2.2 Group 2 metals Flashcards
Write an equation for the first ionisation energy of magnesium
Mg(g) –> Mg+ (g) + e-
Why does first ionisation energy increase across period 3
Because of nuclear charge, decreased atomic radius and same electron shielding means more energy is needed to remove the first electron
Dips at Al because outer electron is in a 3p orbital, higher energy than 3s orbital –> less energy needed to remove electron
Dips at S because one 3p orbital contains two electrons –> repulsion between paired electrons –> less energy to remove one
What happens to first ionisation energy as you go down group 2, why?
Decreases because number if filled electron shells increases down the group –> increased shielding, increased atomic radius –> weaker force between outer electron and nucleus –> less energy needed to remove electron
How does reactivity with water change as you go down group 2
Increases
Because outer electrons further from nucleus and more electron shielding, so electrons are lost more easily
Write an equation for the reaction of Barium and water
Ba(s) + 2H2O(l) –> Ba(OH)2 (aq) +H2 (g)
Write an equation for the reaction of magnesium and steam
Mg(s) + H2O –> MgO(s) + H2 (g)
What is the trend in hydroxide solubility down group 2
Increases down the group
Mg(OH)2 is almost insoluble
Ba(OH)2 creates a strong alkaline solution
What is the trend in sulphate solubility down group 2
Decreases down the group
MgSO4 is soluble
BaSO4 is insoluble
What is the trend in melting point down group 2 why
Decreases down group
Because sea of positive delocalised electrons is further from the positive charge of the nucleus –> weaker metallic bonds/FOA which take less energy to weaken
What is the trend in atomic radius down group 2
Increases as there are more occupied electron shells down the group
Write the equations for the
extraction of titanium using magnesium
TiO2 + 2Cl2 + C –> TiCl4 + C)2
TiCl4 (l) + 2Mg (s) –> “MgCl2 (s) + Ti (s)
What are flue gases
Gases produced by power stations which are harmful to the environment
How can CaO or CaCO3 be used to remove flue gases, write equationa
CaCO3 (s) + SO” (g) –> CaSO3 (s) + CO2 (g)
CaO (s) + SO2 (g) –> CaSO3 (s)
What is Ca(OH)2 used for
Write an equation for one of its uses
Used to neutralise soil
Ca(OH)2 (aq) + 2HCl (aq) –> 2H2O (l) + CaCl2 (aq)
What is Mg(OH)2 used for
Milk of magnesia - antacid to treat indigestion, heartburn, wind etc
What is a use of BaSO4, why is it safe
In barium meals to outline gut in X-rays
Ba2+ is toxic but is fine as barium sulphate is insoluble
How can BaCl2 be used to test for sulfate ions
Add to sample with HCl, white ppt will form is sulfate ions present
Ba2+ +SO4 2- -> BaSO4
