Atoms

Atoms

1. The particles that make up all matter

2. Scanning Tunnelling Microscope (STM)

3. Protons, neutrons and electrons are the subatomic particles that make up atoms.

   • Nucleus: A tight, dense bundle of protons and neutrons found at the centre of an atom. Almost all of the atoms mass is in its nucleus.
   • Shell: The space surrounding the nucleus where the electrons spin around
   • Protons: Have a positive charge and a mass of 1.
   • Neutrons: Have no charge (neutral) and a mass of 1.
   • Electrons: Have a negative charge and a mass close to 0.

4. Atoms are electrically neutral because the number of protons (+) = the number of neutrons (-)

5. Elements

   • The building blocks from which all substances are made.
   • An ELEMENT is a pure substance made of only one type of atom.
   • The number of protons in the nucleus determines the element to which the atom belongs.
   • Currently 118 elements known, 26 of these not found naturally on Earth
   • A COMPOUND is made of atoms of different elements.
   • Atomic number: The number of protons in the nucleus of an atom. Elements are listed on the periodic table in order of increasing atomic number.
   • Mass Number: The total number of particles in the nucleus of an atom.
   • ISOTOPES are atoms that belong to the same element, with the same number of protons and same atomic number. They have different mass numbers because they have different numbers of neutrons.
   • ISOTOPES are atoms that belong to the same element with the same number of protons and same atomic number. They have different mass numbers bec

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