The polarity of CH3NH2

The above photo is a 3-D model of the molecule methylamine, also known as CH3NH2. Carbon is the central atom, which is represented by the black sphere, the nitrogen represented by the blue sphere, and the five hydrogen atoms are represented by the white spheres. CH3NH2 is a Carbon has an electronegativity value  of 2.5, nitrogen's electronegativity value is 3.0 and hydrogen has an electronegativity value of 2.2. Because the natural flow of polarity goes from the atom with the smallest electronegativity value to the greatest, polarity flows from hydrogen (that's bonded to the nitrogen) to the nitrogen, hydrogen (that's bonded to the carbon) to the carbon, and carbon to the nitrogen.

The charge of this molecule is not evenly distributed, and the unshared electron pairs make the molecule even more negative, which just increases how uneven this molecule is. CH3NH2 has two oppositely charged ends, and bonds between hydrogen and nitrogen, which makes it a polar molecule.

The easiest way to tell if a molecule is polar or nonpolar is to make a Lewis or dash structure which is shown above. One easy way to tell if it's polar is if the central atom has unpaired electrons, which it does in this case. Another way to tell polarity is if there is a bond between hydrogen and either nitrogen (in this case), oxygen, or flourine. If neither of those apply, then you need to look at the electronegativity charges to find out.