Question

Match each item on the left with its corresponding group on the right. $$ \begin{array}{ll}{\text { a. alkali metals }} & {\text { 1. group } 18} \\\ {\text { b. halogens }} & {\text { 2. group } 1}\end{array} $$ $$ \begin{array}{ll}{\text { c. alkaline earth metals }} & {\text { 3. group } 2} \\\ {\text { d. noble gases }} & {\text { 4. group } 17}\end{array} $$

Short answer

The correctly matched element groups and their group numbers are as follows: \(a. \text{ alkali metals } = 2. \text{ group } 1 \\ b. \text{ halogens } = 4. \text{ group } 17 \\ c. \text{ alkaline earth metals } = 3. \text{ group } 2 \\ d. \text{ noble gases } = 1. \text{ group } 18 \\ \)

Step-by-step solution

Identify the element group for alkali metals

The alkali metals are a group of elements in the periodic table. They consist of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). They are located in group 1 of the periodic table. Therefore, the correct match for item a is: a. alkali metals = 2. group 1

Identify the element group for halogens

The halogens are a group of elements in the periodic table that include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). They are located in group 17 of the periodic table. Therefore, the correct match for item b is: b. halogens = 4. group 17

Identify the element group for alkaline earth metals

The alkaline earth metals are a group of elements in the periodic table that include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). They are located in group 2 of the periodic table. Therefore, the correct match for item c is: c. alkaline earth metals = 3. group 2

Identify the element group for noble gases

The noble gases are a group of elements in the periodic table that include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). They are located in group 18 of the periodic table. Therefore, the correct match for item d is: d. noble gases = 1. group 18

Summary

The correctly matched element groups and their group numbers are as follows: a. alkali metals = 2. group 1 b. halogens = 4. group 17 c. alkaline earth metals = 3. group 2 d. noble gases = 1. group 18

Key concepts

alkali metals

Alkali metals are a fascinating group of elements found in group 1 of the periodic table. They include elements like lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).
Alkali metals are known for being highly reactive, especially with water, because they have just one electron in their outermost shell. This single electron is easily lost in chemical reactions, allowing them to form positive ions or cations.

Some interesting properties of alkali metals include:

• Softer texture compared to other metals, often soft enough to cut with a knife.
• High reactivity, particularly with water, producing hydrogen gas and a metal hydroxide solution.
• Low melting points relative to most other metals.

Alkali metals play crucial roles in various applications. For instance, sodium is essential in the human body for nerve function, and lithium is used in batteries. These elements are crucial in both chemistry and everyday life.

halogens

Halogens occupy group 17 on the periodic table. This group includes fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).
Halogens are known for their reactivity and are typically found in the form of salts when combined with metals.
The name 'halogen' itself means 'salt-former'.

Key properties of halogens include:

• High electronegativity, meaning they have a strong tendency to attract electrons.
• Exist in various states of matter at room temperature: fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids.
• Typically form diatomic molecules (e.g., \( F_2, Cl_2 \)).

These elements are widely used, such as chlorine for disinfecting water and iodine in iodized salt to prevent deficiencies in humans.

alkaline earth metals

Alkaline earth metals are found in group 2 of the periodic table and include elements like beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).
These metals are named 'alkaline earth' because their oxides were historically called "earths" and are basic (alkaline) when mixed with water.

Notable properties of alkaline earth metals are:

• They have two electrons in their outer shell, making them less reactive than alkali metals, but still quite reactive.
• They are harder and have higher melting points compared to alkali metals.
• Commonly form +2 ions (e.g., \( Ca^{2+} \)).

Alkaline earth metals are vital in various applications. For example, calcium is vital for bones and teeth, and magnesium is used in lightweight metal alloys. Their reactivity and abundance make them useful in industrial processes.

noble gases

Noble gases are a group of elements located in group 18 of the periodic table and include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).
They are characterized by their lack of reactivity, which is why they are termed 'noble'.
This is because they have a full outer electron shell, making them very stable and unlikely to engage in chemical reactions.

Key characteristics of noble gases include:

• Colorless, odorless, and tasteless at room temperature.
• Found in very low concentrations in the atmosphere.
• Capable of producing light when electrically charged, which is the principle behind neon lights.

Noble gases have a range of applications, from helium in balloons due to its low density and non-flammable nature, to argon in light bulbs to prevent the filament from corroding. These elements' unique properties make them indispensable in technology and industry.