Topic 4- Inorganic Chemistry And The Periodic Table Flashcards
(33 cards)
What’s the trend in ionization energy down group 2?
Ionization energy decreases:
- as the number of inner shells increases, their force of attraction on the e- being removed decreases.
- as each quantum shell is added, the energy of the outermost electrons increases.
- nuclear charge increases force of attraction increases, IE increases. (This factor is outweighed)
What is the trend in reactivity down group two?
General increases because of the decrease in energy required to remove two electrons from each atom of the element.
What happens when group two elements react with oxygen?
- when Mg burns in air, bright flame and white solid.
- Ca, Sr, Ba, are heated in air, the reactions are more vigorous.
What is the general formula for when a grp2 metal reacts with oxygen.
2M (s) + O2 (g) —> 2MO (s)
What happens when grp 2 elements react with chlorine?
- they combine with Cl when heated in the gas.
- More vigorous down the group.
What’s the general formula for when grp two elements react with chlorine?
M (s) + Cl2 (g) —> MCl2 (s)
What happens when grp two elements react with water?
- very slow, doesnt proceed completely.
- Ca, Br, Ba react with increasing vigor, this can be seen by the increase in effervescence.
What happens when group 2 OXIDES react with water?
They form alkali’s
They form colorless solutions
What’s the general equation for the reaction of group 2 oxides with water?
MO + H2O -> M(OH)2
Explain the trends in solubility of group 2 HYDROXIDES:
Increases down the group (ions get larger, forces holding them together weaken), pH value down the group also increases.
CHARGE DENSITY DECREASES
What’s the reaction of group 2 oxides and hydroxides with acids?
They react to form salt and water in a neutralization reaction.
White solid forms colorless solution
Explain the trends in solubility of group 2 SULFATES:
Decreases down the group.
MgSO4- soluble
CaSO4- slightly soluble
Sr+BaSO4- insoluble
How to test for sulfate ions?
Add a solution containing barium ions, they react to form a white precipitate. But, there must be H+ ions present (nitric or hydrochloride acid) to prevent the barium carbonate from forming as a white parcipitate.
What happens when group 2 nitrates and carbonates are heated?
They dont melt- they decompose.
What happens when a nitrate ion decomposes?
It can change into nitrite or oxide ion by releasing oxygen gas and/or nitrogen dioxide.
What happens when a carbonate ion decomposes?
It can change into an oxide ion by releasing CO2
What is the stability of nitrate and carbonate ions influenced by?
The charge and size of cation present.
Explain the thermal stability of nitrates
Group 1 and 2 nitrates are white solids.
Decomposes to give NO2 (brown fumes) and / or O2
NO BROWN FUMES- LESSER DECOMPISITION: GROUP 1
Metal nitrate -> metal nitrite + oxygen
BROWN FUMES- GREATER DECOMPOSITION: GROUP 2
Metal nitrate-> metal oxide + nitrogen dioxide + oxygen
What can be observed in the decomposition of group 1 and group 2 nitrates?
Group 1- no brown fumes except lithium
Group 2- all brown fumes
Explain the thermal stability of carbonates
All group 1 and 2 carbonates are white solids.
Decompose to oxides and gives off CO2
No observation because the gas is colorless
What does a high charge density mean for nitrates and carbonates?
Less thermal stable because it can polarize the carbonate or nitrate ion more.
What determines charge density?
Size and charge of ion
What is the general trend for MP AND BP in group 7 ?
Depends on the IMF of attraction between the molecules.
Increases down the group
London forced are the forces that exist between halogen molecules.
Force increases as the number of e- and size of e- cloud increases.
What is the general trend in reactivity down group 7?
Decreases down the group.
