Groups in The Periodic Table Flashcards
What are alkali metals properties?
Alkali metals properties: soft and have relatively low melting points.
Describe the reactions of lithium, sodium and potassium with water
Lithium - Fizzes steadily
Sodium – Melts into a ball the fizzes quickly.
Potassium - Gives off sparks and hydrogen burns with a lilac flame.
They react vigorously with water to create an alkaline metal hydroxide and hydrogen.
Describe the pattern of reactivity of the alkali metals
Down the group – easier to lose electrons and form positive metal ions (cations) (these are formed when metals react). It is easier to lose electrons due to the increase in electron shells as you go down the group. This means there is more electron shielding and so decrease in attraction between the positively charged nucleus and the negatively charged outer shell electrons, which can then be lost more easily. This therefore means , the reactivity of all alkali metals increases down the group.
Recall the colours and physical states of chlorine, bromine and iodine at room temperature
Chlorine is a green gas.
Bromine is a red-brown liquid.
Iodine is a purple solid.
Describe the physical properties of halogens
There is a trend in state from gas to liquid to solid down the group. This is because the melting and boiling points increase as you go down the group.
Describe the chemical test for chlorine
When damp litmus paper is put into chlorine gas the litmus paper is bleached and turns white.
Describe how halogens react with metals
Reaction is less vigorous as you move down group but they still react form metal halides.
Describe how halogens react with hydrogen
Halogen + hydrogen → hydrogen halide
Reaction becomes less vigorous down the group.
Hydrogen halides dissolve in water to produce acidic solutions – in solution the hydrogen halide will fully dissociate into H+ and halide ions.
Describe the reactivity series of halogens
A more reactive halogen can displace a less reaction in an aqueous solution of its salt.
This is because as you go down the periodic table:
Outer shell becomes further from the nucleus.
Electron shielding increases
Attraction decreases between nucleus and outer electrons.
Electrons are gained easily.
Halogens become less reactive.
Why are the noble gases chemically inert?
They have 8 electrons in their outer shell (except helium). Their electronic configurations demonstrate their full outer shells and this makes them unreactive because they are very stable.
Describe how the uses of noble gases depend on their inertness, low density and/or non-flammability
Low density = Helium used in balloons and airships since it is much less dense than air, so balloons filled with it float upwards.
Inertness & non-flammability = argon, krypton and xenon inside light bulbs, stops the filament burning away.
Inertness = argon used as a shield gas during welding, it is also denser than air which keeps it away from the metal.
Describe the pattern in the physical properties of some noble gases
The boiling points of the noble gases increase with increasing relative atomic mass (going down the group).
The densities of the noble gases increase as you go down the group.
