C3 Atoms, Elements and Compounds

C3 Atoms, Elements and Compounds

1. Physical and Chemical changes

2. 3.2 Elements, compounds and mixtures

   • Atom: Smallest particle of matter
   • Molecule: A small particle made from more than one atom bonded together
   • Element: A substance made out of only one type of atom
   • Compound: A substance made out of two or more different elements chemically bonded together
   • Mixture: A substance made out of two e more elements or compounds that are not chemically bonded together

3. 3.3 Atomic structure and the periodic table

4. 3.4 Ions and Ionic bonds

   • Electron transfer between metals and non-metals to gain full outer shells. The oppositely charged ions attract eachother
     • Sodium Chloride forms a giant ionic lattice
       • lattice- a repeating pattern of negative an positive ions
         • each ion is surrounded by 6 oppositely charged ones creating an electrostatic charge--- strong ionic bonds require a lot of energy to break them so they have a high melting point
         • When molten they can conduct electricity as electrons are free to carry a charge
     • metals loose electrons
     • Like covalent bonding ionic bonding can occur with more than than two ions e.g MgCl2

5. 3.5 molecules and covalent bonds

   • Covalent bonds are between two non-metals
   • Covalent molecules have strong covalent bonds and weak intermolecular bonds that break on heating
     • - Low melting point
     • Volatile- they evaporate easily
     • Do not conduct electricity
     • insoluble in water
       • ionic are soluble in water
     • Giant covalent strucutres
       • diamond is made up of carbon atoms- each carbon atom is bonded with 4 others making it very hard
         • used in industrial tools
       • Graphite is made of carbon which is arranged in hexagonal sheets. This also them to slide over eachother
         • used as a lubricant

6. Proton number (atomic number) is the number of protons

   • This is equal to the number of people

7. Nucleon number is the sum of neutrons and protons

8. Neutron number= mass number- proton number

9. Isotopes are the atoms of an element with different numbers of neutrons. They have the same proton number, but different mass numbers

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