Elements and the Periodic Table

Question	Answer
Elements	Substances that cannot be borken down into simpler materials.
Atomic Number	Number of protons
Group	Vertical
Period	Horizontal
Right of stepped line	Non-metals
Left of stepped line	Metals
Group 1	Alkalis
Group 2	Alkaline Earth Metals
Group 7	Halogens
Group 8	Noble Gases
Alkali Metals physical/chemical properties	soft, silver metals, low density reactivity increases doen the group, react with water forming hydroxide and hydrogen and with air to form oxide
What are alkali metals stored in and why?	Oil - to prevent reaction with atmospheric oxygen or with water
Alkaline earth metals physical/chemical properties	silver metals, harder then alkali metals less reactive than corresponding alkali metals, reactivity increase down the group
Halogens physical/chemical properties	Non-metals, low melting and boiling points very reactive, reactivity decreases down the group, react with hydrogen giving compounds which dissolve in water to form acidic solutions, react vigorously with sodium and other alkali metals giving white salts
Noble Gases	gases at room temperature, boiling point and density increases going down the group least reactive, inert gases
Dmitri Mendeleev	He organised his table according to his 'periodic law' : Elements are arranged in order of atomic weight in such a way that elements with similar chemical properties are in the same group.
Mass number	Total number of protons and neutrons

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	Created by eimearkelly3 almost 9 years ago

	Copied by Peter Hoskins almost 9 years ago