C2 - the periodic table Flashcards
how did john dalton order the periodic table ?
in order of atomic weight
what did john newlands notice about daltons table?
every 8th element seemed similar
what was wrong with newlands’ table?
he didn’t leave space for undiscovered elements, so his ideas about the 8th elements seeming similar made no sense in his table
what did mendeleev do differently in his table?
he arranged them so that a periodic pattern in their properties could be seen
he left spaces for elements that had not been discovered
how are elements ordered today?
by atomic number
what are the properties of metals and non metals ?
metals - conductors, higher melting and boiling points, ductile, malleable, lustrous
non metals - insulators, brittle
properties of noble gases
monoatomic (single atoms), gases, highly unreactive, do not tend to form molecules
properties of alkali metals
highly reactive (reactivity INCREASES as you go down), low density, very soft, silvery shiny surface until they react with oxygen, lowish melting points
what happens when you add lithium, sodium, or potassium to water
the metals floats and fizzes (due to hydrogen gas being formed)
potassium reacts so vigorously the hydrogen ignited burning lilac
properties of the halogens (group 7)
toxic, coloured vapours, low melting and boiling points (increase as you go down the group), poor conductors of heat and electricity, diatomic (only exist in F2, Cl2, Br2)
what is the displacement rule
a more reactive halogen will displace a less reactive halogen from solutions of its salts
why does reactivity increase down group 1?
atoms get larger so the single electron in the outer shell is less attracted to the positive nucleus, so it is lost more easily
why does reactivity decrease down group 7?
because it is harder to gain an electron due to the outer shell being further away from the positive nucleus
what are the properties of the transition metals ?
good conductors
high densities
high melting points (bar mercury)
less reactive than group one
what are some common compounds of transition elements?
copper sulfate (blue)
nickel carbonate (pale green)
chromium oxide (dark green)
manganese chloride (pale pink)
