’17 X This is a Lewis dot diagram: Which element is represented? phosphorus (P) chlorine (CI) boron (B) sulfur (S) Which two elements have the same number of valence electron 18 19 The diagram represents a neutral atom 0f fluorine-19′
The Correct Answer and Explanation is:
Correct Answers:
- The element represented in the Lewis dot diagram with 7 valence electrons is:
Chlorine (Cl) - Two elements that have the same number of valence electrons as chlorine are:
Fluorine (F) and Bromine (Br) - The diagram represents a neutral atom of fluorine-19.
Explanation
A Lewis dot diagram is a simplified representation of the valence electrons (outermost electrons) of an atom. Each dot around the chemical symbol represents one valence electron. The number of valence electrons determines how an element reacts chemically with others.
In the first question, we are told the element’s Lewis dot diagram shows seven dots, which means it has seven valence electrons. To determine the element, we look at the periodic table. Elements in Group 17 (also known as Group VIIA) of the periodic table each have seven valence electrons. These elements are known as halogens and include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).
Given the choices:
- Phosphorus (P) has 5 valence electrons (Group 15)
- Chlorine (Cl) has 7 valence electrons (Group 17)
- Boron (B) has 3 valence electrons (Group 13)
- Sulfur (S) has 6 valence electrons (Group 16)
So the correct answer is chlorine (Cl).
In the second part, the question asks which two elements have the same number of valence electrons as chlorine. We know chlorine has seven. Other elements with seven valence electrons are fluorine and bromine. These are in the same group as chlorine and exhibit similar chemical behavior.
Lastly, fluorine-19 refers to a neutral atom of fluorine with a mass number of 19. Since the atomic number of fluorine is 9, it has 9 protons. In a neutral atom, it also has 9 electrons. The mass number 19 indicates it also has 10 neutrons (19 minus 9). This confirms the identity of the atom in the diagram.
