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PERIODIC TABLE, HISTORY, IMPORTANT GROUPS, TRANSITION METALS - Coggle…
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HISTORY
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EARLY ATTEMPTS
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Dobereiner created "Triads" in 1829, groups of 3 elements with similar properties
Newlands proposed the Law of Octaves in 1864 :every 8th element had similar properties This only worked for some elements
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MODERN TABLE
The elements are now arranged by increasing atomic number, not mass
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Protons, electrons and isotopes are now known, and have helped to shaoe the table
IMPORTANT GROUPS
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GROUP 7: THE HALOGENS
Fluorine, Chlorine, Bromine, Iodine , Astatine and Tennessine (depending on who you ask, tennessine is sometimes not included
When halogens reacts with metals, they produce a wide range of salts
Halogens are the only group that contain elements in three of the main states of matter at room temperature
Halogens have 7 electrons on their outer shell, also making them highly reactive
As you go down the group, the elements become less reactive, as the distance from the nucleus makes it harder to attract the last electron necessary to complete the outershell
They form anions , or :heavy_minus_sign: 1 charged ions
GROUP 0: THE NOBLE GASES
Helium, Neon, Argon, Krypton, Xenon, Radon, and sometimes Oganesson
Noble gases are inert, meaning they tend not to react
This is because they already have a full outershell of electrons, so do not need to lose or gain one
Their properties include being odorless, colourless and monatomic
TRANSITION METALS
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Their properties include: good thermal conductivity, good electrical conductivity, most are hard and strong, and have high melting and boiling points
They often form useful alloys, and are sometimes used as catalysts in reactions