The Basics Of Life Chemistry

Matter, Energy, and Life All life forms are composed of matter and use energy to carry out processes. Matter is anything that has mass. Energy is the ability to do work.

Chemistry Chemistry is the science concerned with the study of the composition, structure, and properties of matter and the changes it undergoes. Both living matter and non-living matter have the same basic building blocks.

Two General Types of Energy Kinetic energy is the energy of motion. Potential energy is stored energy. It is energy that is not yet doing work. Potential energy is stored in matter and chemicals. It can be converted to kinetic energy to perform some sort of work.

1st Law of Thermodynamics The 1st law of thermodynamics is also known as the law of conservation of energy. Energy is never created or destroyed. Energy can be converted from one form to another, but the total energy remains constant.

Five Forms of Energy 1. Mechanical. 2. Nuclear. 3. Electrical. 4. Radiant. 5. Chemical. All of these forms can be either kinetic or potential.

Mechanical Energy Mechanical energy is associated with machines or things in motion. Mechanical energy becomes kinetic when objects come into motion.

Nuclear Energy Nuclear energy is energy from reactions at the atomic nucleus of matter.

Electrical Energy Electrical energy (electricity) is the flow of charged particles. All metabolic reactions involve electrical energy.

Radiant Energy Radiant energy takes many forms including, but not limited to, the following: Heat Visible light X-radiation Microwaves

Chemical Energy Chemical energy is a type of potential energy stored in matter. When chemicals are changed from one form to another, it is released as kinetic energy. Cellular respiration is the method living things utilize to release chemical energy.

Atom Atoms are the smallest units of matter that can exist alone. Elements are fundamental chemical substances made up of collections of only one kind of atom. There are over 100 different elements.

Structure of the Atom 3 major subatomic particles: Neutrons. Protons. Electrons. Atomic nucleus – the central core of the atom where the mass is concentrated.

Subatomic Particles Neutron – a heavy subatomic particle that does not have a charge. Located in the atomic nucleus. Proton – a heavy subatomic particle with a positive charge. Located in the atomic nucleus. Electron – a light subatomic particle with a negative charge that moves around the outside of the nucleus in energy levels.

Atomic Number All atoms of an element have the same number of protons. The atomic number of an element is the number of protons in an atom of that element. Each element has a unique atomic number.

Atomic Mass Unit The mass of a proton is 1.67 x 10-24 grams. Since this mass is awkward to express, 1 proton is said to have a mass of 1 atomic mass unit (AMU).

Neutron Number All atoms of the same element have the same number of protons and electrons; However, they do not always have the same number of neutrons. They can have more or fewer neutrons. Each atom of the same element with a different number of neutrons is called an isotope of that element.

Atomic Weight The atomic weight of an element is an average of all the isotopes present in a mixture in their normal proportions.

Mass Number The number of protons and neutrons in the nucleus of an atom is called the mass number.

Comparison of Atomic Particles Protons Neutrons Electrons Location Nucleus Outside nucleus Charge Positive (+) None (neutral) Negative (-) Number Present Identical to Atomic # Atomic Weight Minus Atomic # Equal to # of protons Mass 1 AMU 1/1,836 AMU

Periodic Table of the Elements The table provides information about all known elements. The atomic weight increases as you read left to right along the periods. Families go from top to bottom and consist of elements with similar chemical properties.

1st Draft of the Periodic Table by Dmitri Mendeleev (1834-1907)

Elements in Living Things 11 main elements comprise living things. C, H, O, P, K, I, N, S, Ca, Fe, and Mg. CHOPKINS CaFé, Mighty Good!

Position of Electrons Electrons occupy certain areas around the nucleus known as energy levels. Each energy level contains electrons movement at about the same speed (approximately the same level of kinetic energy).

Position of Electrons Energy levels are numbered in increasing order with level 1 closest to the nucleus. Electrons move in spherical or figure 8 patterns around the nucleus. The first energy level is full when it has 2 electrons, the second energy level is full when it has 8, the third level 8, and so on.

Octet (8) Rule The octet rule states that atoms seek a stable, filled outer energy level. Hydrogen and Helium have a filled outer energy level with 2 electrons; However, all other atoms have 8 electrons in their outer energy levels.

Octet (8) Rule Atoms attempt to acquire this stable level through chemical reactions with other atoms. Atoms such as He and Ne have full outermost energy levels. Therefore they normally do not undergo chemical reactions. They are referred to as noble or inert.

Valence Shell The valence shell is the outermost shell of an atom in its uncombined state. The electrons of the valence shell are the ones that are most likely to contribute to chemical reactions and bond with other atoms. Electrons in this shell are referred to as valence electrons.

Molecule A molecule is the smallest particle of a chemical compound that is a definite and distinct, electrically neutral group of bonded atoms. Some atoms bond to form diatomic molecules (di = two). H2, O2, and N2 are diatomic gases in our atmosphere. Some elements such as the noble gases He and Ne exist as monatomic elements.

Compound A compound is a chemical substance made up of two or more elements combined in a specific ratio and arrangement. Chemical bonds are the attractive forces that hold atoms together. Molecules can consist of two or more atoms of the same element (i.e. N2 or O2) or specific numbers of different elements.

Formula The formula of a compound tells us: H20. What elements it contains. The proportions of these elements. H20.

Molecules and Kinetic Energy All matter has kinetic energy. Molecules are in constant, random motion. They diffuse from areas of high concentration to areas of low concentration. The rate of diffusion is dependent upon the temperature of the room.

Temperature Vs. Heat Temperature is a measure of the average kinetic energy of the molecules making up a substance. Heat is the total internal kinetic energy of molecules, which is measured in calories. A calorie is the amount of heat necessary to raise the temperature of 1 gram of water 1 degree Celsius.

Temperature Vs. Heat Heat is a quantity of energy. Temperature deals with comparative hotness or coolness of things (how fast molecules are bumping into one another or their kinetic energy). Adding heat to molecules will increase their temperature.

Phases of Matter The phases of matter are determined by the following: The amount of kinetic energy molecules have. The strength of the attractive forces between molecules. The arrangement of the molecules. Three phases: Solid. Liquid. Gas.

Solid A solid consists of molecules with strong attractive forces and low kinetic energy. The molecules vibrate in place and are at fixed distances from one another.

Liquid A liquid has molecules with enough kinetic energy to overcome the attractive forces that hold the molecules together. The molecules are still strongly attracted to one another, but they are slightly farther apart.

Liquid The molecules can slide past one another. Liquids change shape, but they maintain their volume. Liquids flow and are called fluids.

Gas A gas is made of molecules that have a great deal of kinetic energy. The attraction of the molecules to one another is overcome by the speed with which the individual molecules move.

Gas The molecules collide against one another and push each other apart. Therefore, gases expand to fit their container. Vapor is the gaseous form of a substance that is usually in a liquid phase.

Chemical Reaction A chemical reaction is a change in matter in which different chemical substances are created by either forming or breaking chemical bonds. A chemical reaction involves atoms interacting with other atoms to fill their outermost energy level with electrons.

Chemical Reaction The interacting atoms become attached or bonded to one another. Two types of bonds: Ionic. Covalent.

Ionic Bonds A positively or negatively charged atom or molecule is called an ion. Ionic bonds are formed after atoms transfer electrons to achieve a full outermost energy level. Electrons are donated or received during the transfer to form positive and negative ions (ionization).

Covalent Bonds A covalent bond is a chemical bond formed by the sharing of electrons. A covalent bond in which a single pair of electrons is shared is called a single covalent bond (single bond). Double bond – two pairs of electrons are shared by two atoms. Triple bond – three pairs.

Hydrogen Bonds Hydrogen bonds are due to the unequal sharing of electrons and the resulting polar nature of the molecule. Hydrogen bonds can be either intermolecular or intramolecular. Hydrogen bonds hold molecules together, they do not bond atoms together. Therefore, they are not true chemical bonds.

Mixtures and Solutions A mixture is matter that contains two or more substances that are not in set proportions. A solution is a liquid mixture of ions or molecules of two or more substances. The process of making a solution is called dissolving.

Mixtures and Solutions The solvent is the component present in the larger amount. The solute is the component that dissolves in the solvent. Aqueous solution – solid, liquid or gas dissolved in water. The amounts of solute and solvent are the concentration of a solution.