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31 maj 2016 · If the \(z\)-axis lies in the plane of the molecule: The \(x\)-axis stands perpendicular to the plane; For non-planar molecules, once the z-axis has been defined, the x-axis is the usually chosen so that the xz plane contains as many atoms as possible.
Molecular symmetry is a fundamental concept in chemistry, as it can be used to predict or explain many of a molecule's chemical properties, such as whether or not it has a dipole moment, as well as its allowed spectroscopic transitions. To do this it is necessary to use group theory.
If an object has several axes with different order n, then the one with the highest order is called the principal axis. If there is more than one axis of the same order, then they get distinguished by primes if they are not conjugate.
A note on axis definitions: Conventionally, when imposing a set of Cartesian axes on a molecule, the z axis lies along the principal axis of the molecule, the x axis lies in the plane of the molecule (or in a plane containing the largest number of atoms if the molecule is non-planar), and the y axis makes up a right handed axis system. 3.
x. y. The origin, (0, 0, 0) is the centre of inversion. If the coordinates of every point are changed from (x,y,z) to (-x, -y, -z), and the resulting arrangement is indistinguishable from original - the INVERSION is a symmetry operation, and the molecule possesses a CENTRE OF.
For planar molecules, if the z axis as defined above is perpendicular to the molecular plane, the x axis lies in the plane of the molecule and passes through the greatest number of atoms. If the z axis lies in the plane of the molecule, then the x axis stands perpendicular to the plane.
The independent variable should be plotted on the x-axis. The dependent variable should be plotted on the y-axis. The graph of mass vs. volume places volume on the x-axis and the mass on the y-axis.
