Zusammenfassung der Ressource
The Periodic Table
- Early periodic
Table
- Medeleev/Newlands
- Both arranged
elements by their
ATOMIC WEIGHT
- the list was arranged in a able so
elements with similar properties
were in the same groups
Anmerkungen:
- newlands discovered the law of octaves but If the atomic weight was strictly followed it only worked until calcium
- Mendeleev realised that some
had not yet been discovered and
left gaps for them
- Modern
Periodic Table
- electrons/protons/neutrons all
discovered in the early 20th
centuary
- now we arrange by
atomic (proton) number
- now all elements
are in the
appropriate places
- a table arranged in
terms of electronic
structures
- Group 1-
alkali metals
Anmerkungen:
- further down = more reactive, also means it has a lower melting point and boiling point
- low density
- react with
non-meatals to form
ionic compounds
- form 1+ ions
- form chlorides
- white solids, dissolve in
water to form colourless
solutions
- react vigorously with water, releasing hydrogen
- when reacted with water form hydroxides,
they are soluble in water and give an alkali
solution
- Transition elements
- ductile
- good conductors
- hard+strong
- malleable
- high densities
- high mp/bp apart
from mercury
- less reactive and don't
react as vigorously w/ water
or oxygen
- form coloured compounds as they
have different ions e.g. Fe1 and Fe3
- good catalysts
- Halogens
- react w/ metals to
form ionic
compounds
- Halide ion
carries
charge of -1
- further down the group
the element is...
- less reactive
- higher mp/bp
- more reactive halogen can displace a less reactive
halogen from an aqueous solution of it's salt
- trends in the table can be
explained by the energy
levels
Anmerkungen:
- more shells = electrons easly lost and less are easily gained