Previous days ago my friends and I (in a group of 4) had finished a You Tube video explaining interactions between H₂O molecules and salt (NaCl) when dissolved in water. If you are interested, the video is available above and feel free to watch it.

The post-activity of this task is to do a self-reflection about the video, discussing about the bonds within the water molecules and hydrogen bond interactions with other molecules like salt (NaCl). The good thing about this task is self-learning. Via self-learning, I can do extra reading, understand deeper about the topic and most importantly, felt satisfied of my own effort (even though it is a pretty simple interaction). Below is roughly what I understand about how salt is dissolved in water.

Basically, water is a polar molecule because of the uneven charge distribution. Since that oxygen is more electronegative than hydrogen, so oxygen atom is partially negative and hydrogen atom is partially positive. Sodium chloride or generally known as table salt is an ionic compound consist of sodium ion (an anion or a positively charged ion) and chloride ion (a cation or a negatively charged ion). When salt is dissolved in water, dissociation of salt occurs and water molecules are responsible for it. The partially negative side of the water is attracted to the chloride ion. Same things goes to sodium ion where the partially positive side of the water is attracted to sodium ion. The molecular-ion attraction on both side break the ionic bond of sodium chloride and pull the anion and cation apart. At this point, dissociation occur or in other term salt is dissolved in water.

If you ever thought of why not water molecules is pulled apart instead of salt, it is because water molecules has covalent bond. In a covalent bond, the electrons are shared between atoms. As oxygen is more electronegative than hydrogen atom, it attract electrons stronger compare to hydrogen. The unequal sharing of electrons result in polarity of water molecule. The fact that covalent bond is much stronger than ionic bond let salt dissociate instead.

Lastly, hydrogen bond is an interaction between a covalently bonded hydrogen atom in a donor group and a pair of non-covalent electrons on an acceptor group. The ability of a group to act as a hydrogen bond donor depends on its electronegativity. Generally, only Oxygen, Nitrogen and Fluorine atom have sufficient electronegativity to act as hydrogen bond donor. Besides, a hydrogen bond acceptor must possess a lone pair for the formation of a hydrogen bond. Water able to form hydrogen bonding within themselves because of the presence of oxygen atom. Sodium and chloride ion does not form hydrogen bond with water molecules because of lacking in electronegativity. They are bound to water by electrostatic force as water is a polar molecules.