The Chemistry of Life

 In your notebooks: Today’s date Title: Unit: The Chemistry of Life With a partner, think about this question: Why is chemistry important in biology? Make a list of 3 ways chemistry affects living things and/or chemical processes living things perform.

The Chemistry of Life  Big Idea: Matter and Energy  Essential question: What are the basic chemical principles that affect living things? Guiding questions: 1.What is the matter in organisms made of? 2.Why are the properties of water important to organisms? 3.How do organisms use different types of carbon compounds? 4.How do chemicals combine and break apart inside living organisms?

Basic Chemistry  Atoms are the basic unit of matter  Elements are pure substances which consist of entirely one type of atom  Molecules and compounds are formed when elements bond together  All things (living and nonliving) on Earth are composed of atoms, molecules, and compounds

Subatomic Particles: What makes up an atom? Electrons, Protons, Neutrons  The number of protons (+) determines chemical behavior  The number of electrons (-) determines how it will react with other atoms  The number of neutrons (no charge) determines radioactivity (*isotopes)

Element, molecule, or compound? 1. Ca (calcium) 2. OH - (hydroxide ion) 3. O 2 (oxygen) 4. H 2 0 (water) 5. C 6 H 12 O 6 (glucose) 6. Are these examples of living things?

Elements of Life  Carbon  Hydrogen  Nitrogen  Oxygen  Phosphorus  Sulfur  Chlorine Cl  Potassium K  Calcium  Sodium Na

Ions  When an atom gains or loses an electron it also gains a charge (+ if loses an electron) or (- if gains an electron)  When an atom or groups of atoms has a (+) or (-) charge it is called an ion  Our heartbeat, taste, and nervous systems all utilize ions to function

 How do elements form the molecules and compounds of life?

Types of Bonding: Covalent Bonds  Covalent bonds: When two atoms share electrons equally The electrons move around the nucleus of both atoms in the bond Examples: H 2 O 2 H 2 0

Types of Bonds: Ionic Bonds  Formed when electrons are transferred from one atom to another; one atom gains e- and one atoms loses e-

Bonding

Chemical Formulas  The chemical formula of a substance indicates: The elements in the molecule The number of atoms of each element in the substance  Example:6H 2 S0 4 2 atoms of the element hydrogen; 1 atom of the element sulfur; 4 atoms of the element oxygen  A number in front of substance indicates how many molecules of that substance there are: There are 6 molecules of H 2 S0 4 in the example

Chemical Reactions  Are changes which result in the formation of one or more new substances The starting materials are called the reactants (what is reacting) The ending materials are called products (what is being produced)

Chemical Reactions  During chemical reaction bonds between molecules can be broken (not always) and new bonds are formed Example: A + B  C Bond between A and B forms new compound C Example: AB + CD  AC + BD Bond between A and B broken Bond between C and D broken Bond between A and C forms Bond between B and D forms

Chemical Reactions

Chemical Equations  Identify the reactants and products of a chemical reaction  Gives the chemical formula of each substance involved in the reaction (the reactants and the products)  Looks like this: X + Y  XY AB + CD  AC + BD Reactants on LEFT of arrow Products on RIGHT of arrow

Water  Essential to life processes Transport materials Molecules can dissolve in it and react

Polar Molecule  Sometimes when atoms form covalent bonds, they do not share electrons equally There is an unequal distribution of charge (since electrons have a negative charge)  In other words, one side of the molecule is “positive” and the other side of the SAME molecule is “negative”

Polar Molecule – H 2 0

 For a water molecule, the negative side is the Oxygen and the positive side in the Hydrogen (the “ears”)

Non-Polar Molecule  A non-polar molecule is one that the electrons are distributed more equally There is NO “negative” or “positive” side

Non-Polar Molecule – CO 2

Hydrogen Bonding  The “positive” side of one water molecule is attracted to the “negative” side of another water molecule  These bonds are weak  Attract water molecules to each other

Hydrogen Bonding of Water

 No electrons are actually shared between water molecules  Hydrogen bonds weaker than covalent bonds; easily break and form again

Cohesion  The tendency of “like” molecules to be attracted to one another  Molecules “stick” to each other

Surface Tension – A Special Type of Cohesion  Surface tension due to cohesion of water  Cohesion of the top layer of the water

Adhesion  The sticking together of molecules of different substances  Examples: water adhering to paper, plastic, or glass