C4: Chemical Patterns

1. 1. Dobereiner's Triad's
   1. Dobereiner put the elements into groups of three based on their chemical properties.
   2. The middle element had a RAM which was average of the other two.
2. 2. Newland's Octaves
   1. Newlands noticed that when you put element in order of their relative atomic mass, every eight element had similar properties.
   2. But the pattern broke down on the transition metals.
   3. Newland's work was ignored by the chemical society because he didn't leave gaps for undiscovered elements, nor did his groups have similar properties.
3. 3. Mendleev
   1. Mendleev left gaps and predicted new elements, he noticed the gaps needed to be made in order for each vertical group to have similar properties.
   2. His ideas were confirmed when his predictions were proved to be correct.

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1. puts elements with similar properties together, laid out in increasing proton number.
   1. Arranging the elements like this means that there are repeating patterns in the properties of elements.
      1. If you know the properties of one element in the group, you can predict the properties of other elements.
      2. Making predictions about reactivity can be done because the elements are arranged in this way.
2. Rows= Periods
   1. Colums= groups
3. Relative atomic mass= sum of protons and neutrons
4. 288

1. Some metals, like iron, copper and tin form ions with different charges. The number of brackets after the name tells you the positive charge e.g. iron (II) has a charge of +2, so the ionic formula is Fe2+.
2. The charges on an ionic compound add up to 0.
   1. To balance ionic formulas one must put numbers in front of the numbers, like a regular equation..

1. Ions are made when atoms gain or loose electrons.
   1. Group 1 become positive ions when they complete their outer shell.
   2. Group 7 become negative ions when they complete their outer shell.
2. Transferring electrons
   1. Oppositly charged ions are strongly attracted to each other. They stick to another oppositely charged ion and form an ionic bond.
      1. Sodium and Chlorine
         1. Chlorine (7) picks up sodium's spare electron and becomes a negative ion, as sodium (1) looses this electron it becomes positive. As the two ions are now strongly attracted to each other, they stick and form an ionic bond.
         2. Solid ionic compounds (like sodium chloride) are made up of giant lattice of ions. Each lattice forms a single crystal.
            1. The fact that the molten compounds of metals and non-metals can conduct electricity is proof that they're made up of ions.

1. Oxidising
   1. Provides oxygen which allows other materials to burn more fiercely.
2. Toxic
   1. Can cause death either by swallowing, breathing in, or absorption through the skin.
3. Explosive
4. Highly Flammable
5. Corrosive
   1. Attacks and destroys living tissue.

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