TOPIC 4 - Inorganic chemistry and the Periodic Table Flashcards
What is the general equation for the reaction between group 2 metals and water?
X + 2H2O > X(OH)2 + H2
What is the equation for the reaction of magensium with steam?
Mg (s) + H2O (g) > MgO (s) + H2 (g)
Why does reactivity increase down group 2?
Atom is larger so electron is further away from the nucleus and there is more shielding.
Therefore the electrostatic forces of attraction between the outer electrons and the nucleus decreases.
Therefore it is easier to remove the outer electrons and reactivity increases.
What is the general equation for group 2 metals with oxygen?
2X + O2 > 2XO
What appearance do group 2 oxides have?
White solids.
What is the general reaction for group 2 metals with chlorine?
X + Cl2 > XCl2
Why do group 2 metal oxides create an alkaline solutions?
XO + H2O > X(OH)2
X(OH)2 > X2++ 2OH-
The OH- ion creates the alkaline solution.
Which group 2 oxides don’t create alkaline solutions?
- Magnesium oxide - reacts very slowly with water and magnesium hydroxide is barely soluble.
- Beryllium oxide - doesn’t react with water and the hydroxide is insoluble.
Why do group 2 metal oxide solutions get more alkaline as we go down the group?
They are more reactive with water.
The hydroxide salt is more soluble so it dissociates more.
How does solubility of group 2 hydroxides change as we go down the group?
Increases
How does solubility of group 2 sulfates change as we go down the group?
Decreases.
What is the general equation for the thermal decomposition of group 2 carbonates?
What is the general formula for the thermal decomposition of group 2 nitrates?
Why does thermal stability of carbonates/nitrates increase as we go down group 1 or 2?
Bigger metal cation so lower charge density.
Therefore the electron cloud in the anion (sulfate/carbonate) is less distorted.
The less distortion, the more thermal stability.
Do group 1 carbonates decompose under bunsen flame?
No. Only Lithium carbonate.
What is the general equation for the thermal decomposition of group 1 nitrates?
What is the equation for the thermal decomposition of of lithium nitrate?
4LiNO3 > 2Li2O + 4NO2 + O2
Why are group 1 carbonates/nitrates more stable than in group 2?
Group 1 ions have a lower charge than group 2 (+1 vs +2) so they have a lower charge density.
Therefore the electron cloud in the anion is distorted less.
The less distortion, the more stability.
How can you test for thermal stability?
Measuring how much and how fast gas is produced from thermal decomposition.
Why do flame tests give different colours?
- Electrons absorb energy from the flame and become excited so they move to a higher energy level.
- When they drop back to their ground level, and emit a specific amount of energy through electromagnetic radiation.
- This electromagnetic has a specific wavelength and so the part of the spectrum that falls into visible light, has different colours.
What is the procedure for a flame test?
- Dip nichrome wire in HCl.
- Dip nichrome wire into sample.
- Place the loop into a blue bunsen flame and observe the colour.
What is the flame test colour of Li+?
Crimson red
What is the flame test colour of Na+?
Yellow/orange
What is the flame test colour of K+?
Lilac
What is the flame test colour of Rb+?
Red
What is the flame test colour of Cs+?
Blue
What is the flame test colour of Ca2+?
Dark red
What is the flame test colour of Sr2+?
Crimson red
What is the flame test colour of Ba2+?
Green
What is the flame test colour of Be2+?
No colour (radiation emitted doesn’t fall in the visible spectrum).
What is the flame test colour of Mg2+?
No colour. Radiation emitted doesn’t fall into the visible spectrum.
What is the appearance of Fluorine?
Pale yellow gas