Group 2 Metals Flashcards
What are group two metals also known as?
The alkaline earth metals.
What bonding occurs in G2?
Metallic.
Starting from Be list G2 to Ra.
Be, Mg, Ca, Sr, Ba, Ra.
Trend of atomic radius down G2?
Increases.
Why does atomic radius change down G2?
More principal energy levels are occupied. These levels are further from the nucleus and additional shells shield the outer e-s from the nuclear charge. The outer e-s are attracted less strongly the further from the nucleus they are.
Trend of 1st ionisation energy down G2?
Decreases.
Why does the 1st ionisation energy change down G2?
Outer e- is removed more and more easily, e- is removed from a successively higher principal energy level further from the nucleus. More shielding/ no. of energy levels between the outer shell and the nucleus. Extra inner e-s shield the outer e-s from the increased nuclear charge so less energy is needed to remove it.
Trend of m.p and b.p down G2?
Decreases.
Why does m.p and b.p change down G2?
All metallically bond and each atom gives 2 e-s into the structure, the attraction between the + ion and - e-s hold the metal together, the stronger the attraction the higher the m.p. The + ions get bigger down the group and the extra shells of e-s shield the attraction of the metal ion nuclei and the free e-s. Metallic bonds get easier to break and m.p is lower.
What element is the exception to the m.p trend in G2?
Mg.
Why is Mg lower m.p?
Has a different metallic structure.
How does Mg react with water?
Reacts very slowly with cold water, readily with steam.
Equation for Mg and water?
Mg(s) + H2O(g) -> MgO(s) + H2(g).
How does Ca react with water?
Reacts with cold water.
Equation for Ca and water?
Ca(s) + 2H2O(l) -> Ca(OH)2(aq) + H2(g).
How does Sr react with water?
Reacts quickly with water.