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My Attempt to Explain Density in Layman’s Terms.

When we pick up a rock it seems heavy for its size, how heavy an object feels has to do with how much and what kind of stuff it contains, which is called its density.

By A B ForbesPublished 9 months ago 7 min read
My Attempt to Explain Density in Layman’s Terms.
Photo by Daniel Leone on Unsplash

Atoms are the smallest particles of chemical elements that exist and are the basic building blocks of everything we see, touch and smell.

British spelling.

Apart from a hydrogen atom which has only one proton at its centre and one spinning electron, all other individual atoms contain various amounts of protons, neutrons, and electrons.

A hydrogen atom is the simplest and lightest of all atoms.

Chemical elements like oxygen, iron, and gold to name a few are all made of the same type of atoms that have the same number of protons in their nucleus, that is their atomic number, therefore all the atoms in a named element will have the same atomic number.

As we move up the periodic table the atoms get heavier due to having more protons and neutrons in their nucleus.

Most of us will have held a piece of lead at some time, yes it feels heavy, lead is a chemical element with the symbol Pb and atomic number 82, it is the 82 protons and 126 neutrons in its nucleus that give it its weight, its nucleus is surrounded by 82 electrons.

Electrons have also a weight but it is minuscule.

The mass of an atom is the total number of protons and neutrons combined. To give you an idea of the size of an atom and how small they really are, take a human being of say 70 kilograms in weight, the total number of atoms making up that person’s body is estimated to be 7 octillion which is a staggering 7,000,000,000,000,000,000,000,000,000 atoms!

The most common atoms by mass that make up 99% of the human body are oxygen, carbon, and hydrogen.

When we die, all the elements we were made of will dissipate over time and eventually become part of other objects or living things in the future.

A molecule is an electrically neutral group of two or more atoms held together by chemical bonds, every combination of atoms is a molecule, and they can be simple or complex. To give an example, a water molecule is composed of one oxygen atom and two hydrogen atoms, and a carbon dioxide molecule is composed of one carbon atom and two oxygen atoms.

Matter is the term used for any kind of material that takes up space. It is all around us. Matter is the air you breathe, the shoes you are wearing, the water in your glass, and everything around us, it is what we are.

Anything that has mass is matter and it comes in five known states, three commonly known as solid, liquid, and gas, the other two being plasma and bose-einstein condensates. The difference in the structure of each state is described as the densities of the particles.

Mass is a combination of the total number of atoms, the density of the atoms, and the type of atoms in an object. Every object in the Universe is made up of matter and the bigger an object is the more mass it has. Mass is measured in kilograms or (kg).

Objects that have a big mass are harder to move or harder to stop than objects with less mass, the mass of an object can only change if you add or take away matter. You can place an object in different parts of the Universe but it will always have the same mass. Weight is not the same as mass as you will see in the next paragraph.

Weight is the result of the force of gravity acting upon an object, which can change if the force of gravity changes. I weigh 80 kilograms on Earth but if I took the next flight to the Moon and weighed myself there I would register at just over 13 kg, the reason being the Moon’s gravity is much less than that of the Earth, and therefore I am being pulled down on the scales with less force than I would be on Earth.

On Mars, my weight would be just over 30 kg. If it was possible to stand on the Sun (which I am not recommending)! my weight would be over 2,165 kilograms, as the Sun’s gravity is almost 28 times as strong as that of the Earth, and if I was floating in outer space with no gravitational attraction from any objects my weight would be zero.

Even the air we breathe has weight, the mass in one cubic meter of air weighs approximately 1.2 kg, on a windy day, you can feel the weight of the air acting on your face and your body.

If you can imagine a column of air one-centimetre square sitting at sea level and going all the way up to space, then the weight of that air column would be classed as atmospheric pressure.

On Earth that weight exerts a pressure of around 1 bar per square centimetre, however, you don’t notice this weight because we are accustomed to it. If you were to climb to the top of Mount Everest, then the air pressure there would be about one-third of what it is at sea level.

Density is a measure of mass per unit of volume, an object made from a comparatively dense material such as gold will have less volume than an object which is not so dense, such as aluminium or in the USA, “aluminum”.

If you were to take 1 kg of gold and shape it into a ball, then do the same with 1 kg of aluminium, then the gold ball will be smaller in diameter than the aluminium ball of the same weight. I know that is a very simplistic explanation!

Objects with the most extreme densities in the Universe are neutron stars and black holes,

I hope that these next few lines will provide a simple understanding of the concept of density.

We are all familiar with a scrap car/automobile being crushed into a small block, pressure is causing the car parts to move closer together, thus eliminating some of the space between them.

Now an atom that is mostly “empty space” can also be compressed, but what is needed is a much greater force, that force being extreme gravity.

Now you will have to use your imagination. As I said a hydrogen atom is the simplest and lightest of all atoms, it contains just one proton in its nucleus, (the centre) and one spinning electron.

This paragraph should give you an idea of how much empty space there is in atoms. Scale a hydrogen atom up so that it is 4 kilometres in diameter, at that scale the proton in its centre would be the size of a golf ball.

The distance electrons are from the nucleus of an atom gives it its size or edge and determines how close atoms can be to each other.

Under extreme gravity protons and electrons can combine to form neutrons, now the area where the electrons were spinning around the nucleus has been eliminated, and the mass is in a much smaller area.

Neutron star material taking up an area the size of a sugar cube would weigh an incredible one hundred million tons here on Earth.

Imagine a star with roughly 1.5 times the mass of the Sun and squeeze it down to an object 15 kilometres in diameter, that small object has become a neutron star. Now you can see how very dense neutron stars are, they are mostly made of neutrons, hence their name.

End of the main article.


We can only imagine what our early ancestors were thinking as they gazed up at the night sky, were they curious as to what the heavens had to hide?

Image by Rene Tittmann from Pixabay

Now it is very different as we have developed sophisticated telescopes and other specialised scientific instruments that are helping to reveal some of the secrets the Universe holds.

Simple life forms were living on our planet almost 4 billion years ago, since that time billions of animal species have existed, and millions of species are still alive today.

For me, the only plausible reason for the vast number of animal and plant species we see all over the world is the evolutionary process. But of course, our lives are too short to witness the tiny changes taking place in populations.

The evolutionary path for humans has been extremely long but at last, we have arrived. Our highly developed brain has given us intelligence and curiosity, now we can try and make sense of what we see on Earth and out there in that gargantuan area, we call the Universe.


You might enjoy reading some of my easy-to-understand articles regarding the Universe and Life.

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About the Creator

A B Forbes

I hope you find some of my articles interesting.

Our highly developed brain has given us intelligence and curiosity, now with the help of sophisticated scientific instruments, we can try and make sense of the Universe and our existence.

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  • A B Forbes (Author)9 months ago

    Author. My articles are written for people with an average understanding of the universe and life. We are not all experts. I hope you gain some knowledge if you decide to read them. Regards.

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