Each Be–Cl bond is polar because the two atoms have different electronegativities. The number of outer atoms (2) and lone pairs on the central atom (0) indicate that this molecule has a linear geometry. The bonds in a linear molecule are symmetric, and so their dipoles cancel out.
Each O–H bond is polar because the two atoms have different electronegativities. The number of outer atoms (2) and lone pairs on the central atom (2) indicate that this molecule has a bent geometry. The bonds in a bent molecule are asymmetric, and so their dipoles do not cancel out. In addition, the asymmetric arrangement of the lone pairs on O further contribute to the dipole of this molecule.
An O–O or O=O bond is nonpolar because the two atoms have the same electronegativity. Because there is no overall polarity in O2, the molecule is nonpolar.
Chlorine is more reactive than argon, because argon is not reactive at all. Chlorine only has to gain 1 valence electron
The opposite type of reaction (where energy is taken in from the surroundings of a reaction and thus the energy of the reactants is lower than that of the products) is called an endothermic reaction
By dividing mass with volume, you will end up with density
