Topic 1

• Atoms

  Tiny spheres that could not be divided
• Atoms


  • Consist of a small nucleus, which contains particles called protons and neutrons, around which electrons orbit
• Experiments have shown that atoms consist of a small nucleus, which contains particles called protons and neutrons, around which electrons orbit
• Chlorine


  The number 35.5 on the periodic table
• The number 35.5 on the periodic table for chlorine is not a mass number
• Deducing the relative atomic mass of boron

  Boron has two isotopes; 10B which makes up 20 % of naturally occurring boron and 11B which makes up 80 % of naturally occurring boron
• Deducing the relative atomic mass of gallium

  Gallium has two isotopes; 69Ga which makes up 60 % of naturally occurring gallium and 71Ga which makes up 40 % of naturally occurring gallium
• Deducing the percentage of each isotope in a sample of naturally occurring copper

  Copper has two isotopes; 63Cu and 65Cu. It has a relative atomic mass of 63.5
• Periodic Table


  A list of all the elements

  
• There are over 100 different elements. Ninety two of these are found in nature, the rest are man-made
• Periodic Table


  Why is it called the Periodic Table?

  
• Marking a blank Periodic Table

  Divide between metals and non-metals, Group 1 (the alkali metals), Group 7 (the halogens), Group 0 (the noble gases) and the Transition Metals
• Groups


  Vertical columns
• Periods


  Horizontal rows
• The elements are arranged in order of increasing atomic number
• Atoms of elements (except noble gases) take part in chemical reactions
• Atoms


  Form bonds with other elements during a chemical reaction to form compounds
• Chemical reaction


  Atoms either gain or lose electrons from their outer electron shell or share electrons from their outer shells in pairs
• Ions


  Electrically charged particles formed when atoms form bonds by gaining or losing electrons
• How positive ions are formed

  How negative ions are formed
• Drawing diagrams to show how the following ions are formed from their atoms

  1. Sodium ion

  2. Magnesium ion

  3. Aluminium ion

  4. Chloride ion

  5. Oxide ion
• When atoms form compounds they obtain the electronic structure of a noble gas
• Sodium atom


  2, 8, 1
• Chlorine atom

  2, 8, 7
• What happens in terms of electrons when sodium and chlorine react?

  The outer electron from the sodium atom is transferred to the outer shell of the chlorine atom to form a sodium ion (Na+) and a chloride ion (Cl-)
• Both the sodium ion (Na+) and the chloride ion (Cl-) have filled outer shells
• Ionic bond


  The attraction between the oppositely charged sodium ion (Na+) and chloride ion (Cl-)
• Compounds made from a metal and a non-metal are made from ions
• Metals


  Lose electrons to form positive ions (or cations)
• Non-metals


  Gain electrons to form negative ions (or anions)
• Molecules


  Formed when atoms form bonds by sharing electrons in pairs
• Covalent bond

  A shared pair of electrons between non-metal atoms
• John Dalton

  Arranged elements in order of their mass, measured in various chemical reactions that he had tried out
• John Newlands

  Noticed that there were many similar pairs of elements, where the atomic weights differed by a multiple of 8. He called this his 'Law of Octaves'
• Dmitri Mendeleev


  Collected a huge amount of data on the 63 known elements, made a card for each element, and arranged them in order of increasing atomic weight, and then into groups. This resulted in the Periodic Table, published in 1869
• Mendeleev left gaps for undiscovered elements and even predicted their properties
• Some of the elements Mendeleev predicted were later discovered, and their properties matched his predictions
• Mendeleev had to swap some elements around to get them in the right families, as they did not fit in order of atomic weight
• Modern Periodic Table


  Based on Mendeleev's periodic table, but the elements are now arranged in order of ATOMIC (PROTON) NUMBER instead of atomic weight

  
• Knowledge of atomic structure has proved that Mendeleev was right to swap potassium with argon and tellurium with iodine