Bonding in Elements

Do elements make relations? Yes they do; just as we make relations. Their relations are called “Bond”. Every element has a particular nature and it likes to make relation with a specific kind of element. Like us some elements are very friendly and make a number of friends, some are a little bit choosy and make a few selective friends and some like to be alone, these are royal type of elements.

Which factor guides their behaviour? Similar to our life where money factor decides most of the decisions, electron plays a major role in an element’s behaviour. To understand this you have to know how these electrons are distributed in an atom. In other words, you have to study financial condition of an element.

In the previous post you have learnt that every track allows a particular number of electrons. These tracks are called as “Orbits” in which electrons move around the nucleus. Orbit 1 allows only 2electrons, Orbit 2 allows 8, Orbit 3 also allows 18 and Orbit 4 allows 32 electrons.

Elements are not greedy like us. They just want to have 8 electrons in their outer most Orbit. If they have less than that, they like to borrow and if they have extra they love to give it. In their community 8 is the holy figure that every element tries harder to achieve. And those who already have this Octet (In Greek it means 8) are called Nobel elements. They like to live alone and rarely make any relation.

Let’s have a look on an element Sodium ¹¹Na, its symbol is ‘Na’ which is short form of its Latin name Natrium. It has 11 electrons. When you distribute them in orbits, you find 2 electrons in 1^storbit, 8 electrons in 2^nd orbit, and remaining 1 electron in 3^rdorbit. If it loses 1 electron it will have 8 electrons in 2^nd orbit.

When you study electronic distribution of element chlorine ¹⁷Cl, you find 2 electrons in 1^st orbit, 8 electrons in 2^nd orbit and 7 electrons in 3^rd orbit. There is one less than eight electrons in outer most orbit. Cl is looking for someone who can give him one electron.

Cl wants 1electron and Na wants to lose 1 electron. So they come together and make a bond. Thus they both achieve octet and stay together as NaCl (sodium chloride). You can find it in your kitchen. Without it nothing can taste better. It’s your table salt.

You know atoms are neutral because there electrons and protons are present in equal number. When atom loses or borrows electrons in order to achieve octet state, it disturbs the balance of charge. It means either negatively charged electrons or positively charged protons become in excess and the majority decides the charge of the atom. Charged atom is called “ion”. Charge of an ion is written in the right superscript.

When sodium donates an electron, it becomes positively charged because now protons are in majority. It is now called sodium ion Na⁺. Similarly Chlorine becomes negatively charged as it borrowed an electron. It is called as chloride ion Cl^- .

Now these oppositely charged ions attract each other and make a bond. This bond is called “ionic bond”.​

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How to Write Electronic Configuration

Electrons are much disciplined runners. As you know electrons move around the nucleus in certain orbits. Like any racing game, electrons also have to follow some rules. These rules decide the orbit of an electron, space ship it will travel on, and also the particular seat for it. When you see an atom you will find it much organised, even you can guess the arrangement of electrons in it. But you must know the rules.

Rule 1 is about orbit.

It is named as “The Aufbau Principle” (aufbau is German for “building up”). Orbit nearer to the nucleus, which has lower energy, is to be filled first. It means orbit 1will be filled first then 2 then 3 and so on.

If you take an example of element Lithium (³Li), it has 3 electrons. First they have to fill orbit 1 and then move on to the next one. Orbit 1 allows 2 electrons so 2 of 3 electrons will there and remaining 1 electron will go to the orbit 2.

Rule 2 is about space ship.

Space ship is called “Sub-Shell”. You know every orbit has different sub-shells. Orbit 1 has “s” sub-shell, orbit 2 has “s” and “p” sub-shells, orbit 3 has “s”, “p” and “d” sub-shells and orbit 4 has “s”, “p”, “d” and “f” sub-shells.

Every sub-shell has different energy and its energy also depends on the energy of the orbit it belongs to. Orbital “s” is the lowest energy sub-shell and “f” is the highest energy sub-shell.

Energy order of the sub-shells is as follows: s < p < d < f

When you compare the energy of sub-shells belonging to different orbits you will find

1s < 2s < 2p < 3s < 3p < 3d

Let’s take an example of Boron (⁵B), it has 5 electrons. First 2 electrons will go in 1s, next 2 electrons will go in 2s and remaining 1 will go in 2p. Now you are able to distribute electrons in orbits and sub-shell. How do you write your finding in a precise manner? 

·               ​First write orbit number before sub-shell,

·               Number of electrons is to be written in the right superscript.

This way of presentation of electrons distribution is called “Electronic Configuration”. Now try to write electronic configuration of Boron​.⁵ B = 1s², 2s², 2p¹

Rule 3 is about assigning the seats in a spaceship.

You know every spaceship or sub-shell has different number of compartments. These compartments are named “Orbitals”. Orbitals of the same sub-shell have equal energy and these are called “Degenerate Orbitals”. Every orbital can accommodate maximum 2electrons.

This rule is called “Hund’s Rule” (given by the scientist Friedrich Hermann Hund). It states that when there are degenerate orbitals electron will occupy an empty orbital before it will pair up with another electron.

Let’s take an example of Oxygen (⁸O), it has 8 electrons. And its electronic configuration will be ⁸O = 1s², 2s², 2p⁴

​​

If you remember I have told you that electrons are like spin top. Every electron revolves clockwise or anticlockwise in its axis while it travels in the orbit. When they share single orbital one of the electron revolves clockwise and the other one anticlockwise. Clockwise rotation is represented by half up side arrow and anticlockwise rotation by half down side arrow. Let’s place electrons of oxygen in their corresponding orbitals.

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Elements in human body

Out of 118 elements 29 are found in our body. 99% mass of the human body is made up of just six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. But there are a number of elements found in our body which play vital role.

No.	Name of Element	Where it is Found in our body
1.	Oxygen (65%)	Predominantly found in the form of water in our body
2.	Carbon (18%)	Every cell is made up of it
3.	Hydrogen (10%)	Predominantly found in the form of water in our body
4.	Nitrogen (3%)	Found in Muscles and DNA
5.	Calcium (1.5%)	Found in Bones
6.	Phosphorus (1.0%)	Found in Bones and in energy generator cells
7.	Potassium (0.35%)	Vital for electrical signalling in nerves
8.	Sulphur (0.25%)	Found in two amino acids that are important for giving proteins their shape
9.	Sodium (0.15%)	Vital for electrical signalling in nerves. It also regulates the amount of water in the body.
10.	Magnesium (0.05%)	Found in Skeleton and muscles. It is also necessary in more than 300 essential metabolic reactions.
11.	Iron (0.70%)	Found in Blood and gives red colour to it.
12.	Chlorine (0.15%)	It is important for maintaining normal balance of fluids
13.	Copper (0.0001%)	Without enough copper, iron won't work properly in the body
14.	Iodine (0.000016%)	It is required for making of thyroid hormones which is responsible for brain and body growth
15.	Fluorine (0.0037%)	Found in teeth and bones
16.	Selenium (0.000019%)	It is essential for certain enzymes, including several anti-oxidants.
17.	Zinc (0.0032%)	Several proteins contain structures called "zinc fingers" which help to regulate genes. Zinc deficiency has been known to lead to dwarfism.
18.	Chromium  (0.0000024%)	It helps regulate sugar levels by interacting with insulin
19.	Manganese  (0.000017%),	It is essential for certain enzymes in particular the ones that protect mitochondria (the power house of cell) from dangerous oxidants.
20.	Molybdenum  (0.000013%)	It is important for transforming sulphur into a usable form.
21.	Cobalt, Lithium, Strontium, Aluminium, Silicon, Lead, Vanadium, Arsenic, Bromine (trace amounts)	Roles not known

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Periodic Table: Address Book for Atoms

Click on to view Periodic Table

Atoms are like us. Even though we all are made up of flesh and bone, everyone is different and unique. Similarly, all atoms are made up of subatomic particles like proton, electron and neutron. These subatomic particles give identity to an atom and make is different to another. Every atom has different set of subatomic particles.

Like us atoms also have names and address. The atom which has 1electron and 1 proton is named as Hydrogen. And an atom which has 2electrons and 2 protons is named as Helium. As one kind of animals make a species, one type of atoms combine to make an element. There are total 118 different elements. These elements are present everywhere in the universe. You can find their details in their address book. This address book is called “Periodic Table”. Elements are arranged there according to their Identity number.

Elements have Identity number. As we have now in the form of “Adhar card” in India, and Social Security number in United States. Element is defined by their atoms, that’s why this identity number is given on the credentials of the atom. For an element, identity number is a set of atomic number and atomic mass. Atomic number is the number of electrons present in an atom and atomic mass is the mass of an atom.

In the periodic table elements are arranged in an increasing order of their atomic number. It is divided into columns and rows. It has 18 columns and 7 rows. Elements are arranged in such a way that similar type of elements gets the same column. Like in cities cantonment area is mostly populated by defence persons.

As there is a particular way of writing our full name like we write our name first than surname. An element’s name is written with its identity number. It is much like a signature because it contains symbol instead of full name. Let’s see. Symbol for Oxygen is ‘O’ its atomic number is 8 and atomic mass is 16.

Atomic number is written in left super script and atomic mass in left subscript to the symbol of the element. 

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What is an Atom?

It is the story of an atom. Atom is just like us. As you know, in this universe everything has one counterpart like day-night, good-bad, hot-cold, plus-minus and so on. Atom also has positive and negative parts. Its positive part is called proton and its counter companion is electron which is negative. They are always present in equal number to maintain the neutrality of an atom. As you can understand they cannot stay together. Both have their unique character. Electrons are quite restless and full of energy unlike protons. So protons choose to go in the core/nucleus of an atom and rest there. While electrons prefer to continually revolve around the nucleus. Yes, just like planets in our solar system revolve around the Sun. You know every planet has its own track in which it moves around the Sun. Electrons also have their tracks and each track has its particular energy level. Just imagine electrons are moving in a circular racing track with the nucleus at its centre. Inner tracks are closer to the nucleus and smaller than others. They are occupied by less energy electrons. As the distance between nucleus and tracks increases, energy level of tracks increases and so does the energy of electrons belonging to them.

How do electrons move around? Do they run or jump or walk? An electron's motion is like our Earth. Just like the Earth, it revolves around its axis and simultaneously moves in its track. You can also compare it with your childhood toy “spin top”. Every electron revolves clockwise or anticlockwise in its axis while it travels in the track.

How many electrons can run in a particular track? Every track allows a particular number of electrons to run. Track 1 which is closest to the nucleus allows only 2electrons. Track 2 allows 8 electrons, track 3 also allows 18 and track 4 allows 32.

Do electrons have some vehicle or anything like that? Yes they have. As you know, everyone can afford a different car according to their status. You can imagine that Electrons travel in different models of spaceships. These spaceships are provided to them according to their energy level or in other words according to the  track in which they are moving. Every spaceship has a different occupancy and shape. Spaceship for the electrons moving in track 1 have “s” model of spaceship. This model is spherical in shape and has only one compartment with 2 seats. Spaceship for the electrons moving in track 2 have two models of spaceship “s” and “p” model. Model “p” is dumbbell  shaped and has three compartments, each of which has 2 seats. Spaceship for the electrons moving in track 3 have three models of spaceship “s”, “p” and “d” model. Model “d” is double-dumbbell shaped and has five compartments, each of which has 2 seats. Spaceship for the electrons moving in track 4 have four models of spaceship “s”, “p”, “d” and “f” model. Model “f” is the most superior one and it has a very complex shape and has seven compartments, each of which has 2 seats.

 

Now you can imagine protons are staying inside the nucleus and electrons are roaming around it in the tracks. Electron looks like your “spinning top” which is travelling in its spaceship.

You may wonder how all protons gently stay in the nucleus. They all have positive charge they must repel each other like same magnetic poles do. Yes they repel each other, but for the harmony the peace maker neutrons are present inside the nucleus. They are neutral in charge so they keep protons at a safe distance.

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