Problem 38
Question
Phosgene was used as a chemical weapon during World War I. Despite the name, phosgene molecules contain no atoms of phosphorus. Instead, they contain atoms of carbon and the group 16 element in the second row of the periodic table and the group 17 element in the third row. What are the identities and atomic numbers of the two elements?
Step-by-Step Solution
Verified Answer
Answer: The two elements in a phosgene molecule are oxygen (O) and chlorine (Cl). Their atomic numbers are 8 and 17, respectively.
1Step 1: Locating Elements in the Periodic Table
To identify the two elements mentioned in the problem, we need to look at the information given: the second row of the periodic table and the group 16 element, and the third row of the periodic table and the group 17 element.
2Step 2: Identify the Group 16 Element
In the periodic table, the group 16 elements are the chalcogens. The second row of the periodic table includes elements 3 to 10, in which the group 16 element is oxygen (O). So the first element in the phosgene molecule is oxygen.
3Step 3: Identify the Group 17 Element
The group 17 elements in the periodic table are the halogens. The third row of the periodic table includes elements 11 to 18, in which the group 17 element is chlorine (Cl). So the second element in the phosgene molecule is chlorine.
4Step 4: Determine the Atomic Numbers of the Elements
To find the atomic numbers of the identified elements, refer to the periodic table. The atomic number is the number of protons in the nucleus of an atom of that element. Oxygen has an atomic number of 8, and chlorine has an atomic number of 17.
5Step 5: Final Answer
The identities of the two elements in a phosgene molecule are oxygen (O) and chlorine (Cl). The atomic numbers of these elements are 8 and 17, respectively.
Key Concepts
Group 16 ElementsGroup 17 ElementsAtomic Number
Group 16 Elements
Group 16 elements are known as chalcogens and occupy the 16th column of the periodic table. These elements include oxygen, sulfur, selenium, tellurium, polonium, and the synthetic element livermorium. Each of these elements shares similar chemical properties due to having the same number of valence electrons, which is crucial for forming compounds.
Chalcogens have six valence electrons, meaning they often form compounds by gaining or sharing two additional electrons to achieve a full outer shell. The term "chalcogen" is derived from a Greek word meaning "ore former," and indeed, many of these elements are found in mineral ores.
Chalcogens have six valence electrons, meaning they often form compounds by gaining or sharing two additional electrons to achieve a full outer shell. The term "chalcogen" is derived from a Greek word meaning "ore former," and indeed, many of these elements are found in mineral ores.
- Oxygen (O): The most significant and abundant chalcogen. It is colourless and odourless, essential for combustion and respiration.
- Sulfur (S): Known for its distinctive yellow color and distinctive smell, used historically in gunpowder and modern-day in fertilizers.
Group 17 Elements
Group 17 of the periodic table features the halogens, a group of elements known for their vigorous reactivity. The halogen series includes fluorine, chlorine, bromine, iodine, and astatine. All halogens have seven valence electrons, compelling them to seek one extra electron to complete their outer shell, which makes them highly reactive, especially with alkali metals and alkaline earth metals.
In their natural state, halogens vary in physical states: fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids. Their diversity demonstrates how changes in atomic structure can influence physical properties.
In their natural state, halogens vary in physical states: fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids. Their diversity demonstrates how changes in atomic structure can influence physical properties.
- Chlorine (Cl): It's a greenish-yellow gas at room temperature. Used widely in water purification and bleach products.
- Fluorine (F): The most electronegative element, which makes it highly reactive and essential in dental care products.
Atomic Number
The atomic number is a fundamental characteristic of every chemical element, representing the number of protons in an element's nucleus. This number distinguishes each element from all others and is unique to every element. For instance, hydrogen has an atomic number of 1, which means it has one proton, while carbon has an atomic number of 6, signifying six protons.
The concept of atomic number is critical because:
The concept of atomic number is critical because:
- It defines the element's identity: No two different elements can have the same atomic number.
- Dictates the element's properties and place in the periodic table: Elements are organized in ascending order of their atomic numbers.
- Influences the chemical behavior: The number of protons affects the element's ability to bond and interact with other elements.
Other exercises in this chapter
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