Part 1 THE STRUCTURE OF THE ATOM

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Part 1THE STRUCTURE OF THE ATOM

• Objectives
• Know the names and arrangement of the particles
  in an atom
• To be able to describe the differences in mass of
  the particles
• To know the charges on protons, electrons and
  neutrons.

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The Atom

• Everything that exists is made from particles.
• These particles are called ATOMS
• Atoms are made up from three smaller particles
• These are called Protons, Electrons and Neutrons

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How the particles are arranged

• In the centre of the atom we find the nucleus.
  This contains the protons and the neutrons.
• Around the outside we find the electrons.

Electrons orbit the nucleus
Nucleus containing protons (red) and neutrons
(green)
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What are the particles are like?

• The protons have a mass of 1 and have a positive
  () charge.
• The electrons are very small particles and have
  almost no mass. They have a negative charge (-)
• The neutrons have a mass of 1 and no charge.
• Click here to complete exercise
• Save a copy of the completed exercise in your
  area and then print it

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The Periodic table

• Elements are made from atoms
• Elements are found on the Periodic table.
• Each element has only one type of atom.
• Elements are arranged in columns called groups
  and rows called periods.

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What does it all mean?

• Each element has a mass number (the bigger one)
• Each element has a symbol (short way of writing
  it)
• Each element has a name
• Each element has an atomic number (the smaller
  one)

• 23
• Na
• SODIUM
• 11

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CLICK HERE TO PRINT AND COMPLETE EXERCISE
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The atomic number and the mass number

• The atomic number tells us how many protons there
  are in the atom.
• There are always the same number of protons and
  electrons in an atom.
• The mass number tells us how many protons and
  neutrons there are added together

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How many?

• 23
• Na
• SODIUM
• 11

• Atomic number is 11
• This means there are 11 protons in an atom of
  sodium
• Mass number is 23
• This means there are 23 protons and neutrons
  added together.
• We know there are 11 protons so there must be 23
  11 neutrons which is 12
• CLICK HERE TO COMPLETE EXERCISE

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