You wish to measure the iron content of the well water on the new property you are about to buy. you prepare a reference standard solution with a concentration of you treat of this reference with and excess to form a red complex and dilute the reference to the diluted reference is placed in a cell with a 1.00‑cm light path. you then take of the well water, treat with and excess and dilute to this diluted sample is placed in a variable pathlength cell. the absorbance of the reference and the sample solutions match when the pathlength is what is the concentration of iron in the well water? for each solution, the zero is set with a blank.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

intermolecular forces are the forces between molecules or particles.

there are two kinds of van der waals forces: weak london dispersion forces and stronger dipole-dipole forces.

in molecule of water there are dipole-dipole forces between negatively charged oxygen from one molecule of water and positively charger hydrogen of another molecule of water.

hydrogen bond is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (h), covalently bound to a highly electronegative atom such as flourine (f), oxygen (o) and nitrogen (n) atoms.