本题目来源于试卷: Classification of Matter A.1 Periodic Table Elements Classification，类别为 IB化学
[问答题]
The period 3 elements magnesium pugo/k3c.t41i7 sw pq, silicon and sulfur are *5 pipbmcg/jo9 9f1qafound in the second, fourteenth and*fc moj/1 i9bgq9a5pp sixteenth columns of the periodic table.
1.State the name given to a column of elements in the periodic table.
2.State how the numbers of electron shells and outer shell electrons vary across period 3.
3.Selected physical properties of magnesium, silicon and sulfur are given in the table below:
Element is Magnesium ; Appearance is Shiny, grey ; Mechanical properties is Ductile
Element is Silicon ; Appearance is Shiny, grey ; Mechanical properties is Brittle
Element is Sulfur ; Appearance is Dull, yellow ; Mechanical properties is Brittle
Explain how the positions of the elements across period 3 help to explain their similarities and differences.
4.Period 3 contains more elements than period 1 but is equal in size to period 2. Suggest why the number of elements increases between periods 1 and 2 but not between periods 2 and 3.
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