Water Polarity The Universal Solvent

The story of Oxygen and two Hydrogens

Word to know Atoms: Solvent: Protons: Solute: Neutrons: Solution: Electrons: Polar: Energy shells/levels: Nonpolar: Valance electrons: Covalent bonds:

The Start Atoms: the basic building blocks of ordinary matter 3 sub-particles: neutrons, protons, and electrons. Neutron: holds the protons together, has a neutral charge, and is found in the nucleus. Proton: found in the nucleus, identifies an atom, and has a positive charge. Electron: has a negative charge, determines the behavior of the atom, and is found on the outside of the atom in energy levels or shells. Draw a picture of an oxygen atom and two hydrogen atoms. Then name them for our story.

Energy levels or shells Energy levels or shells hold the electrons 1st level can hold 2 electrons 2nd level can hold 8 electrons 3rd level can hold 18 To make the atom happy the outer shell or energy level needs to have 2 electrons if it is the 1st energy level and 8 electrons for any higher level. Valance electrons are the electrons found in the outer shell and are the ones which are either shared or given away during bonding. Do our three atoms have full outer shells? Draw our atoms and show whether they are happy (full outer shells) or sad (no full outer shells).

The Meeting Oxygen is a sad atom and would like two more electrons in its outer shell. The hydrogen atoms are also sad because they don’t have full shells. How could all the atoms be happy? Share their electrons This sharing is called covalent bonding. When Oxygen and Hydrogen share electrons they form what? Water. Draw the formation of water.

Why is Water Polar? Oxygen has more protons than hydrogen; because of this, the electrons will spend more time around the oxygen atom than around the hydrogen atoms. Oxygen will then have a negative charge, while the hydrogen atoms will have positive charges. Draw the electrons spending more time with the oxygen atom. Next draw on the water molecule where it is positive and where it is negative. Polarity means a molecule has a positive and a negative side. There are some molecules that are nonpolar and don’t mix with polar atoms. For example, oil is nonpolar and will not mix with polar water.

The Coolness of Polarity Because water is polar it can do several interesting things. Cohesion: Water sticking/attracted to itself Draw a picture of water sticking to itself Adhesion: water attracted to other substances Draw a picture of water sticking to other substances So why is polarity so cool? https://www.youtube.com/watch?v=o8TssbmY-GM Surface tension: rain drops, bugs walking on water, etc.. Capillary action: why paper towels soak up water, plants live, fountain pens draw up ink The universal solvent…

The Universal Solvent: Water Because water is polar it likes to dissolve other polar items. It is actually one of the best solvents out there. What is a solvent? the dissolver. Can be liquid, gas, or solid. Gas can dissolve gas, liquid can dissolve all 3 states. The solvent can be polar or non polar. There is even a name for the substance being dissolved… Solute Now when you mix the two together you get a solution. List a good thing that comes from water dissolving a solute. List a bad thing that comes from water dissolving a solute.