Unit Three: Energy and matter

Opener Talk to the people at your table about 2 things you did over break Be ready to share out Turn in your winter break assignment to the box

Agenda Unit Three LTS Free Energy and the Battle Against Entropy I’ll be here after school Thursday

Homework Homework: Videos: “photosynthesis” and “photosynthetic light reactions in detail” Reading: Chapter 10.1-10.3 Essential Question: What are the two parts of photosynthesis? Summarize what happens in each stage. Focus on the inputs and outputs.

Fundamentals Opener. . . Explain the relationship between atoms, molecules and chemical bonds. What is a chemical reaction? What happens to atoms, molecules and chemical bonds during a chemical reaction? What role does energy play in chemical reactions? Discuss with your table group. You have five minutes. Sticks tell us who answers. . .

Unit Three LTs I can describe why all living systems require a constant input of free energy and matter I can explain how photosynthesis provides living things with matter and free energy I can explain how cellular respiration provides living things with a useable source of free energy I can explain why living things must exchange matter with the environment, and describe how these exchanges take place* *: Winter break LT. . .

Scale for Free Energy

Entropy and the Second Law of Thermodynamics Entropy is a measure of how evenly the energy in a system is distributed As energy spreads through a system, the entropy of the system increases The Second Law of Thermodynamics states: Transfers and transformations of energy lead to an increase in entropy Things are not going to just happen- instead of increasing order you have decreasing order in the rest of the universe because life is order. Natural selection from the origins of life has acted upon us to capture energy and defy the 2nd law of thermodynamics. Think- where is this energy coming from? Near vents, lighting energy needed to be added to the system for order to create order then natural selection could act on the simple life to better able to access and use energy to do life processes in their environment. Result: Stuff doesn’t happen unless the Second Law says it can Changes favored by second law: High energy  Low energy (ball rolling down a hill) Complexity  simplicity (Diffusion of molecules spreading out) Order  Disorder (Cherry Bomb)

The Second Law in Pictures Spontaneous! Spontaneous=NO EXTERNAL (ENERGY) INPUT releases energy to its surroundings Energy NOT evenly distributed = Entropy LOW Energy evenly distributed = INCREASE in entropy The amount of energy is the same but where it is located is different

Get out AP Equations Sheet

Chemical Reactions and the second LaW. . . When does a chemical reaction happen SPONTANEOUSLY? When the PRODUCTS have LESS energy than the REACTANTS This energy is called GIBBS FREE ENERGY (G) The CHANGE in energy is called ΔG (Δ=change) Spontaneous reaction: ΔG<0 (negative) {exergonic} ΔG can be calculated, using THIS equation: G= available energy to do work H= total energy in a system, such as the potential energy in a bond S= disorder of a system randomness Free Energy Change “available” to do work Enthalpy Change Total energy in the system Ex: PE in the bonds Entropy Change Disorder of a system randomness Temperature

That idea, Graphically

Can life rely ONLY on spontaneous reactions? Life Vs. The Second Law. . . Can life rely ONLY on spontaneous reactions? Spontaneous reaction is what the universe is doing (2nd Law) energy is being released A non-spontaneous reaction cannot happen unless coupled with a spontaneous reaction or free energy from the sun

Life: requires energy (order) Not-Life

Chemical Bonds and the Sun! Big Idea Life represents a DECREASE IN ENTROPY Thus: life processes (growth, reproduction, etc.) require a continuous INPUT of FREE ENERGY Free energy is energy available to do WORK Work is necessary to make non-spontaneous reactions happen SOURCES of free energy? Chemical Bonds and the Sun! ΔG<0 ΔG>0

A B + C D + E F Coupled Reactions Strategy: Couple (join) SPONTANEOUS reactions with NON- SPONTANEOUS reactions The ENERGY released from the SPONTANEOUS reaction can be used to POWER the NON-SPONTANEOUS reaction Low E Reaction A (Spontaneous ΔG<0) High E A B + C Energy (ATP) from A used to power B Reaction B (Non- Spontaneous ΔG>0) D + E F Low E High E

Next Step Highlight KEY SCIENTIFIC VOCABULARY in your notes ONLY KEY VOCAB Go through your supporting targets and answer them using your notes and table partners Due at the end of class WHEN DONE: start your homework on photosynthesis Available energy to work- chemical bonds and the sun Being able to grow, develop, reproduce, life processes, metabolize- doesn’t happen spontaneously needs energy to make it happen Energy carriers- ATP, Nadph, nadh create order which is the opposite of entropy.