Unit1Topic6 - The Periodic Table Flashcards
The Newlands structure of the Periodic Table
- arranged elements in order of increasing atomic mass
- noticed similarities between each 8th element (called the Newlands Octaves)
The Mendeleev structure of the Periodic Table
- left gaps for undiscovered elements
- arranged elements in groups and periods
- separated the metals and non-metals
- arranged elements in order of increasing atomic mass
How the modern Periodic Table differs from Mendeleev
- no gaps
- noble gases
- elements arranged in order of atomic number
- actinides and lanthanides
Name of group 1
Alkali metals
Name of group 2
Alkaline earth metals
Name of group 7
Halogens
Name of group 8
Noble gases
Name of block between groups 2 and 3
Transition metals
Which elements are the only liquids on the Periodic Table?
Br and Hg
Across a period the…
- atoms decrease in size
- elements change from metals to non-metals
- oxides of the elements change from basic to acidic
- semi-metals (properties between metals and non-metals) are found between metals and non-metals e.g. silicon
Why do the atoms gradually decrease in size across a period?
The extra electron going into the same shell and the extra positive charge on the nucleus, caused by the extra proton, increases the attraction on the shells pulling them closer to the nucleus.
As you go down groups 1 and 2…
- bigger atoms (there is one extra full shell of electrons for each row you go down)
- more reactive (outer electron is more easily lost as further from the nucleus)
- more dense
- even softer to cut
- lower melting point / boiling point
Metal + water ->
Metal hydroxide + hydrogen
Metal + oxygen ->
Metal oxide
Metal + acid ->
Salt + hydrogen
Metal + halogen ->
Metal halide
Potassium in water observations
- bubbles of gas / fizzes
- moves across surface
- potassium disappears
- catches fire / burns with a lilac flame