In the early 1960s, krypton was found to react with fluorine gas in an electrical discharge tube at -183 °C. The compound formed was KrF2. What are the oxidation states of Kr and F in this compound? What is the electron-dot structure and geometry?

Name: Chemistry
Author: McMurry
ISBN: 9781292336145

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Step 1: Determine the oxidation states of Kr and F in KrF_2. Start by knowing that fluorine (F) is more electronegative and typically has an oxidation state of -1.

Step 2: Since there are two fluorine atoms, the total oxidation state contributed by fluorine is 2(-1) = -2.

Step 3: The compound KrF_2 is neutral, so the sum of the oxidation states must be zero. Therefore, the oxidation state of Kr must be +2 to balance the -2 from the fluorine atoms.

Step 4: Draw the electron-dot structure for KrF_2. Krypton (Kr) is a noble gas with a full valence shell, but in KrF_2, it forms bonds with two fluorine atoms. Each fluorine atom shares one pair of electrons with krypton.

Step 5: Determine the geometry of KrF_2. With two bonding pairs and no lone pairs on the central atom (Kr), the geometry is linear according to VSEPR theory.

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Oxidation States

Oxidation states indicate the degree of oxidation of an atom in a compound, reflecting the number of electrons lost or gained. In KrF2, fluorine typically has an oxidation state of -1, as it is more electronegative. To find the oxidation state of krypton (Kr), we set up the equation: x + 2(-1) = 0, leading to x = +2 for Kr.

Electron-Dot Structure

The electron-dot structure, or Lewis structure, represents the valence electrons of atoms within a molecule. For KrF2, the structure shows krypton at the center with two fluorine atoms bonded to it, each contributing three lone pairs of electrons. This visualization helps in understanding bonding and electron distribution in the compound.

Molecular Geometry

Molecular geometry describes the three-dimensional arrangement of atoms in a molecule. For KrF2, the geometry is determined by the VSEPR theory, which predicts a linear shape due to the two bonding pairs and three lone pairs on krypton. This arrangement minimizes electron pair repulsion, resulting in a specific spatial configuration.