Chapter 2 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.

Matter, Energy, and Life Matter is anything that has mass and occupies space. Energy is the ability to do work. There are two types of energy: Potential energy Stored energy, available to do work Kinetic energy Energy of motion Potential energy can be converted to kinetic energy to do work.

Law of Conservation of Energy Energy is never created or destroyed. The first law of thermodynamics Energy can be converted from one form to another, but the total energy remains constant. An object at the top of a hill has potential energy based on its location. When the object rolls down the hill, the potential energy is converted to kinetic energy.

Forms of Energy There are five forms of energy: Mechanical energy Energy of movement Nuclear energy Energy from reactions involving atomic nuclei Electrical energy Flow of charged particles Radiant energy Energy in heat, light, x-rays and microwaves Chemical energy Energy in chemical bonds

What is the nature of matter? Atoms The smallest units of matter that can exist separately Elements Chemical substances composed of the same kind of atoms Listed on the periodic table Each element is represented by a symbol of one or two letters. The principal elements that comprise living things are: C, H, O, P, K, I, N, S, Ca, Fe, and Mg.

The Periodic Table of the Elements

Atomic Structure Atoms are composed of: The atomic nucleus Electrons Protons - positively charged Atomic number-the number of protons All atoms of the same element have the same number of protons. Neutrons – no charge Electrons Orbit the nucleus in energy levels Are constantly in motion

Atomic Structure

Elements Atoms of the same element have equal numbers of electrons and protons. Thus, they have a neutral charge. Isotopes Atoms of the same element that have different numbers of neutrons. Atomic weight-the average of all of the isotopes in a mixture. Mass number The sum of protons and neutrons in the nucleus.

Isotopes of Hydrogen

Electrons Electrons occupy specific energy levels around the nucleus. Electrons closest to the nucleus have the lowest energy. Energy levels hold specific numbers of electrons. The first energy level can have up to 2 electrons. All other energy levels can have up to 8 electrons. Atoms seek to have a full outer energy level. Atoms that have full outer energy levels are inert. Other atoms seek to fill their outer energy levels through chemical bonds.

Electrons

The Formation of Molecules Molecules consist of two or more atoms joined by a chemical bond. A compound is a chemical substance made of two or more elements combined in chemical bonds. The formula of a compound describes the nature and proportions of the elements that comprise the compound. H2O

Molecules and Kinetic Energy Molecules are constantly in motion. Temperature is a measure of the average speed of the molecules in a substance. The greater the speed, the higher the temperature. Measured in Fahrenheit or Celsius Heat is a measure of the total kinetic energy of molecules. Measured in calories (amount of heat that will raise 1g of water 1 degree Celsius). Heat and Temperature are related. Add heat energy to a substance and the molecules will speed up, and the temperature will rise.

Kinetic Energy, Physical Changes and Phases of Matter Three phases of matter Solid Liquid Gas The phase in which a substance exists depends on its kinetic energy and the strength of its attractive forces. Solids-strong attractive forces, low kinetic energy, little to no molecular movement. Liquid-enough kinetic energy to overcome the attractive forces; more molecular movement. Gas-high kinetic energy, little to no attractive forces; maximum movement.