Chromium atomic number
The atomic number of chromium is 24.
Electron configuration
The electron configuration of chromium is 1s2 2s2 2p6 3s2 3p6 4s1 3d5.
Electron configuration for cr3+
The electron configuration for Cr3+ is 1s2 2s2 2p6 3s2 3p6 3d3.
Geometry
The geometry of chromium depends on the compound or molecule it is present in.
In its most common oxidation state (+3), such as in CrCl3 or Cr(OH)3, chromium adopts an octahedral geometry. This means that it is surrounded by six ligands or atoms, arranged at the corners of an octahedron.
However, chromium can also exist in other oxidation states and geometries. For example, in its +6 oxidation state, it can adopt an octahedral geometry in compounds like CrO3. In its +2 oxidation state, it can adopt a tetrahedral or distorted octahedral geometry, depending on the compound.
Magnetic properties of Cr 3+
In valence bond theory
In valence bond theory, the magnetic properties of Cr3+ can be explained by considering its electronic configuration. Cr3+ has three unpaired electrons in its d-orbital (3d3).
According to Hund's rule, these unpaired electrons will occupy different orbitals with parallel spins to minimize electron-electron repulsion. This results in a high-spin configuration, where the total spin (S) is maximum.
In the case of Cr3+, the high-spin configuration is designated as 3d3, with S = 3/2. This means that the three unpaired electrons have parallel spins, leading to a net magnetic moment.
Therefore, in valence bond theory, Cr3+ is considered paramagnetic, meaning it is attracted to an external magnetic field due to the presence of unpaired electrons.
The atomic number of an element is the number of protons found in the nucleus of an atom of that element. In the case of chromium (Cr), the atomic number is 24.
To find the atomic number of an element, you can refer to the periodic table of elements. The periodic table lists all known elements in order of increasing atomic number. Chromium is located in the transition metals section of the periodic table, specifically in the 4th period and Group 6 (or Group VI-B).
By locating chromium on the periodic table, you can identify its atomic number. In this case, chromium is found between the elements vanadium (atomic number 23) and manganese (atomic number 25), so its atomic number is 24.