Atomic Structure:
Terms to Note:
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To view atoms an electron microscope must be used
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An atom is the smallest particle of an element while still retaining the properties of that element.
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The tiny particles found inside the atom are called sub-atomic particles
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The three sun-atomic particles are neutrons, protons and electrons
The Sub-atomic Particles:
An electron microscope
Paricle: Where is it situated: Relative Mass: Relative Charge:
-Proton -Nucleus -1 unit - +1
-Neuton -Nucleus - 1 unit - 0
-Electron -Electron - 1/1840 unit - -1
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As you can see from above the mass of each particle is measured in "units". These units are atomic mas units or A.M.U.
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The electron is the only sub-atomic particle not found in the nucleus. It is instead found in the electron cloud outside the nucleus
Important Points on atoms:
This Diagram shows the location of the sub-atomic particles.
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Electrons have a negative charge, neutrons have a neutral charge and protons have a postitive charge
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Every element has an atomic number and a mass number and these can be used to help us discover the number of neutrons, protons and eletrons are present
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Take for example aluminium. It has a mass number of 27 and an atomic number of 13 which is displayed clearly on the periodic table
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Knowing that the atomic number of an element is equal to the number of protons and electrons. We now know that there are 13 protons and electrons
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Then to discover the number of neutrons in an atom we simply subtract the mass number from the atomic number. If we take aluminium we will suntract 27 from 13 meaning there are 14 neutrons
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If in an exam you need to find out the mass number of an element simply subtract the number of neutrons from the atomic number (number of protons).
Left: The nuclear formula of an equation allows you to find out the number of sub-atomic particles present
Right: A diagram with a summary of all the equations used to find the sub-atomic particles
