In physics, inertia refers to the resistance an object displays to a change in its state of motion. The calculation of inertia varies greatly depending on the object and its particular motion. For example, a rotating object such as a spinning top displays a property called a moment of inertia. Smaller objects, such as atoms and molecules, also display this moment of inertia as they rotate. Diatomic molecules, which consist of two atoms, are some of the most commonly studied molecules with regard to rotational inertia. Calculating the rotational inertia of these molecules depends upon two properties --- bond length and mass.
- Periodic table of elements
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Instructions
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1
Identify the mass of each atom of the diatomic molecule. You can find the masses of the atoms in the periodic table, in atomic mass units (amu) under the symbol for each respective element.
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2
Find the bond length for each atom in the diatomic molecule. This is the atom's distance from the molecule's center of mass, the point or axis about which the molecule rotates.
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Plug these values into the inertia formula. The inertia of a rotating molecule is the sum of the products of the mass and the square of the bond length of each respective element.
Moment of Inertia = M1*R1^2 + M2*R2^2, where M and R are the mass and bond length of the atoms in the diatomic molecule.