Chapter 8 Reactivity Trends Flashcards
what is the name of the group 2 elements
alkaline earth metals
what ions do group 2 elements form
2+ cations
explain the reactivity trend in group 2
reactivity increases down the group because it becomes easier to lose electrons due to increased electron shielding and larger atomic radius
what type of agent are group 2 elements very good at
reducing agents
how does the solubility of group 2 elements change for 1- ions such as OH-
solubility increases down the group
how does the solubility of group 2 elements change for 2- ions such as CO3 2-
solubility decreases down the group
what is the sulphate ion test
add Barium to the solution and wait to see if a white barium sulphate precipitate
what is the metal acid word equation
Metal + Acid –> Salt + Hydrogen
what is the metal oxygen word equation
Metal + Oxygen –> Metal oxide
how does thermal stability change down a group
thermal stability increases down a group
what is the test for a carbonate
add an acid and see if there is any effervesence
what is the test for halides
adding AgNO3 first to see a precipitate form
then adding dilute and concentrated ammonia solutions
what are three precipitates formed by adding silver nitrate
chloride - white
bromide - cream
iodide - yellow
which halide solutions dissolve in dilute ammonia
chloride
which halide solutions dissolve in concentrated ammonia
chloride
bromide
what colour precipitates do halogens form in water
chlorine - pale green
bromine - orange
iodine - brown
what colour precipitates do halogens form in an organic solvent like cyclohexane
chlorine - pale green
bromine - orange
iodine - violet
why do halogens in water form two immiscible layers when an organic solvent is added
the two non polar substances halogens and organic solvents form a top layer due to their mutual attraction
meanwhile the two polar substances te halide ions and the water mix to form a bottom layer
how and why does oxidising power change in group 7
oxidising power decreases down group 7 due to increased electron shielding and larger atomic radius which decreases the electrostatic attraction
what is disproportionation
redox reaction where same element is both oxidised and reduced
what is a qualitative test
test where you look for a change that can be observed and then interpreted this could be a colour change for example
what is the test for ammonium
add aqueous sodium hydorxide and moist pH indicator paper. If ammonia is present then you should smell ammonia gas and see the indicator turn blue
what is the order of qualitative tests
carbonate test
sulphate test
halide test
why must the carbonate test be done before the sulphate test
Because Barium + carbonate also forms a white precipitate the same as a sulphate however in the carbonate test only a carbonate would give off effervesence
why must the halide test be done last
because both carbonates and sulphates form a white precipitate with the silver ions from silver nitrate solution which would mislead you to think it was chloride
if you only had one test tube with a mixture if substances in it was is the first step to identifying the different chemicals inside
do the carbonate test adding excess acid until no more effervesence is produced so that you are sure all carbonate has been removed
if you only had one test tube with a mixture of substances in it was is the second step to identifying the different chemicals inside
do the sulphate test to see if a white precipitate forms and add excess barium ions then filter out the precipitate to make sure all sulphate is removed
if you only had one test tube with a mixture of substances in it was is the third step to identifying the different chemicals inside
do the halide test adding silver nitrate to see what colour precipitate forms then add ammonia solutions to double check
