Energy is the ability to do work (move or change matter) or produce heat. Energy exists in two basic forms: potential energy and kinetic energy. Potential energy is energy due to composition or position. (examples: gravitation + chemical) Kinetic energy is energy of motion. Copyright © McGraw-Hill Education Energy

In which figure does the electron have higher potential energy?

Read about different forms of E on notes Determine the form of E for each of the sources of our E consumption in US

Pros and cons of each electricity source

The law of conservation of energy states that in any chemical reaction or physical process, energy can be converted from one form to another, but it is neither created nor destroyed—also known as the first law of thermodynamics. Copyright © McGraw-Hill Education Energy

Discuss skier at top of hill: PE changing to KE Discuss skier at top of hill: PE changing to KE. Does all of the PE get converted to KE? PE= mgh KE= ½ mv2 How do mass and height affect PE?

Why do chemicals such as glucose and isooctane contain so much chemical (potential) energy?

Chemical potential energy is energy stored in a substance because of its composition. In glucose and isooctane, the electrons in the C-H bonds are in a high potential energy state. On whiteboards: Where did the electrons get this energy originally?

Photosynthesis What has more chemical potential energy: CO2 or C6H12O6 ?

Chemical bonds do not store energy Chemical bonds do not store energy. They certainly "contain" potential energy and the atoms want to move to a lower potential energy (become more stable). When methane, CH₄, forms, the valence electrons end up in more stable (lower energy) C-H bonds. These bonds are fairly strong, so methane is relatively inert. However, if you add energy to the methane in the form of a flame or a spark in the presence of oxygen, some of the molecules will have enough energy to overcome an activation energy barrier. Some of the C-H bonds will break. The electrons can then enter an even lower energy state by forming C=O and O-H bonds rather than staying as C-H and O=O bonds. So they “rearrange” themselves to form CO₂ and H₂O. The excess energy of 794 kJ..mol⁻¹ is released as heat, which we can then use to cook our food, among other things.

Thus, chemical bonds do not “store” energy Thus, chemical bonds do not “store” energy. The energy for breaking bonds comes only when stronger bonds are formed instead. This is the true driving energy for biochemistry, where cellular respiration provides energy by breaking the weaker bonds in carbohydrates and sugars and forming the strong oxygen bonds in carbon dioxide and water. More energy is "available" because the weaker bonds are broken in favor of the stronger bonds being formed. Many people say that ATP stores energy and releases it when the phosphoester linkage is broken and forms ADP. But it takes energy to break a phosphate group from ATP. Rather, ATP provides energy when it breaks the weakly bonded phosphoester linkages and forms more strongly bonded glucose or fructose phosphate molec

How is the energy from glucose or isooctane released? Discuss: How is the energy from glucose or isooctane released?

Chemical reactions change substances into different ones by breaking chemical bonds and forming new chemical bonds What do we call the inputs? The outputs?

Bond energy is the amount of energy that it takes to break a bond. Energy is _________ (required/ released) to break bonds. Energy is__________ (required/ released) when bonds form. https://www.youtube.com/watch?v=5-TPVHIi39w (show with magnetic molecules- hydrogen gas + oxygen gas water) https://www.youtube.com/watch?v=rfpv_e3Si8w

Energy needs to be added (absorbed) in order to break the bonds in the reactant molecules

When new bonds form to make the products, is energy absorbed or released?

Exothermic reactions release more energy than they absorb. Electrons in bonds of reactants are in a higher energy state than they are once they are in products Excess energy is released by the reaction.

What do we call reactions in which more energy is released than absorbed?

Endothermic reactions absorb more energy than they release. Electrons in bonds of reactants are in a lower energy state than they are once they are in products Energy is absorbed by the reaction to make up the difference.

Is photosynthesis exothermic or endothermic? 2. Are the electrons in a higher energy state in carbon dioxide or glucose?

A joule: SI unit of heat and energy 1 joule = 0.2390 calories. Measuring Energy calorie: the amount of energy required to raise the temperature of one gram of water one degree Celsius. The energy content of food is measured in Calories, or 1000 calories (kilocalorie). A joule: SI unit of heat and energy 1 joule = 0.2390 calories. Copyright © McGraw-Hill Education Energy