C2 Flashcards
John Dalton Periodic Table
Arranged by atomic weight
20 elements
John Newland Periodic Table
Arranged by mass
Every eighth element seemed similar
Produced law of octaves without gaps for undiscovered elements
Dmitri Mendeleev Periodic Table
Placed in order of atomic weight
Organised in regular pattern
Left room for undiscovered elements
Elements in same group
Same amount of electrons in outer shell
Metals in periodic table
Left side and centre
Group 1,2,3 loose electrons to form positive ions
Non metals
Top right - hand corner
Group 5,6,7 gain electrons to from negative ions
Group 0
Full outer shells
Exist as monatomic
Unreactive
Boiling point increases as you go down
Properties of alkali metals
Very reactive - stored in oil
Reactivity increases as you go down
Low density
Shiny but dull in oxygen
Melt and boil at low temps
Melt and boil points decrease as you go down the group
Alkali metals reaction with water
Lithium, sodium and potassium float and fizz - hydrogen gas
Potassium ignites in a purple flame
Word equation for water and alkali metal
Alkali + water -> metal hydroxide + hydrogen
Group 7 name
Halogens
Halogens properties
Low melting and boiling points - increase as you go down
Poor conductors
Diatomic
Less reactive as you go down
Halogens displacement
More reactive displaced less reactive
Explaining reactivity trend in group 1
Larger atoms lose electrons more easily because:
- outer shell further away from the nucleus so force is weaker
- shells of electrons shield force from nucleus
Explaining reactivity trend in group 7
Larger atoms gain electrons less easily because:
- outer shell further from nucleus so attracting force is weaker
- shells of electrons shield force from nucleus (other electrons aren’t as attracted)
