C4

C4

1. Atomic structure

   • Electrons: negative, 0
   • Neutrons: neutral, mass = 1
   • Protons: positive, mass = 1

2. Bonding

   • Compounds are substances in which atoms of two, or more, elements are not just mixed together but chemically combined. This is known as Bonding.
   • Chemical reactions between elements involve either the giving and taking, or sharing, of electrons in the highest occupied energy levels of atoms.
   • https://youtu.be/R0g-H1dcfnY
   • Covalent Bonds
     • When non-metals react together both atoms need to gain electrons to obtain a full shell of electrons. The atoms are held together by shared pairs of electrons. The shared pair of electrons is a covalent bond.
     • Methane is formed from one carbon atom and four hydrogen atoms. Each carbon has four outer electrons and each hydrogen atom has 1 outer electron.
       • Sharing gives both types of atom full outer shells.
   • Ionic bonding
     • An ionic bond is formed when electrons are lost and gained by two or more atoms.
       • When atoms gain electrons they become negative ions
       • When atoms lose electrons they become positive ions
     • formed between metals and non - metals.
   • Metallic Bonding
     • Metallic bonding = positive metal ions are held together by electron clouds.
     • Metals conduct electricity because... The electrons are free to move through the structure
     • The melting points decrease as you go down the group. The atoms get larger as you go down the group (because they have more shells of electrons).
     • 1 electron in the outside shell
     • As you go down the group, they get even softer