September 10th - Biology -Energy, Bonding, Enthalpy, and Entropy Concepts (Lecture Notes)

A set of practice flashcards covering energy concepts, bonding, enthalpy, and entropy from the lecture notes.

What type of energy is stored due to an object's height above sea level?

Potential energy — energy stored by position, which can do work when released.

What energy form is associated with the motion of an object?

Kinetic energy.

How does potential energy of water contribute to electricity generation as it flows to lower levels?

The potential energy of water is converted to kinetic energy and can do work, such as generating electricity.

In atoms, what happens when electrons move to higher energy levels?

Electrons store energy as higher-energy (excited) states and can drop to lower levels, releasing energy.

What is a covalent bond?

A bond formed when two atoms share electrons.

Give examples of covalent bonds mentioned in the notes.

C–C, C–H, and C–O bonds.

How is bond polarity determined?

By the difference in electronegativity between the two bonded atoms.

What are the electronegativities of carbon and hydrogen in the notes, and what is their difference?

Carbon ≈ 2.55, Hydrogen ≈ 2.20; difference ≈ 0.35, making the C–H bond slightly polar toward carbon.

According to the notes, what is the relationship between nonpolar bonds and stored energy?

The notes state that more nonpolar character in a bond is associated with more energy stored in that bond.

Why is gasoline considered high-energy in the notes?

Because organisms lack the biological machinery to readily break down gasoline for energy, unlike glucose which can be metabolized.

What is enthalpy in the context of the notes?

The sum of a system’s potential and kinetic energy (the energy content of the molecule).

What does ΔH represent?

Change in enthalpy, ΔH = H(products) − H(reactants).

What does a negative ΔH indicate in a reaction?

Exothermic reaction — energy (heat) is released.

What does a positive ΔH indicate in a reaction?

Endothermic reaction — energy (heat) is absorbed.

What is isomerization?

A structural change in a molecule that alters its arrangement without changing its molecular formula.

What is entropy?

A measure of energy dispersion/disorder in a system, related to the number of accessible microstates.

What biological example is given to illustrate a change in enthalpy (glucose phosphorylation)?

Glucose gains a phosphate from ATP to form glucose-6-phosphate; ΔH is negative (energy released) in this step.