Answer:
Non-polar
Step-by-step explanation:
To determine if BCl3 is polar or non-polar, we need to look at its Lewis structure and then check the symmetry of the molecule. Also, we check the net dipole moment.
Boron has an atomic number of 5, so has an electronic structure of 2,3. It has 3 electrons on its outer shell or in other words 3 valence electrons which participate in the bonding with Chlorine.
Chlorine has 7 electrons on its outer shell
In BCl3, Boron shares an electron with each Chlorine atom, forming 3 covalent bonds of B-Cl. All of the 3 valence electrons are involved in the formation of bonds with Cl3, so there are no lone pairs. 3 bond pairs form a trigonal planar structure with bond angles of 120 degrees.
Looking at the Lewis structure, we have Boron in the centre and three Chlorine atoms that surround the Boron. Each electron pairs around Boron form an equalateral triangle to minimise repulsion and maximise distances around the bonding pairs. Although the B-Cl bond in BCl3 is polar, they cancel each other out as it is symmetrical. The polar bonds point in opposite directions as Chlorine is more electronegative, which causes the cancelling out of polar bonds - resulting in a net dipole moment of 0.
No poles are formed - BCl3 is non-polar.