctant protons are to be near each other only more so. Neutrons are included in the nucleus to mediate the situation. The more protons you have the more neutrons are needed to stop the protons splitting off from the main group (radioactive decay).


The UN peacekeepers of the subatomic world.

Each neutron has a mass almost the same as the proton. As their name suggests neutrons are completely neutral so the number included in the nucleus of the atom will have no influence on the identity of the atom and little impact on its personality. This is how hydrogen can have none, one or two neutrons in its nucleus and still be hydrogen and behave almost exactly the same even if it has put on a bit of weight.


Give atoms their personality.

Electrons are light and fast moving but trapped on a fixed path orbiting around the nucleus (think hamster in a wheel). Electrons have a charge of -1 so the number of electrons equals the number of protons to give an atom with no overall charge. If the atom (beryllium) has four protons (+4) it will have four electrons (-4) in what is technically called the zero oxidation state – Be(0).

More than one hamster on a wheel is ridiculous so things need to be organised. Electrons are arranged into shells and subshells in a 2, 2 + 6, 2 + 6, 2 + 10 + 6, 2 + 10 + 6,…. pattern. If you read the periodic table from left to right as you would words in a book, starting from hydrogen you will see that the number of elements in each block matches the pattern of electrons in shells. This is not a coincidence.

For example, …

Hydrogen – 1 electron – 2 wheels, 1 hamster

Helium – 2 electrons – 2 wheels, 2 hamsters running in opposite directions. Symmetrical and even – this is a complete shell.

Lithium – 3 electrons – 2 wheels, 2 hamsters running in opposite directions; 2 bigger wheels, 1 hamster. A wheel without a hamster is a sad sight so lithium will readily give away its outermost hamster (electron) to obtain a complete shell of hamsters and wheels.

Beryllium – 4 electrons – 2 wheels, 2 hamsters running in opposite directions; 2 bigger wheels, 2 hamsters running in opposite directions.

And so on and so on…… This arrangement of wheels and hamsters is called the ‘Pauli Exclusion Principle’ – use it in conversation, impress your friends.

All atoms are aiming for an ideal number of electrons 2, 10, 18, 36, 54 etc. as this number gives full outer shells like the enviable Noble gases. To achieve this atoms towards the left side of the periodic table will give electrons away to reach one of the magic numbers (for example, sodium with 11 electrons will give away one to reach the happy number 10). Elements to the right of the periodic table will take electrons (fluorine will steal one electron to make up a total of 10) and elements in the middle will share with other atoms to give the outward appearance of completeness.

The by-product of all this electron swapping and sharing is chemical bonds and molecules or compounds and an entire scientific discipline.


Images by @SciCommStudios


From → A Periodic Tale, Blog

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