KS3
Atoms, Elements and Compounds
Atoms are so small that we cannot even see a single atom under the world’s most powerful microscopes.
The atom
Everything is made up of atoms.
Atoms are the basic unit for all matter and are the building blocks for everything.
We refer to a single piece of matter as a particle. A particle can be referred to in many ways, for example, an atom, molecule or ion.
In the workplace
We can use this knowledge outside the world of science to help us in our careers. Here are some examples of where atoms can help us in our work
Interior Design
Understanding the chemical properties of different materials can help interior designers choose the most suitable materials for different spaces based on factors such as durability, texture, and colour.
Chemical Engineering
Knowing how atoms and molecules behave can help chemical engineers design better processes for manufacturing products.
Architecture
Having a good understanding of the properties of different materials at a molecular level can help architects design buildings that are more energy-efficient, durable, and sustainable.
Democritus
Around 400BC Greek philosopher Democritus discovered the atomos (atom). The word means uncuttable. Democritus believed that atoms were solid, incompressible, and indestructible spheres.
Aristotle
This theory was rejected by Aristotle (a very influential philosopher) as he believed it was illogical. At the time, Aristotle had everyone believe that everything was made of four elements: earth, fire, wind and water.
John Dalton
In 1803 John Dalton proved through experimentation that the atom was real. He came up with the ‘Billiard Ball’ model. This model is also referred to as the solid sphere model confirming Democritus’s theory.
Elements
An element consists of purely one type of atom. The atoms of one element are different to the atoms of a different element.
In some cases elements can also be pairs of atoms.
118 Elements
At present there are 118 different elements known.
Periodic table
We find the 118 elements on the Periodic table of elements.
Pure substance
An element is also referred to as a pure substance.
The Periodic table.
The most important thing to know is that each element has its own special name and a short code, like H for hydrogen, O for oxygen, and so on. These codes help scientists talk about elements easily.
The periodic table starts with hydrogen and helium at the top and goes all the way down to the heavy elements at the bottom. Elements on the left side are usually metals, and those on the right side are non-metals. In the middle, there are elements called metalloids that have properties of both metals and non-metals.
So, the periodic table helps scientists and everyone else understand and organize all the different elements in the world!
Group 1 - The Alkali Metals
These are the super friendly elements. They’re always ready to react with other elements and make new friends. Think of them as the “social butterflies” of the periodic table.
Group 2 - The Alkaline Earth Metals
These elements are also pretty friendly, but not as much as the alkali metals. They’re like the good friends you can count on.
The Transition Metals
These are the middle-of-the-road elements. They’re not too friendly or too unfriendly. They’re like the “normal” folks in the table.
Group 7 - The Halogens
These elements are like the troublemakers. They love to react with others and make things a bit chaotic. They’re kind of like the “mischievous” elements.
Group 0 -The Noble Gases
These are like the cool, calm, and collected elements. They don’t like to mix with others. They’re happy just being by themselves.
The Lanthanides and Actinides
These are like the special guests at a party. They don’t show up in the main part of the table. They have their own little area below because they’re unique and interesting.
Molecules
Molecules are made when two or more atoms chemically bond together.
When atoms of the same element join together, they form molecules.
Inert elements
Some elements are inert, which means they are unreactive.
They only exist as single atoms and so don’t react. On the periodic table, there is a group of these called the Noble gases (group 0).
We can also refer to these pairs of atoms as elements.
Chemical formula
Every molecule has its own chemical formula. Some examples are Oxygen O2, Hydrogen H2 and Nitrogen N2. These three examples are actually found naturally as molecules.
Compound
Molecules can also be made up of 2 or more different elements chemically bonded together. When this happens we call it a compound. Molecules cannot be compounds.
Larger molecules
Elements can form larger molecules such as O3, which is known as Ozone. Ozone protects us from harmful ultraviolet radiation from the Sun.
Compounds
Compounds are a type of molecule. A compound occurs when 2 or more different elements are chemically bound together.
Carbon dioxide
Carbon dioxide is a molecule, but it is also a compound. In carbon dioxide, one carbon atom bonds with two oxygen atoms. The formula for carbon dioxide is CO2.
Just like molecules, compounds have their own chemical formula. The formula for Ammonia is NH3, and for water is H2O.
Complex compounds
Some molecules (compounds) can be more complex for example glucose.
Glucose has the chemical formula C6H12O6.
Glucose is a simple sugar with other sugars being even more complex.
Glucose is required for Photosynthesis (in plants) and Cellular respiration.
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