GCSE periodic table Flashcards
(27 cards)
describe the development of the periodic table
atoms suggested by Democritus in 400BC, ideas rediscovered by john Dalton, in 1864 John Newlands arranged the elements in order of mass (he produced the law of octaves), in 1869 Mendeleev published his periodic table
what did Mendeleev change?
- left gaps
- ordered elements based on atomic number
- predicted the theoretical properties of elements
why was Newlands table not accepted by his peers
-it was linked to heavily to the piano and was deemed unscientific
-in some cases there are two elements in one box
-it broke down past calcium
how did mendeleev justify changing how he ordered the elements
the groups were based on properties and he claimed they were measured incorrectly
what are the differences between Mendeleev’s table and the modern periodic table
-addition of noble gases
-Mendeleev based his table on atomic mass, now it is based on atomic number
-more groups added
what is the name of the group 1 elements
the alkali metals
what is the name of the group 2 elements
the alkali earth metals
what is the name of the group 7 elements
the halogens
what is the pattern of the hardness of alkali metals as you go down the group
these metals are soft and they get softer the further down the group you get
what is the density of the alkali metals
they all have very low density. lithium sodiium and potassium have such low density they can float on water
what is the pattern of boiling points as you go down the group in alkali metals
the melting and boiling points are low, they decrease as you go down the group
what does the pattern of melting and boiling point in the alkali metals tell you about the metallic bonds
the metallic bonds are stronger in the elements higher up as the forces of attraction are stronger over a smaller area
why are the group 1 metals stored in oil
they would react with the oxygen in the air
what happens when the alkali metals are cut
the cut face tarnishes within seconds as it reacts to the oxygen in the air
how does lithium react with water
fizzes and skates
how does sodium react with water
melts into small ball, fizzes and skates
how does potassium react with water
the hydrogen produced is set alight
how does rubidium react with water
instantly set alight
how does caesium react with water
explodes
what happens to reactivity of the alkali metals as you go down the group and why
as an atom has more shells, the distance between the outermost electron and the nucleus increases meaning the forces of attraction are weaker. it is easier to lose the outermost electrons
what are the common features of all group 1 compounds
-all ionic
-white (solid)
- soluble
-in solution they are colourless
what kind of molecules do the halogens form
diatomic
what bonds exist between halogen atoms
covalent bonds
why do the boiling points of the halogens get higher as you go down the group
it is a simple molecular substance, the intermolecular forces must be broken (rather than overcome like bonds). the intermolecular forces must be stronger as you go down the group
