Notes 2-3 Energy and Matter
ENERGY Who remembers the definition of Energy? Who remembers the definition of Energy? The Ability to do WORK! The Ability to do WORK!
ENERGY All chemical and physical changes include a change in energy All chemical and physical changes include a change in energy
Law of Conservation of Energy Energy is neither created nor destroyed Energy is neither created nor destroyed It is only transformed (changed from one form to another) It is only transformed (changed from one form to another)
Forms of Energy Forms of energy that include changes in matter are: Thermal Energy, Chemical Energy, Electromagnetic Energy, and Electric Energy Forms of energy that include changes in matter are: Thermal Energy, Chemical Energy, Electromagnetic Energy, and Electric Energy
Thermal Energy Temperature = average energy of random motion of particles of matter Temperature = average energy of random motion of particles of matter Thermal Energy = total energy in all particles in an object Thermal Energy = total energy in all particles in an object Thermal energy is related to temperature because the energy always flows from warm matter to cool matter Thermal energy is related to temperature because the energy always flows from warm matter to cool matter Endothermic Change = energy is absorbed Endothermic Change = energy is absorbed Ex: Melting Exothermic Change = energy is released Exothermic Change = energy is released Ex: Combustion
Chemical Energy Stored in Chemical Bonds between atoms Stored in Chemical Bonds between atoms Bonds are broken and new bonds formed Bonds are broken and new bonds formed Ex: in foods, gas for cars, cells Ex: in foods, gas for cars, cells Usually involve transformations between chemical energy and thermal energy, like when burning a match Usually involve transformations between chemical energy and thermal energy, like when burning a match
Electromagnetic Energy Travels through space as waves Travels through space as waves Ex: Visible light, radiowaves, microwaves, x-rays, UV rays, infrared rays Ex: Visible light, radiowaves, microwaves, x-rays, UV rays, infrared rays Chemical changes can give off light (electromagnetic energy) Chemical changes can give off light (electromagnetic energy) Microwaves thaw frozen food (physical change) Microwaves thaw frozen food (physical change)
Electrical Energy Energy of electrically charged particles moving from one place to another Energy of electrically charged particles moving from one place to another Ex: electrons move from one atom to another in many chemical changes. Ex: electrons move from one atom to another in many chemical changes. Ex: using electrolysis to separate water molecules into oxygen gas and hydrogen gas Ex: using electrolysis to separate water molecules into oxygen gas and hydrogen gas
Potential Vs Kinetic POTENTIAL ENERGY: Energy waiting to be used Energy waiting to be used Ex: Food you eat Ex: Food you eat KINETIC ENERGY: Energy of Motion (Energy being used) Energy of Motion (Energy being used) Ex: You taking notes! Ex: You taking notes!
Transforming Energy Example 1: Burning Burning -Chemical change that transforms chemical energy and releases it as thermal energy (heat) and electromagnetic energy (light)
Transforming Energy Example 2: Photosynthesis Photosynthesis -Plants transform electromagnetic energy from the sun into chemical energy (sugar for plants)
Transforming Energy Example 3: You Try! You Try! What energy transformations occur when you ride a bike? What energy transformations occur when you ride a bike? There is potential energy in the food you eat. There is potential energy in the food you eat. Your cells transform food into chemical energy your body can use. Your cells transform food into chemical energy your body can use. Chemical energy is transformed to kinetic energy of moving muscles and thermal energy given off as heat. Chemical energy is transformed to kinetic energy of moving muscles and thermal energy given off as heat.