Composition of Matter Energy Solutions

Composition of Matter  Why discuss chemistry in biology class? The structure and function of all living things are governed by the laws of chemistry

Matter  Makes up everything in the universe  Anything that occupies space and has mass Mass is not = to weight ○ Weight is the pull of gravity on an object (mass would not change because it is the “quantity of matter” an object has… ○ You would still be the same “being” on Earth and on the moon = your mass doesn’t change…HOWEVER…your weight would be significantly less on the moon due to the pull of gravity

Chemical changes in matter  Essential to all life processes  Living things are made up of the same kinds of matter that make up nonliving things  Understanding changes in matter = understanding of life processes of organisms

Elements  Pure substances that cannot be broken down chemically into simpler kinds of matter 90% of mass of all kinds of living things is composed of combinations of 4 elements: ○ Oxygen (O) ○ Carbon (C) ○ Hydrogen (H) ○ Nitrogen (N)

Chemical Symbols Atomic Number Chemical Symbol Atomic Mass Name

Atoms  Simplest particle of an element that retains all of the properties of that element Nucleus = core of atom ○ Made of protons (+) and Neutrons (no charge) All atoms of a given element have same # of protons Atomic # = number of protons Electrons ○ High energy particles; negatively charged; move about nucleus at very high speeds in “energy levels” ○ First e- level = up to 2 e- ○ Second e- level = up to 8 e-

Atomic Energy Levels

Compounds  Under natural conditions, most elements do not exist by themselves  A compound is a pure substance that is made up of atoms of two or more elements that are fixed = water: H 2 O = chemical formula indicates that the atoms always combine in a proportion of two Hydrogen atoms to one Oxygen atom

Making Compounds  Stable atom = outermost energy level is filled  Most atoms are not stable in natural state = meaning they tend to react/combine with other atoms in order to achieve stability  Undergo chemical rxns to achieve stability = chemical bonds are broken; atoms are rearranged; new bonds are made

Bonds  Covalent = 2 atoms share one or more pairs of e-  Ionic= one e- gets transferred from one atom to another, resulting in more stability and giving both atoms a charge of + or -

You payin’ attention????

What are you to do now?  You are going to complete a “Guided Notes” (GN) activity… On page 35 of your textbook, you will notice that there are 4 objectives listed. Make a chart/table using the objectives and take notes from the reading. Ex: Objective Notes List the three states of matter, and explain how matter can change state Your notes will go here You can bullet Leave space so that you can take notes in class!

Back to our notes!!!!!

Energy - E  Energy is the ability to do work  Biological systems need/use: chemical energy, thermal energy, electrical energy, and mechanical energy  Free energy = energy available for work (cell processes would benefit from this)

Do Right this Very Minute (DRTVM)  Two Truths and a Lie…. Take an index card from the front desk From the homework (a few nights ago), write down two truths and a lie about “Energy” You have 2 minutes! When 2 minutes are up…you are to find 3 people NOT at your table and try to trick them… Write down all 3 names on the other side of your card and write down if they picked the lie or not… You have 5 minutes!

States of Matter  Solid, liquid, or gas  Atoms in constant motion…their speed determines the state… Solid = particles are tightly linked in definite shape (fixed volume and shape) Liquid = particles are not as tightly linked (fixed volume) Gas = particles move most rapidly; move freely; little or no attraction to each other *Thermal energy must be added to change a state

Energy and Chemical RXNs

Chemical Rxns  Our bodies need a lot of energy…we get it from breaking down sugars from food into CO 2 and H 2 O  Exergonic = chem. rxn where E is released  Endergonic = chem. rxn where E is absorbed

Activation E  What gets you up and moving faster???

Really…activation E  the amt of E needed to start a rxn  Catalysts lower the amt of activation E necessary for rxn  Enzymes are important catalysts to living things – specific to individual chemical rxns

E movement  Constant flow of energy into and throughout living things  Many involve transfer of e- between atoms

Redox Reactions – These work together When a compound becomes “oxidized” it loses its electrons to another compound… When a compound gains electrons, it becomes negatively charged, or reduced.

Solutions (solns)  Solution (soln) – 1+ substances are = distributed in another substance  Solute – dissolved substance  Solvent – does the dissolving (water is the universal solvent)  Concentration – measurement of amt of solute dissolved in a fixed amt of soln  Saturated soln – no more solute can dissolve  Aqueous soln – water is solvent

Dissociation of H 2 O  Breaking apart of water

Acids and Bases When an acid is introduced into a neutral solution, it adds H+ ions When a base is introduced into a neutral solution, it adds OH- ions

pH  Scale developed to compare the relative concentration of hydronium ions and hydroxide ions in a solution  Ranges from 0 to 14  0 = very acidic  14 = very basic  7 = neutral (water) See Figure 2-10 on page 42

Buffers Definitely NOT this guy!  Chemical substances that neutralize small amts of either an acid or a base added to a soln