A. In a polar molecule, the bond is polar covalent. That is, the electrons are shared but are slightly more attracted to the more electronegative atom. That part of the molecule has a negative partial charge density, and the other has a positive partial charge density (there is no symmetry in the distribution of the electricity density)
B. Charges are not affected, the molecule is neutral because electrons are shared. A molecule has the same number of electrons and protons which balance the charges in a molecule. Since all atoms are electrically neutral, then when they combine the form of a neutral molecule.
Explanation:
To determine polarity, the geometry of the molecule must be taken into account to determine the distribution of atoms and their electronegativity (tendency to attract electrons) to determine to which points of the molecule the electrons will be most attracted.
Atoms can share electrons to form chemical bonds and thus form different compounds. In the case of non-polar molecules, when formed in a covalent bond (two atoms bond by sharing valence electrons reaching "stable octet") between equal atoms, the molecule is neutral since it has zero electric charge. In this type of bond there is no change in the oxidation number of the atoms because their shared electrons are equidistant. Covalent bonds in which the electrons are shared equally are called non-polar covalent bonds. This is because the atoms are just the same, they have the same electronegativity, so they "attract" the electrons with the same force and the electrons surround the atoms equally. The charge density distribution is the same for both, there is asymmetry in the distribution of it.
Polar molecules are formed when bonds are formed by different atoms with large differences in electronegativity. The molecule is electrically neutral as a whole because it has an equal number of positive and negative particles, but there is no symmetry in the distribution of the electricity density. A polar bond is one in which a pair of electrons is more attracted to one of the atoms. This causes one end of the molecule to acquire a positive partial charge density and the other end of the molecule to acquire a positive partial charge density and the other end of the molecule to acquire a negative partial charge.
So, as a summary:
A. In a polar molecule, the bond is polar covalent. That is, the electrons are shared but are slightly more attracted to the more electronegative atom. That part of the molecule has a negative partial charge density, and the other has a positive partial charge density (there is no symmetry in the distribution of the electricity density)
B. Charges are not affected, the molecule is neutral because electrons are shared. A molecule has the same number of electrons and protons which balance the charges in a molecule. Since all atoms are electrically neutral, then when they combine the form of a neutral molecule. Only ions do not have a neutral electrical charge because of the process of gaining or losing electrons. An ion with a positive electrical charge is called a cation, and an ion with a negative electrical charge is called an anion.
