Group 2 Metals Flashcards
Why does reactivity increase down group 2?
As you go down the group, the ionisation energies decrease - this is due to the increasing atomic radius and shielding effect. When group 2 elements react, they lose electrons forming positive ions. The easier it is to lose electrons, the more reactive the element.
How many electrons are in the outer shell of group 2 elements?
2
What is produced when a group 2 element reacts with water?
A metal hydroxide and hydrogen.
What is produced when group two elements react with oxygen?
They burn to produce solid white oxides.
What type of bonding do oxides and hydroxides contain?
Ionic bonding
How does the oxidation number for group 2 elements change when they react with water or oxygen and why does this change?
It goes from being 0 to +2 because 2+ ions are formed and they are oxidised
How does the oxidisation number of oxygen change when reacted with a group 2 metal?
Goes from 0 to -2
What kind of reaction is the reaction between group 2 elements and water or oxygen?
Redox reaction
What kind of solution does an oxide or hydroxide form when dissolved in water, and what gives the solution this property? How does this change down the group?
An alkaline solution, due to the hydroxide OH- ions. They become more alkaline down the group because the hydroxides get more soluble.
What is a cation?
A positive ion
What is thermal decomposition?
When a substance breaks down (decomposes) when heated.
What happens to thermal stability down the group 2 elements?
It increases down the group, so it takes more heat to decompose calcium than magnesium for example
What happens when a group 2 carbonate is decomposed?
They are heated to form a metal oxide + CO2
What are group 2 compounds used for?
To neutralise acidity.
Give two examples of how group 2 compounds are used to neutralise acids?
1) calcium hydroxide (slaked lime) Ca(OH)2 is used in agriculture to neutralise acid soils
2) magnesium hydroxide (Mg(OH)2) is used in some digestion tablets as an antacid.
