BIO I HONORS RUPP Chemistry

Matter Everything in the universe is made of matter

Mass Weight Quantity of matter an object has Mass never changes unless matter is added or taken away from the object The pull of gravity on mass affects weight Your weight on Earth or your weight on the Moon Matter con’t.

Elements Pure substances that cannot be broken down into simpler substances More than 90% of living things are made of O, N, C, and H Two other very important elements are S and P SPONCH elements

Where are the SPONCH elements?

Atoms Simplest particle of an element that retains characteristics of that element Atom structure  Nucleus  Electrons

Atoms con’t.—Nucleus Central core Protons Neutrons Mass of the atom is carried by the nucleus

Atoms con’t.—Electrons High energy Little mass Move around the nucleus in energy levels Outer electrons have more energy than inner electrons Each energy level holds certain numbers of electrons

How to read the Periodic Table!

Compounds Most elements form compounds under normal circumstances A pure substance made of atoms of two or more elements

Compounds con’t. Water Physical and chemical properties of atoms and compounds differ  O 2 is a gas  H 2 is a gas  H 2 O is a liquid

Compounds con’t. Compounds form depending upon the electrons in the outer energy level Stability Some elements do not react O, N, C, H react readily

Covalent Bonding Electrons are shared Molecules are formed

Ionic bonds Electrons are transferred Table salt example  Sodium loses an electron  Chlorine gains an electron Positive and negative ions attract to form bond

Energy and Matter Energy is ability to do work Forms of energy  Light  Heat  Chemical  Electrical  Mechanical

Energy and Matter con’t. Energy available to do work is called free energy States of matter  Solid—fixed volume and shape  Liquid—conforms to container and has fixed volume  Gas—fills volume of container and has no fixed volume  Plasma

Energy and Reactions Reactants Products Energy transfer  Exergonic—release energy—hot reactions  Endergonic—absorb energy—cold reactions

Activation Energy Energy needed to start a reaction Catalysts—substances that reduce activation energy Enzymes—catalysts found in living things

Reduction Oxidation Gains electrons Becomes negatively charged Think chlorine in the ionic bond example Loses electrons Becomes positively charged Think sodium in the ionic bond example Redox Reactions

Redox Reactions con’t. OiL RiG

Solutions Can be mixtures of solids, liquids, or gases Solute Solvent Concentrated Saturated Aqueous

Acids and Bases

Acid Base H+ ions Hydronium ions Sour taste Highly corrosive HCl (hydrochloric acid) Citrus juices OH- ions Hydroxide ions Bitter taste Very slippery because they react with oils Soaps Bleach Acids and Bases con’t.

pH A scale that relates numbers of hydronium ions to hydroxide ions Range from 0 to 14  0 acidic  7 neutral  14 basic Logarithmic  pH 4 has 10x more hydromium than pH 5 and 100x more than pH 6

Buffers Chemical substances that neutralize acids or bases Extremely important to life  Enzymes function in very narrow pH ranges  Body fluid pH scale (page 42) Buffer systems maintain the body’s pH at normal and safe levels