Matter and Energy

1. Matter and Energy Energy Reactions

2. Atoms and Elements • All matter is composed of atoms. • Atoms • are microscopic particles, composed of protons neutrons and electrons • Atoms come in over 110 types called elements. • Each element has a name and symbol. • Most living things are composed primarily of 4 elements; • Carbon (C) • Hydrogen (H) • Oxygen (O) • Nitrogen (N).

3. Elements and Molecules and Compounds • Elements may exist as single atoms, molecules or compounds • Molecule: • consists of 2 or more atoms combined in a definite ratio. • Must be neutral • held together by covalent bonds. • Ex. Water • Compoundisa pure substances composed of atoms from two or more different elements: • NaCl • HCl • CO2

4. Mixtures • Mixture: • collection of two or more substances physically mixed together is called a mixture. • Most mixtures can be separated by physical or chemical means. • Homogenous: • mixtures contain substances that are uniformly distributed: • Most beverage and liquids fall into this category • Heterogeneous: • mixtures contain substances that are not uniformly distributed, such as salad dressing or salsa.

5. Mass and Energy • Mass and energy are closely related to the theory of relativity, by Albert Einstein • E=mc2 • In this equation • E = energy • m = mass • C = speed of light in a vacuum (2.998 x 108 m/s)

6. Energy Types • Energy • the amount of work required to make some kind of a change. • Heat, light, sound, are all forms of energy. • Energy is present in all substances. • Chemical Energy: • is the energy that matter possesses because of its chemical make-up. • Thermal Energy: • is the energy released due to the motion of atoms and molecules • Mechanical Energy: • is the energy released to the movement of object against another object

7. Release and storage of energy • Energy is released any time matter undergoes a change whether is be chemical or physical • endothermic • The absorption of energy during a phase change reaction • exothermic • The release of energy during a phase change reaction

8. Chemical energy • Law of conservation of energy • During any physical or chemical change the total amount of energy remains constant. • Energy can not be created nor destroyed • energy in = energy out • Law of conservation of mass • During any physical or chemical change the total amount of matter remains constant. • mass in = mass out

9. Energy Transfer as Heat • Temperature • measure of the average kinetic energy of the particles in a sample of matter. • Kinetic energy is the amount of energy released by the movement of atoms.

10. Measuring temperature • Temperature is measured using these units • Fahrenheit • °Celsius • °Kelvin • Kelvin is based on the average kinetic energy of molecules • 0 K is considered absolute zero • The point at which there is no molecular movement

11. Key temperatures • Freezing Point of Water Boling Point of Water • K 273 373 • C 0 100 • F 32 212

12. Temperature conversions • Celsius -> Kelvin • x°C+ (273.15)= K • 20°C + 273.15 = 293.15 K • Kevin -> Celsius • °K –273 = Celsius • 373°K –273 = 100 °C