Group 2 Flashcards
What are group 2 elements also known as?
Alkali earth metals.
What is a metallic radius?
Half the distance between the nuclei in a giant metallic lattice.
What is the trend of metallic radius in group 2 elements?
Metallic radius gets larger going down the group. This is because the outer two electrons occupy a new principal quantum shell that is further away from the nucleus.
What is the trend in melting point of group 2 elements?
It decreases as you go down the group.
What is the trend in density as you go down group 2 elements?
Density increases as you go down the group until you reach strontium where it increases to 2.6 and barium is 3.5
What is the oxidation number of group 2 elements?
+the metals act as reducing agents. Their atoms donate (give away) electrons and so they are oxidized themselves as they react to form their 2+ ions.
What is the trend in ionisation energy down group 2 elements?
Ionisation energy decreases
What is the trend in reactivity of group 2 elements as we go down the group?
The metals in group 2 get more reactive as we go down the group. It gets easier to remove the pair of outer electrons going down ther group, so although the positive charge on the nucleus increases the greater sheilding effect providedcby the inner shells of electrons and the larger distance of the outer most electrons from the nucleus outweighs the attraction of the higher nuclear charge. Thus the group 2 elements get more reactive going down the group.
How can the trend in group 2 elements reactivity be shown.
By looking at reactions of group 2 metals, magnesium to barium with dilute hydrochloric acid, forming a solution of the metal chloride and giving of hydrogen gas. You can see the reactions getting more vigorous descending the group by the increasing rate at which bubbles of hydrogen gas is given off.
What is the reaction of magnesium with dilute Sulfuric acid?
Mg(s)+H2S04 (aq) + H2(g)
Describe the reaction between calcium, strontium or barium and sulfuric acid.
Any reaction with calcium, strontium or barium is quickly stopped by the formation of an insoluble sulfate layer on the surface of the metals. For example you can see a slow stream of of hydrogen bubbles fta short time when a pellet (small piece) of calcium metal is dropped into dilute Sulfuric acid.
Ca(s)+H2S04 (aq)=CaSO4(s)+H2(g)
The calcium then gets completely covered by a layer sparingly soluble calcium sulfate and the bubbles stop rising from the metal. Strontium and barium sulfate are even less soluble than calcium sulfate so will quickly stop any reaction with the metals strontium and barium.
What is the trend in solubility of group 2 elements
Get less soluble going down the group
Describe how to conduct a flame test.
We can test for calcium stontium and barium ions in compounds using flame tests. A nichrome wire cleaned with a concentrated hydrochloric acid is dipped into a sample of the salt to be tested and heated in non-luminous bunsen flame.
What is the flame test result of calcium compounds?
Brick red color
What is the test result of strontium compound flame test?
Scarlet red color
