Explain the statement not every molecule with polar bonds is polar. use ccl4 as an example?

Polarity is induced in the molecules when there are significant electronegativity differences between its atoms. Due to this difference of electronegativity, one atoms pulls shared electrons more towards itself and gets partial negative charge while the other atoms that has less electronegativity gets a partial positive charge.This electronegativity difference creates poles and a dipole moment in the whole molecule. The example of such a polar molecule is H2O.

However, sometimes the molecule is composed of atoms that have substantial electronegativity differences but still the molecule is not polar.

Why ?

Because the polar bonds are organized in a symmetrical way, in a way that the dipole moment of whole molecule becomes zero. This is because bond polarity is cancelled because of a symmetrical shape.

Take the example of carbon tetrachloride or CCL4. No doubt, chlorine and carbon have electronegativity difference and the molecule should be polar, but in actual it is not polar. If you look at the structure of CCl4 in attached figure, you can see that you can see that the shape of molecule is symmetrical. There is one bond on right and left each side of carbon , which cancel the net polarity of each other. One bond is on top and bottom of carbon each, that cancel the dipole moment of each other. Though electronegativity difference still exists but the overall molecule is non-polar. However, when the molecule reacts with some other atom or molecule and replaces chlorine atoms, the symmetry is broken and the resultant molecule becomes polar.

Hope it helps! :)

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.