Basic Chemistry

Matter-anything that has mass and takes up space Mass-the amount of matter in an object Element-a substance that cannot be ordinarily broken down to form simpler kinds of matter

20 Important Elements/Symbols Carbon C Hydrogen H Oxygen O Nitrogen N Calcium Ca Phosphorus P Potassium K Sulfur S Sodium Na Chlorine Cl Magnesium Mg Iron Fe Zinc Zn Copper Cu Iodine I Manganese Mn Boron B Chromium Cr Fluorine F Cobalt Co

Atom-the simplest particle of an element that retains all the properties of that element 3 Subatomic Particles Protons-have a positive charge and are located in the nucleus (p + ) Neutrons-have no charge (are neutral) and are located in the nucleus (n 0 ) Electrons-have a negative charge and are located on the atom’s energy levels (e - )

The Rule of Eight: Most atoms need 8 electrons in their outermost energy level to be stable. The Exceptions: Hydrogen and Helium need 2 electrons in their outermost energy level to be stable.

Compounds-a chemical combination of 2 or more elements (atoms); can be broken down Chemical Bonds-the attachments that hold atoms together in a compound Types of Bonds: Covalent Bonds Ionic Bonds

Covalent Bond-forms when 2 atoms share one or more pairs of electrons Water-H 2 0- is a covalently bonded compound Ionic Bond-forms between 2 oppositely charged ions (an ion is an atom that has either gained or lost electrons and has a charge); this bond involves the transfer of electrons Table Salt-NaCl-is an ionic compound

Parts of a Chemical Reaction Reactants-typically found on the left side of a chemical equation; they represent what is needed for the reaction to occur Products-typically found on the right side of a chemical equation; they represent what is produced by the reaction

2 Types of Chemical Reactions Exergonic Reactions-involve the release of energy Endergonic Reactions-involve the absorption of energy

Activation energy-the amount of energy needed to start a reaction; represented as the “hump” on a reaction graph Catalysts-molecules that lower activation energy so that reactions occur more quickly; can lower the “hump” Enzyme-a biological catalyst (see the definition of catalyst above)

Solution-a mixture in which one or more substances is completely dissolved in another 2 Parts of a Solution Solute-the substance that is dissolved Solvent-the substance that does the dissolving

Aqueous Solution-a solution where water is the solvent pH-a measure that determines if a substance is an acid or a base pH scale=0 to 14 Below 7=Acid (Strong acids are near to 0) Above 7=Base (Strong bases are near to 14) 7=Neutral

Acid-a substance that increases the concentration of hydronium ions when added to an aqueous solution Hydronium Ion=H 3 O + Base-a substance that increases the concentration of hydroxide ions when added to an aqueous solution Hydroxide Ion=OH -

Neutral solutions have equal concentrations of hydroxide and hydronium ions Buffers-prevent major changes in pH and can neutralize small amounts of acids or bases (buffers are essential to pH homeostasis in living things)

Seven Characteristics of Water In a water molecule, the hydrogen atoms are attached to the oxygen atom by covalent bonds. Water is polar. This means that it has unequal areas of charge due to unequal sharing of electrons.

Two or more water molecules are attached to each other by hydrogen bonds. Water is the universal solvent. It can dissolve other polar compounds as well as ionic compounds due to its polarity. Water molecules are attracted to other water molecules. This is called cohesion.

Water molecules are attracted to other types of molecules. This is called adhesion. Water must gain or lose a relatively large amount of energy for its temperature to change. This is called temperature moderation.