Atoms and elements

Atoms and elements

1. Nucleus=Protons and neutrons

   • Electrons move around the nucleus
   • Atoms have no overall charge
     • No. of protons= No. of electrons

2. One type of atom

   • 1 proton=Hydrogen
   • 2 protons=Helium

3. Symbols

   • Na= Sodium
     • Fe= Iron
       • Pb= Lead

4. Periodic Table

   • rows-ACROSS(SIMILAR PROPERTIES)
   • Groups-DOWNWARDS(SAME AMOUNT OF ELECTRONS IN OUTER SHELL)
     • Group 1 - Reacts with water (forms alkaline solution + hydrogen gas)
       • Group 0 = NOBLE GASES (8 electrons in the outer shell)
         • UNREACTIVE
         • EXCEPT HELIUM IT ONLY HAS 2 ELECTRONS!
   • Mass number= top number of the symbol
     • Atomic number= bottom number of symbol
       • Protons and electrons
     • protons and neutrons

5. COVALENT BONDING

   • Between 2 non-metals
   • Molecules sharing!

6. IONIC BONDING

   • Between a non-metal and metal
     • Giving or taking
     • Ions

7. MASS OF PRODUCTS= MASS OF REACTANTS