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Chemistry - The Periodic Table - Coggle Diagram
Chemistry - The Periodic Table
History
John Dalton (1808)
ordered 36 elements
symbol for each
Dimitri Mendeleev (1869-1871)
listed known elements in rows or columns of atomic weight
started new row when element’s characteristics were repeated
left gaps
predicted properties of undiscovered elements
make pattern fit
swapped elements
if properties suggested it should be changed
confirmed by isotopes
Early 1800s
Arranged
physical and chemical properties
Atomic Weight (relative atomic mass)
only thing they could measure
not complete
some elements in wrong group
Modern
organised in order of increasing atomic (proton) number
repeating patterns in properties of elements
elements with similar properties
groups
columns
rows
periods
new period
another electron shell
Group number
amount of electrons in outer shell
similar reactivity
Group 1 - Alkali Metals
Properties
soft
increases going down
cut by a knife
low density
low melting and boiling points
good conductors
shiny
very reactive
Going down Group 1
outer electron - further from the nucleus
more shells
electrostatic attraction from nucleus - weaker
positive charge pulling on electrons
shielded by shells
outer electron held less tightly
more easily lost in chemical reactions
Reaction with water
fizzing
metal reacts with water
hydrogen
metal hydroxide
high pH
universal indicator
purple
Sodium + Water -> Sodium hydroxide + hydrogen
Metals and Non-metals
Metals
form positive ions when they react
Properties
strong
malleable
good conductors
high melting and boiling points
Non-metals
Properties
dull
brittle
aren’t always solid at room temp
poor conductors
low density