Answer the questions in the table below about the shape of the chlorine pentafluoride (ClF5) molecule. How many electron groups are around the central chlorine atom? Note: Electron groups can be lone pairs, single bonds, double bonds, or triple bonds. What phrase best describes the arrangement of these electron groups around the central chlorine atom? (You may need to use the scrollbar to see all the choices.) (Choose one)
The Correct Answer and Explanation is:
To determine the electron groups around the central chlorine atom in chlorine pentafluoride (ClF5), we need to analyze the bonding and lone pairs of electrons.
Step 1: Determine the structure of ClF5
Chlorine pentafluoride (ClF5) consists of a central chlorine atom bonded to five fluorine atoms. This structure is described as follows:
Chlorine (Cl) is the central atom.
Each of the five fluorine atoms is bonded to chlorine via a single bond.
In addition to these bonding pairs, chlorine has lone pairs of electrons. To figure out how many, we’ll use the electron configuration and total valence electrons.
Step 2: Count the total number of valence electrons
Chlorine (Cl) is in Group 17 of the periodic table, so it has 7 valence electrons.
Each fluorine (F) atom, also in Group 17, has 7 valence electrons, and since there are five fluorine atoms, the total number of valence electrons contributed by fluorine is 5 × 7 = 35 electrons.
Thus, the total number of valence electrons in ClF5 is:
Chlorine: 7 electrons
Fluorine: 35 electrons
Total: 7 + 35 = 42 valence electrons.
Step 3: Distribute the electrons
Each Cl-F bond requires 2 electrons, and since there are 5 fluorine atoms, 5 bonds will use up 10 electrons. This leaves us with 42 – 10 = 32 electrons to be distributed as lone pairs.
The chlorine atom has more than 8 valence electrons (which is common for atoms in period 3 and beyond), so it can accommodate more than 4 bonds or lone pairs. After placing the bonding electrons, we distribute the remaining electrons as lone pairs. Chlorine in this case has 2 lone pairs, as the molecule has 5 bonding pairs and 2 lone pairs, making a total of 7 electron groups around the central chlorine atom.
Step 4: Electron group arrangement
The electron group arrangement around chlorine is described by the octahedral geometry. In an octahedral arrangement, there are 6 positions where electron groups can be placed. However, in ClF5, only 5 fluorine atoms are bonded to chlorine, and 2 positions are occupied by lone pairs of electrons.
Conclusion
The central chlorine atom in ClF5 has 7 electron groups around it, consisting of 5 bonding pairs and 2 lone pairs. The best description for the arrangement of these electron groups is octahedral. The lone pairs do not affect the bond angles significantly but are considered in the overall electron group count.
Thus, the answers are:
Number of electron groups: 7
Arrangement of electron groups: Octahedral
