Chem context
____s are the subatomic particles involved in creating chemical bonds between atoms.
Electron(s)
(specifically valence electrons in outermost shell)
_____, ______,______, and ______ make up 96% of living matter
Carbon, Hydrogen, Oxygen, and Nitrogen
____ action allows water to reach plant leaves from the roots. ______ and _____, two properities of water, play a role in this action.
_Capillary_;_Adhesion_;Cohesion
_pH_;_Hydrogen_;_acidic;_basic
πΎπππ'π ππππ ππππ ?
This bond is made when atoms share electrons in order to fill their valence shell.
Covalent bond!
πΎπππ'π ππππ ππππ ?
It breaks and reforms constantly between water molecules, it technically is not a chemical bond, and it is formed between a partially positive hydrogen in one polar covalent molecule and an electronegative atom of another polar covalent molecule.
πΎπππ'π ππππ π·πππππππ?
Due to water's ability to form hydrogen bonds, molecules of water "stick" together more often and water is more structured than most liquids.
-Increased cohesion
πΎπππ'π ππππ π·πππππππ?
In water, heat energy is first absorbed by the hydrogen bonds present (absorbed heat breaks H-bonds). This makes water resist temperature change, since a relatively large amount of heat energy is needed for 1 g of water to go up 1β
High Specific Heat
π¬ππππππ
Why are some covalent bonds polar, and some are nonpolar?
-Polar covalent bonds form when electrons are unequally shared, one element is more electronegative than the other, causing a partial negative charge on that side of the molecule, and a partial positive charge on the other.
Ex: Water! Oxygen is more electronegative, electrons spend more time near it, it has the partial (-) charge, hydrogens have the partial (+) charge
-Nonpolar bonds describe equal sharing of electrons; atoms involved are similar in electronegativity. No partial charges on these molecules.
π¬ππππππ
Why is atomic structure important when you start discussing things like water properties and how macromolecules function?
-Atomic structure determines how atoms bond and what kind of bonds are made. The type of bonds that make a molecule affect how it behaves with other molecules.
(Ex. because of Oxygen's and Hydrogens' sturctures in water, H2O is a polar molecule with properites like increased cohesion and adhesion!)
π¬ππππππ
Why ice floats on water and why this is important to life on Earth.
-Ice is less dense than liquid water. This is because, as water freezes, the molecules do not move enough to break hydrogen bonds. The molecules, with the hydrogen bonds between them, form a crystalline structure where the molecules are more spread out than in liquid form.
-Floating ice provides insulation to the water and organisms below it, allowing for acceptable living conditions
π¬ππππππ
Water's ability to moderate temperature.
-High specfifc heat: allows bodies of water to absorb heat during hot days, moderating the temperature of the surrounding climate
-High heat of vaporization: Evaporative cooling: When water evaporates into gas form, heat is released and there is a cooling effect. When this happens in organisms such as humans, overheating is prevented.
What kind of bond is made between a cation of sodium and an anion of chlorine?
Ionic bond
πΎπππ ππ ππππ πππππππ ππ πππππππ ππ?
Iodine is an element necessary for humans in small quantities, this element is needed for the production of thyroid hormones.
Trace element.
A Water Strider is an insect capable of walking on water. Which property of water allows for this?
-Water's increased surface tension due to increased hydrogen bonding/ cohesion at the surface of water
Water molecules are able to interact with NaCl, dissolving it into cations and anions. This showcases how water is a great solvent for many solutes.
What kind of solutes can water dissolve and why?
-Can generally dissolve most Hydrophilic/ionic/polar solutes
-Water is polar and can form Hydrogen bonds, so it is able to have attractions with the previously mentioned solutes. ("Like dissolves like")
Describe the shape of a water molecule as a result of atom structure and bonding.
-Water is a polar covalent molecule made up of one Oxygen atom and two Hydrogen atoms. Oxygen is more electronegative than Hydrogen, so it "pulls" on the shared electrons. The electrons spend more time near the Oxygen, so that region of the molecule becomes partially negative, while the hydrogen side becomes partially positive. The polar bonds result in H2O having a " V " shape.
If a Carbon molecule was to covalently bond with four Hydrogens, would the molecule be polar or nonpolar?
(Carbon and Hydrogen are roughly equal in electronegativity)
Bonus: Are hydrocarbons polar or not?
-Nonpolar
-Hydrocarbons are generally nonpolar
Predict what would happen to the water in a plant if a thin coating of nonpolar oil were applied to the leaves.
Explain your reasoning for the previous question.
-Fewer water molecules would be able to evaporate from the leaves
-Water is a polar molecule; it can interact with other polar or ionic molecules. Water molecules would have trouble crossing through a nonpolar oil since the oil is hydrophobic and would not interact with the water molecules
A betta fish releases CO2, as a product of cellular respiration, in a water tank. CO2 then dissolves in water forming Carbonic Acid. Carbonic Acid dissociates, releasing Hydrogen ions into the water tank.
Predict what will happen to the pH.
Provide reasoning for your prediction.
-The pH will decrease
-When Carbonic Acid dissociates and releases Hydrogen ions into the fish tank, the concentration of H+ increases. The more H+, the more acidic the environement and the lower the pH.