The Periodic Table Flashcards
John Newlands’ contribution
every eighth element had similar properties when arranged by atomic weight
Dmitri Mendeleev’s contributions
- The elements are arranged in order of increasing atomic mass
- The horizontal rows are called periods
- The vertical columns are called groups
- Elements in the same group are similar to each other
why did Mendeleev leave gaps
he was aware that not all elements had been discovered
shell one
2 electron capacity
shell two
8 electron capacity
shell three
8 electron capacity
period number
number of shells
group number
number of electrons in outermost shell
atomic number
total number of electrons in all shells
group 0
(group 8) the noble gases
physical properties of group 0
- non-metal elements
- low boiling points, but increase down the group
- stronger intermolecular forces going down (larger atoms)
chemical properties of group 0
- extremely unreactive
- already have full outer shells
group 1
alkali metals
physical properties of group 1
- soft - can be cut with a knife
- low melting points, but decrease down the group
- low densities
chemical reactions of group 1 in water
- reactions get more vigorous down the group
- effervescence
- melting in some cases
- will eventually fizz away and disappear
- burns with sparks from potassium downwards
chemical reactions of group 1 with oxygen
- react with oxygen in the air to form metal oxides
- burn vigorously when heated - oxide forms as a white smoke
- forms a white oxide on surface of metal at room temperature
reactivity of group 1
increases down the group
chemical reactions of group 1 with chlorine
- react vigorously with chlorine to form chlorides
- chlorides are solids at room temperature
- chlorides dissolve in water to form colourless solutions
why does reactivity increase down group 1
- each of its atoms loses its outer electron to form a positively charged
ion - The more easily the ions form the more reactive the metal
group 7
the halogens
physical properties of group 7
- all diatomic - exist as simple molecules
- melting points and boiling points increase down group 7 - stronger intermolecular forces (more energy required)
chemical properties of group 7
- halogens react with metals to form salts - held together by ionic bonds
- reactivity decreases down the group
group 7 displacement reactions
more reactive halogens can displace less reactive halogens
