1.3 The Periodic Table

• Arrangement of elements in the periodic table
• Relating position to electron arrangement
• Formation of ions
• Deriving formulae of compounds
• Writing and balancing chemical equations

• relate the position of an element in the periodic table to its electron arrangement
• illustrate ion formation of elements
• derive the formulae of compounds
• write balanced equations for chemical reactions
• appreciate the role of electron arrangement in the development of the periodic table

“Why are the elements arranged in that particular order?”

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1. Position and electron arrangement
   40 min · 2 practice tasks · quiz
   Why the table is shaped as it is, and reading an element from its address.
2. Ions, formulae and equations
   40 min · 2 practice tasks · quiz
   Atoms gaining and losing electrons, and writing what happens when they react.
3. How the periodic table was invented
   40 min · 1 practice tasks · quiz
   Dobereiner, Newlands, Mendeleev and Moseley each improved the arrangement of the elements.
4. Mendeleev's gaps and predictions
   40 min · 1 practice tasks · quiz
   Empty boxes were not missing data - they were predictions, later filled by gallium, scandium and germanium.
5. Moseley and atomic number order
   40 min · 1 practice tasks · quiz
   Atomic number, not atomic mass, is the true order of the table and it fixed the awkward swaps.
6. Layout of the modern table
   40 min · 1 practice tasks · quiz
   s-block, p-block and d-block, and how Kenyan Grade 10 still names groups I to VIII.
7. Groups as chemical families
   40 min · 1 practice tasks · quiz
   A group is a vertical column of elements with the same number of outer electrons and similar reactions.
8. Periods and electron shells
   40 min · 1 practice tasks · quiz
   A period is a horizontal row; the period number is the number of occupied shells.
9. The first twenty elements on the table
   40 min · 1 practice tasks · quiz
   Place H to Ca by atomic number, write each arrangement, and read group and period from it.
10. Hydrogen's special position
    40 min · 1 practice tasks · quiz
    Hydrogen sits above group I because it has one electron, but it is a non-metal that can also behave like a halogen.
11. Metals, non-metals and metalloids
    40 min · 1 practice tasks · quiz
    The table splits into metals on the left, non-metals on the top right, and a staircase of metalloids.
12. What makes a metal
    40 min · 1 practice tasks · quiz
    Physical properties of metals, why they lose electrons, and everyday Kenyan examples.
13. What makes a non-metal
    40 min · 1 practice tasks · quiz
    Non-metals gain or share electrons, often form molecules, and include the gases of air and the halogens.
14. The metalloid staircase
    40 min · 1 practice tasks · quiz
    Metalloids sit on the zig-zag border and mix metallic look with non-metallic chemistry; silicon is the one to know.
15. The alkali metals
    40 min · 1 practice tasks · quiz
    Group I: one outer electron, stored under oil, reactivity with water increases down the group.
16. The alkaline earth metals
    40 min · 1 practice tasks · quiz
    Group II: two outer electrons, less reactive than group I, and Kenya's limestone and fluorspar.
17. The halogens
    40 min · 1 practice tasks · quiz
    Group VII: seven outer electrons, diatomic molecules, colour and state darken down the group, reactivity falls.
18. The noble gases
    40 min · 1 practice tasks · quiz
    Group VIII: full outer shells, almost unreactive, and the reason every other group forms ions.
19. The transition metals
    40 min · 1 practice tasks · quiz
    d-block metals: typical metallic properties, often coloured compounds and more than one ion, with Kenyan ores.
20. Trends in atomic radius
    40 min · 1 practice tasks · quiz
    Atoms get larger down a group and smaller across a period; extra shells versus extra nuclear pull.
21. Trends in ionisation energy
    40 min · 1 practice tasks · quiz
    First ionisation energy falls down a group and rises across a period - the opposite of atomic radius.
22. Trends in melting point
    40 min · 1 practice tasks · quiz
    Melting point depends on bonding: metals, giant covalent silicon, then simple molecules that melt low.
23. Trends in reactivity
    40 min · 1 practice tasks · quiz
    Metal reactivity rises down group I and II; halogen reactivity falls down group VII - same cause, opposite result.
24. Soda ash and salt from Kenya
    40 min · 1 practice tasks · quiz
    Lake Magadi soda ash and coastal salt are sodium compounds; the table tells you Na is always Na+ here.
25. Limestone and fluorspar
    40 min · 1 practice tasks · quiz
    Calcium carbonate for cement and calcium fluoride from Kerio Valley: group II meeting carbon and the halogens.
26. Kenyan metal ores
    40 min · 1 practice tasks · quiz
    Iron, titanium, gold and copper in Kenya: transition metals in the ground, read with the d-block.
27. Predicting properties from position
    40 min · 1 practice tasks · quiz
    Given only group, period and a neighbour, predict ion, formula, metal/non-metal and a reactivity comparison.
28. The table as a working tool
    40 min · 1 practice tasks · quiz
    Put history, position, groups, trends and Kenyan minerals together and use the table as chemists do.