C4 - The Periodic Table
- Created by: Lilly_B
- Created on: 31-03-15 17:59
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- C4 - The Periodic Table
- Creation of the Periodic Table
- Early 1800s - Dobereiner notices several groups of three elements with similar properties
- Newlands arranged the elements in order of relative atomic mass
- Every eighth element had similar properties
- His pattern only worked for the first 16 elements
- Mendeleev Showed there were patterns in the properties of all of the elements when arranged in relative atomic mass order
- He made a sensible pattern by leaving gap for missing elements
- He predicted the missing elements' properties & scientists later found these missing elements
- Introduction to the Periodic Table
- The elements are arranged in order of proton number
- There are repeating patterns in the element's properties
- The vertical columns are called groups & elements in a group have similar properties
- The horizontal rows are called periods
- The elements to the left of a stepped line between aluminium, silicon, and so on have special properites.
- The elements to the left of the stepped line are metals.
- Group 1: the alkali Metals
- Alkali metals include the elements: lithium (Li), Sodium (Na), & potassium (K)
- They have low densities, so they float on water
- They have low melting & boiling points
- They're shiny when freshly cut
- They quickly tarnish in damp air as they react with oxygen
- Alkali metals react with water to make hydrogen & an alkaline solution
- Going down the group, the reactions get more vigorous.
- Alkali metals act vigorously with chlorine gas to make chlorides
- the chlorides are colourless crystalline solids
- Group 7: the Halogens
- Halogens include the elements:
- Chlorine - a pale green gas (Cl)
- Bromine - a deep read liquid with brown vapour (Br)
- Iodine - a grey solid with purple vapour (I)
- Going down the group, melting point & boiling point increase
- Halogen molecules are diatomic- they're made from two atoms joined together
- Going down group 7, the elements become less reactive
- When one halogen is put into a reaction with another halogen which is less reactive then the newly-added halogen, it can displace it.
- Halogens include the elements:
- Creation of the Periodic Table
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