topic 4 Flashcards
what happens to the atomic radius down a group and why
increases
extra shells added
what do all group 2 metals have at the end of electronic configuration
S2
what happens to ionisation energy down group 2 and why
decreases
more shielding
increase in protons overriden by sheilding
how do G2 react with water
form bases
metal hydroxides
Sr + H2O –> Sr(OH)2 + H2
what happens to reactivity with water down group 2 and why
increases
atoms get larger
more shielding
how does Mg react with cold water and steam
slowly with cold water
more vigorously with steam producing magnesium oxide
how do G2 react with oxygen using Mg as example
metal oxides
2Mg + O2 –> “MgO
Mg oxidised
O reduced
how does G2 react with chlorine using Mg as example
metal chlorides
Mg + Cl2 –> MgCl2
Mg oxidised
Cl2 reduced
how do G2 oxides react with water
form bases
SrO + H2O –> Sr(OH)2
more alkaline down group and hydroxides become more soluble
how do group 2 oxides react with HCl using calcium oxides as example
neuralisation
CaO+ 2HCl –> CaCl2 + H20
how do group 2 hydroxides react with HCl using calcium hydroxide as example
Ca(OH)2 + 2HCl –> CaCl2 + 2H2O
neutralisation
what happens to the solubility of G2 sulfates and G2 hydroxides down the group
sulfates SO4 2-
less soluble
hydroxides OH-
more soluble
how do G2 carbonates decompose using calcium carbonates as example
metal oxides + carbon dioxide
CaCO3 –> CaO + CO2
how do G2 nitrates decompose using calcium nitrate as an example
metal oxides + nitrogen dioxide + oxygen
2Ca(NO3)2 –> CaO + 4NO2 + O2
what is the trend in thermal stability down group 2 and why
more thermally stable down
lower charge density so less distortion
are G1 compounds more or less thermally stable than G2 and why
more
+1 charge so less distortion
do G1 carbonates decompose
no thermally stable except lithium
Li2CO3 –> Li2O + NO2 + O2
how do G1 nitrates decompose with lithium nitrate and potassium nitrate as examples
for nitrites and oxygen
LiNO3 –> Li2O + NO2 + O2
2KNO3 –> 2KNO2 + O2
how to measure thermal stability of nitrates
NO3 -
how long it takes for specific amount of O2
gas syringe or relight glowing splint
length of time for specific amount of NO2
brown toxic gas
how to measure thermal stability of carbonates
CO3 2-
length of time for specific volume of CO2
turns lime water cloudy
gas syringe
how to carry out a flame test
- dip nichrome wire in conc. hydrochloric acid
- dip into sample
- place loop into blue busen flame and observe colour change
why do you get different colours on the flame tests
electrons move to higher energy levels as they absorb energy from the flames
when they drop back down light is released
difference in energt levels determines wavelength of light energy released