C1.1 The Fundamental Ideas In Chemistry

Anexos:

• C1.2 Limestone And Building Materials
• C1.3 Metals And Their Uses
• C1.4 Crude Oil And Fuels
• C1.5 Other Useful Substances From Crude Oil
• C1.6 Plant Oils And Their Uses
• C1.7 Changes In The Earth And Its Atmosphere

1. C1.1.1 Atoms
   1. All substances are made of tiny particles called atoms.
      1. A substance made up of only one type of atom is called an element.
         1. Atoms of each element are represented by a chemical symbol; usually consisting of one or two different letters, but sometimes three letters are used.
            1. The first letter in a chemical symbol is a capital letter, and the others lowercase.
               1. Atoms have a small central nucleus, made up of protons and neutrons surrounded by energy levels containing electrons.
                  1. The first level can only hold two electrons and the second and third, eight electrons.
                     1. In an atom, the number of protons is the same as electrons. Atoms have no overall charge.
                        1. The relative electrical charges are as follows: protons +1, neutrons 0 and electrons -1.
                           1. The number of protons in an atom is the atomic number. The sum of the protons and neutrons is the mass number.
2. C1.1.2 The Periodic Table
   1. There are about 100 different elements; shown in the periodic table arranged by atomic number.
      1. Metals appear on the left with non-metals to the right.
         1. The horizontal rows are called periods and the vertical columns are called groups.
            1. Atoms in the same period have the same number of occupied energy levels and atoms in a group have the same number of electrons in the highest occupied energy level.
               1. Elements in group 0 have full energy levels and are inert. These elements are called the Noble Gases.
                  1. Elements in group 1 or 7 are the most reactive.
3. C1.1.3 Chemical Reactions
   1. When elements react, atoms lose, gain or share electrons to form ions or molecules.
      1. Compounds formed from metals and non-metals consist of ions.
         1. Metal atoms lose electrons to form positive ions and non-metals gain electrons to form negative ions. Oppositely charged ions are attracted, forming ionic bonds.
            1. Compounds formed from non-metals consist of molecules.
               1. Atoms share pairs of electrons in their highest energy level to gain full outer shells, forming covalent bonds.
                  1. Chemical reactions are represented by word equations or by symbol equations.
                     1. No atoms are lost or made during a reaction so the mass of the products equals the mass of the reactants.