The Periodic Table
Science: KS3, topic 2.4.4
The Periodic Table of Elements
The periodic table of elements is a system of arranging the elements. All the elements found in the periodic table are elements. The elements could be found on any planet in the whole universe.
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The Elements
- There are 118 elements on the periodic table.
- 90 of the elements occur naturally.
- The rest are produced by man.
Element arrangement
- The elements are arranged by their increasing atomic number.
- Metals can be found on the left-hand side (of the dividing step line).
- Non-metals are found on the right-hand side.
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Groups
- The vertical columns of the periodic table are called groups.
- The large block in the middle is called the transition metals.
Group names
- Elements in each group can be named:
- Group 1: the alkali metals.
- Group 7: the halogens.
- Group 0: the noble gases.
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Properties of groups
- Elements in each group have similar properties and patterns to each other.
- Group 1, the alkali metals, are very reactive.
- The alkali metals get more reactive as they go down the group.
Halogen reactivity
- Group 7, the halogens, are also reactive.
- The halogens get less reactive as they go down the group.
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Periods
- The horizontal rows of the periodic table are called periods.
- Patterns can be seen as you go along the periods.
Period patterns
- The size of the atom decreases along the period.
- The decrease happens from left to right.
- The elements get less metallic as you go from left to right.
Test yourself on The Periodic Table
Which are true of the periodic table?
How many elements on the periodic table occur naturally?
What is the trend in reactivity down the alkali metals?
Element A and element B are in the same period. Element A is to the left of element B. Which statement is correct?