What Are Atoms?
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What Are Atoms?

What are atoms? To understand chemistry one has to know the atom. But it is not enough to know something that is not visible. Because the atom is so tiny, much of the information about it is the realm of abstractions and theories. Know more by reading more...

According to a famous scientist to understand chemistry one has to know the atom.  But it is not easy to know something that is not visible.  Because the atom is so tiny, much of the information about it is in the realm of abstractions and theories.

What are atoms?

"What are atoms?", you may ask.  Why study atom?  Why not let the chemist spend their lifetime on the study of it's behavior and structure?  You may feel that knowing the atom is not necessary.  Perhaps you would rather be concerned with the more important business of daily living.

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Have you ever wondered what a flower is made of?  Or everything else for that matter?  Everything around you, such as the rice and fish on your table, the maong pants and t-shirt you wear to school, and windows and roofs of your house, is made up of atoms.  Even you are a complicated collection of billions and billions of atoms arranged systematically and orderly.  Are those not good enough reasons to know this subatomic particle? 

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Let us examine a piece of rock under a magnifying lens.  Limestone which is very common in our country would  make a good specimen.  If you crush the rock into tiny particles, you will notice that these tiny units are one kind of material.  If you examine the larger specimens of minerals, you will discover that they have regular geometric shapes with smooth flat surfaces.  Then scientists try to find out what it is made of.  The smaller units of a mineral are know as elements.  Limestone is composed of the mineral calcite, and in turn, is made up of the elements calcium, carbon and oxygen. 

If you take an element Gold, for instance and reduce it into the smallest particle of that substance, that still has the properties of Gold, then you have produced what is called an atom of the element.

According to researchers, the Greeks were the first to introduce the idea of a fundamental building unit of matter.   The word atom is an ancient Greek word for "uncut" because it was thought until recently that the atom could not be divided by chemical process, but they can be taken apart by mechanical means.  If a tiny particle which is hurled with lightning speed hits an atom, it will break the atom up into simpler parts.

Structure of atom

An atom is pictured as a sphere with the nucleus at it's center.  While all atoms consist of the same kind of particles, atoms of different elements differ from each other.  This is so because each element is a special combination of protons, neutrons, and electrons.  The number of protons in it's nucleus distinguishes an element from another.

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Subatomic particle:

  • Electrons
  • Protons
  • Neutrons

Protons and neutrons are found at the central portion of the atom called the nucleus.  Around the nucleus speed the electrons.  The electrons spin in such a tremendous speed that they seem to fill up the space about the nucleus in the same way that the blades of an electric fan appear to fill up the spaces between them when they are turning fast.

An atom is electrically neutral because there are the same number of electrons outside the nucleus as there are protons in the nucleus.  In forming compounds, atoms sometimes loss or gain electrons to form charged particles called ions.  An atom that has lost electrons becomes positively charged (cation).  While an atom that has gained electrons becomes negatively charge (anion)

How do atoms combine

The electrons of an atom follow a definite paths of travel around the nucleus of atoms called the energy-levels.  It is also called orbits.  These orbits are arranged systematically at different distances from the nucleus.  The distances are referred to as energy-level shell.  Electrons revolving at the same average distance from the nucleus occupy the same shell, beginning with the first shell K, chemists refer to them as shells K, L, M, N, O and Q.

Electron arrangement is called electron configuration.  Knowing how to predict electron configuration  is important because the arrangement of electrons control an atom's chemical properties.

The number of electrons in their outermost energy levels is the most important structural feature of atom in determining chemical behavior,  In compound formation, atoms of certain elements tend to gain electrons and others tend to lose electrons.   The electrons that are involved in a chemical reaction is the outer most electrons or are called valence electrons.

Atoms of elements  with eight electrons in their outermost shell do not combine readily with other elements.  Elements that have fewer than eight electrons in their outermost shell readily give away or attract other electrons to achieve eight.  Atoms can form stable electron configurations by losing elections, gaining electrons, and sharing electrons.

For a stable electron configuration each atom must fill it's outer energy level, it means eight electrons in the last shell.  Atoms that have 1, 2 or 3 in their outer levels will tend to lose them.  Atoms that have 5, 6 or 7 will tend to gain electrons.  While atoms have 4 electrons in the outer most energy level will tend neither to totally lose or totally gain electrons during the reactions.


1) Fill up the table and sketch the electron configuration of each element:       

 ELEMENT ATOMIC NUMBER Number of Electrons in the outermost shell
1) Bh    
2) Fm    
3) Mt    
4) No    
5) Tb    
6) Cn    
7) Uut    
8) Uup    
9) Uus    
10) Hs    

2)  What is the charged of the nucleus and why?

3)  What is the reason why an atom is electrically neutral?

4)  Why study atoms?  Give three reasons in your own words.

5)  In order for elements to stabilize; they need to completely fill their outermost shells with eight electrons.  Explain two (2) ways to attain this stable situation?

Resource:   Science Encyclopedia

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Comments (4)
Ranked #10 in Science

Very useful reference to students.

Ranked #4 in Science

Thanks for the positive comment Patrick...

Very thorough discussion of atoms. It has been 30 years since I studied atoms in Chemistry class, and I clearly have forgotten a large part of this!

Ranked #4 in Science

Thanks for dropping by Sharla...