Group 2 metals are also called alkaline earth metals. They can make lots of different compounds that are useful in everyday life, like for medical tests and chemical analysis. But, how do these compounds form? And why are they so useful?
First, let's talk about what group 2 elements are and what they do. Then, we'll show you some examples of group 2 compounds. After that, we'll explain what happens when group 2 compounds react with water and acid. We'll also talk about how well they dissolve in water. Finally, we'll tell you about some of the ways people use group 2 compounds. These compounds are very important, so keep reading!
Group 2 elements also known as the 'alkaline earth metals' are a part of the s-block on the periodic table, having two electrons in the outermost shell. When the metal atoms react to form ions, they lose the two outer electrons and form 2+ ions.
Group 2 elements have two electrons in their outer shell in the outer s-orbital. When they react, they lose these electrons and get a charge of 2+. The melting points of these elements decrease as you go down the group. The first ionisation energy and electronegativity also decrease as you go down the group. This means that group 2 elements become more reactive as you go down the group.
Group 2 compounds are formed when group 2 elements combine with other elements. Calcium hydroxide (Ca(OH)2) is a well-known compound that is made by mixing water and quicklime. Magnesium carbonate (MgCO3) is another example of a group 2 compound. It is a white solid and is found in many minerals. Strontium oxide (SrO) is made when strontium reacts with oxygen. This compound is useful in making ceramics. Check out the 'Group 2' explanation for more information.
The metals magnesium to barium react with water. Beryllium does not react with water.
Magnesium reacts with steam to produce magnesium oxide.
Mg(s) + H2O(g) —› MgO(s) + H2(g)
Magnesium reacts extremely slowly with cold water producing magnesium hydroxide.
Mg(s) + 2H2O(l) —› Mg(OH)2(aq) + H2(g)
The rest of the group 2 metals are able to react with cold water and form metal hydroxides and hydrogen.
Observations:
the metal dissolving and it dissolves faster going down the groupfizzing the solution heating up with calcium, the solution becomes more saturated, and a white precipitate forms.
The oxides of group 2 metals are basic oxides apart from beryllium oxide. They react with water to form metal hydroxides and the solutions are strongly alkaline due to the hydroxide ions (OH-). For example:
CaO(s) + H20(l) —› Ca(OH)2(aq)
The hydroxides of group 2 elements magnesium to barium are soluble in water and form alkaline solutions. The solutions are strongly alkaline due to the presence of the hydroxide ions, OH-. The products of this reaction always has the same formula of M(OH)2, where M is a Group 2 metal.
The carbonates of the group 2 metals are insoluble in water except for BeCO3.
The oxides of group 2 metals react with acids to form salts. An example of this is:
CaO(s) + 2HNO3(aq) —› Ca(NO3)2(aq) + H2O(l)
This equation shows calcium oxide reacting with dilute nitric acid, producing calcium nitrate and water.
When group 2 hydroxides react with dilute acids then the product is a colourless solution of metal salts. An example of this is:
Ca(OH)2(aq) + 2HCl(aq) —› CaCl2(aq) + 2H2O(l)
The group 2 carbonates react with dilute acid to produce a salt, water and carbon dioxide. For example,
The group 2 carbonates decompose when heated to form the oxide and carbon dioxide. An example of this is:
CaCO3(s) —› CaO(s) + CO2(g)
The group 2 hydroxides become more soluble as you go down the group. Due to this, the pH of the solution increases as the concentration of the OH- ions increases.
An equation that represents the hydroxide dissolving in water is:
X(OH)2(aq) —› X2+(aq) + 2OH-(aq)
In this instance, the X represents a group 2 element.
As you go down group 2, the solubility of the sulfates decreases. Magnesium is the most soluble in the group and barium is the least which makes it insoluble.
Let's explore some ways that common group 2 compounds are used.
Magnesium oxide (MgO) is a white solid that can withstand very high temperatures, so it's often used to line furnaces. When MgO is mixed with water, it turns into magnesium hydroxide (Mg(OH)2), which is used in antacids and laxatives because it's insoluble in water. Calcium hydroxide (Ca(OH)₂) is slightly soluble in water, so it's used to make limewater, which can be used in agriculture to adjust soil pH. Calcium oxide (CaO) is used to remove sulfur dioxide (SO2) from flue gases produced when we burn fossil fuels to make electricity. Barium hydroxide (Ba(OH)₂) can be used in chemical analysis as an alkali. Barium sulfate (BaSO4) is insoluble and is used in medical tests to diagnose disorders of the intestines and stomach. Acidified barium chloride (BaCl2) is used to test for sulfate ions by adding it to a solution – if there's a white precipitate, then sulfate ions are present.
To summarize, group 2 compounds are formed when group 2 elements combine with other elements. When group 2 metal atoms react, they lose their two outer electrons and form 2+ ions. Beryllium does not react with water, but the rest of the group 2 metals can react with cold water to form metal hydroxides and hydrogen gas. The oxides of group 2 metals react with acids to form salts. The solubility of group 2 hydroxides increases as you go down the group, while the solubility of group 2 sulfates decreases. Barium sulfate (BaSO4) is insoluble and has various medical uses.
What are group 2 compounds?
When the group 2 metals react to form ions, they lose the two outer electrons and form 2+ ions. Elements of group 2 can form compounds when elements are combined together.
What are some uses of Group 2 compounds?
Barium sulfate (BaSO4), which is insoluble, is used in medicine. It absorbs X-rays strongly and is used to diagnose disorders of the intestines and stomach. Due to its insolubility, it is not absorbed into the bloodstream from the gut. Magnesium hydroxide is the active ingredient in milk of magnesia, which is used as an antacid and laxative.
What is the solubility of Group 2 compounds?
- The group 2 hydroxides become more soluble as you go down the group.- The group 2 sulfates become less soluble as you go down the group.
What are some common properties of group 2 compounds?
- The oxides of group 2 metals are basic oxides apart from beryllium oxide.- The oxides of group 2 metals react with water to form metal hydroxides which are strongly alkaline solutions.- The carbonates of the group 2 metals are insoluble in water except for BeCO3.-The oxides of group 2 metals react with acids to form salts.
What are some common reactions of group 2 compounds?
- The oxides of group 2 metals, apart from beryllium oxide, react with water to form metal hydroxides. - The oxides of group 2 metals react with acids to form salts. - Group 2 hydroxides react with dilute acids. The product is a colourless solution of metal salts. - The group 2 carbonates decompose when heated to form the oxide and carbon dioxide.
