topic 7 - groups in the periodic table Flashcards
what are the 6 metals in group 1
lithium potassium sodium rubidium caesium francium
what are 2 physical properties of alkali metals
very soft (cut with a knife) relatively low melting and boiling points
what do alkali metals form
readily lose their single outer electron to form 1+ ions with a stable electronic structure or form ionic compounds
what are the group 1 elements called
the alkali metals
what is the reactivity of group 1 like as you go down and why
the reactivity of the metals increases, as you go down the group
this is because the outer electron is more easily lost due to the atomic radius being larger so they are less strongly attracted to the nucleus
what happens when alkali metals react with water
they react vigorously to produce hydrogen gas and a metal hydroxide
the further down the group, the more violent the reaction becomes
how does lithium react with water
moves around on surface
fizzes furiously
how does sodium react with water
melts to form a ball that moves around on the surface fizzing rapidly
hydrogen produced may burn with an orange flame before sodium disappears
how does potassium react with water
metal melts and floats, moving across surface quickly
ignites quickly with sparks and a lilac flame, sometimes giving a small explosion at the end of the reaction
what are the group 7 elements called
halogens
trends in group 7
as you go down:
melting and boiling points increase
colours get darker
what colour and state is chlorine
green gas
what colour and state is bromine
red-brown liquid giving off orange vapour
what colour and state is iodine
dark grey crystalline solid that gives off a dark purple vapour if heated
group 7 elements exist as diatomic molecules ; what does this means
they share one pair of electrons in a covalent bond, giving both atoms a full outer shell
what is the test for chlorine
hold a piece of damp blue litmus paper over the gas
if it bleaches to white, chlorine is present
how does reactivity change as you go down the group 7 elements and why
reactivity decreases as it is harder to attract the electron to fill the outer shell as it is further away from the nucleus
metal halides
salts formed by reacting halogens with metals
hydrogen halides
soluble gases which dissolve to form acidic solutions
displacement reaction
a reaction where a more reactive element displaces a less reactive element from a compound
how are halogen displacement reactions redox reactions (what is reduced, what is oxidised)
halogens gain electrons (reduced)
halide ions lose electrons (oxidation)
how do you use displacement to discover reactivity trends (4)
1) measure a small amount of halide salt solution into a test tube
2) add a few drops of halogen solution and shake gently
3) if there is a colour change, a reaction has occurred
4) repeat with different combinations of halide salt and halogen
what are the group 0 elements called
noble gases
properties of noble gases
colourless gases at room temperature
all monatomic
more or less inert (unreactive) - therefore non flammable
