4.1 Atomic Structure and Periodic Table

4.1 Atomic Structure and Periodic Table

1. Everything is made of atoms, small particles with a nucleus and electrons.

   • Elements are single atoms that have the same number of protons and compounds are multiple elements chemically bonded together.
     • Elements and compounds are represented by symbols e.g. O and CO2

2. Word equations are ways of writing out chemical reactions e.g. hydrogen+oxygeon->water

3. A mixture is a substance comprising elements and compounds that are not chemically bonded together.

   • To separate mixtures use distillation or evaporation.

4. Particle Charges

   • Proton +1
   • Electron -1
     • Fill shells in the order 2, 8, 8
   • Neutron 0

5. Isotopes

   • Atoms with the same number of protons but different numbers of neutrons.
   • Relative atomic mass is the average mass of all isotopes of a given element.

6. The periodic table

   • Elements arranged according to atomic number.
   • Atoms in the same group have similar properties due to having the same number of electrons on the outer shell.
   • First to correctly classify elements was Mendeleev, who rearranged according to atomic number and left gaps for undiscovered elements.
   • Group 0 have no reactivity due to a full outer shell.
   • Group 1 are highly reactive due to 1 atom in outer shell.
     • Group 7 are diatomic and get less reactive down the group.
   • Transition metals are shiny, malleable, highly conductive, and have high melting and boiling points.

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