Ch 2

Why is carbon so important in biology?

- It forms up to four covalent bonds.

Why is water capable of forming hydrogen bonds?

- It is highly polar. -The oxygen atom carries a partial negative charge.( because it is more electronegative than hydrogen) -The hydrogen atoms carry partial positive charges.

reaction that is most spontanous.

- a reaction that is slightly exothermic and leads to a huge increase in entropy

chemical reactions involve:

-H (enthalpy) = the total amount of potential energy stored in the chemical bonds of a molecule. --S (entropy) = the amount of disorder. -G (free energy) = the energy available to do work (break and reform chemical bonds).

spontaneous/ exergonic/ catabolic reaction (energy releasing) occur when:

-Occur when the potential energy of the Products is less than the potential energy of the Reactants. ∆G = ∆H - T∆S < 0 = (-) - (+)

non-spontaneous / endergonic / anabolic reactions ( energy absorbing) occur when:

-Occur when the potential energy of the Reactants is less than the potential energy of the Products. ∆G = ∆H - T∆S > 0 = (+) - (-)

why do ionic molecules dissolve and dissociate in water?

-Oxygen and hydrogen differ highly in the degree of electronegativity and therefore form polar covalent bonds. Ionic and polar substances would be insoluble in a nonpolar covalently bonded solvent.

chemical evolution refers to :

-Small molecules reacted to form larger, more complex molecules.

Water exhibits several different properties due to its ability to form hydrogen bonds, including adhesion, cohesion, and surface tension.

-adhesion:the hydrogen bonding between water and another type of molecule, such as the molecules composing the side of a water glass or beaker. -Cohesionon: the attraction between like molecules. Water forms drops on a table. -Surface tension: the resistance of the surface of a liquid to stretching or breaking.

When one of the atoms involved in a covalent bond has a much higher electronegativity than the other atom, what type of bond results?

a polar non covalent bond.

a molecule that cannot form hydrogen bonds with water is:

hydrophoic.

what type of bond has the highest potential energy?

non polar covalent.

most biological organisms function in a pH range of:

pH of 6-8 .

entropy increases when a reaction is:

spontaneous and exothermic.