Atomic Theory

Atomic Theory

1. Everything is made of elements but every element is made of very tiny particles called atoms

2. The atom is made of three smaller particles

   • > Electron - -Mass= Approx. O, -Charge= Negative, -Location= Energy Level/Outer Shell, 2,8,8.
   • > Proton - -Mass= 1 -Charge= Positive -Location= Nucleus
   • Neutron- -Mass= 1 -Charge= No charge/ Neutral -Location= Nucleus

3. The atomic number of an element tells you how many protons an atom of the element has

   • Atomic number = number of protons Number of protons = number of electrons Mass number= protons + neutrons Neutron Number = mass number - proton number

4. Nuclide Notation

   • • Protons = 11 Electrons = 11 Neutrons = 12

5. Alkali Metals- Most reactive metals, More reactive as they go down

   • Sodium is in group one and has one outer electron and so must lose one electron to be stable.

6. Halogens- most reactive non-metals

7. Noble Gases - most stable and non-reactive, have a full outer-electron shell(all other elements want to be like this)

8. Isotopes - atoms with the same atomic number but different mass numbers

   • Elements are made out of isotopes so the mass given s called the relative atomic mass (RAM), which is an average mass of all the isotopes of a single element
     • The RAM can be used to give an indication of the relative abundance of isotopes in a sample

9. Ions - Atoms are neutral because they have an equal number of positive protons and negative electrons. When there is an imbalance of electrons to protons an ion is formed

   • An ion is a charged particle and they are formed when an atom gains or loses electrons.
     • Metal atoms lose electrons to form positive ions and non-metal atoms gain electrons to form negative ions
     • The reason that atoms gain or lose electrons is because of the noble gases. All elements in the periodic table want to be like them in every way. This is why noble gases won't react as they don't need to be changed at all. This is called being stable.
       • Noble Gases have a stable electron arrangement (full outer shell)
     • positive ions are attracted to negative ions.
     • Positive metals become hydroxides (soluble). Negative metals become acids (except ammonium)

10. Across - row/period Up or Down - group/column (have similar properties)

    • Each group has a number starting from 1-8.
      • - Alkali Metals = 1 - Alkali Earth Metals = 2 - Transition Metals = don't have group number - the next three groups go from 3-6 - Halogens = 7 - Noble Gases = 8

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