Unit 6 The periodic table

Alkali metal

Alkali metal - Group I elements

Alkaline earth metal

Alkaline earth metal - Group II elements


Anion - a negatively charged ion (negative ion)


Cation - a positively charged ion (positive ion)


Group - the vertical columns in the periodic table


Halogen - Group VII elements


Ion - formed when an atom either loses or gains one or more electrons and is either positively or negatively charged

Noble gas

Noble gas - a chemically inert gaseous element belonging to the same group (Group 0) as helium in the periodic table; noble gases in the air include argon, helium, neon, krypton and xenon

Octet rule

Octet rule - atoms become stable by having eight electrons in their outermost shells


Period - the horizontal rows in the periodic table

Periodic table

Periodic table - a table in which all chemical elements are arranged in order of increasing atomic number


Reactivity - how readily an element reacts with another element


Salt - a compound formed between a metal and a non-metal

Transition metal

Transition metal - elements between Groups II and III of the periodic table

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