Chemistry of Life

The basics of Chemistry

Matter is recycled and rearranged for living organisms Living matter is made up of different substances. Example of substances: pure CO 2, glucose, pure salt, H 2 O….. CO 2 glucose

Atoms - Smallest unit of an element (with properties of that element) Nucleus - dense center containing: –Protons - positively charged particles –Neutrons - particles with no charge Electrons (e - ) - small, negatively charged particles that orbit nucleus in clouds or shells (2, 8, 8) –Valence e - - found in outermost energy level How many total e - ? How many valence e - ? What element?

A=P=E M=A+N Atomic number = Proton number = Electron number Mass = Atomic Number + Neutrons

How would an element’s identity change if you took away or added protons? Check for Understanding

The 17 essential elements in plants (autotrophs)… CHOPKINS Ca Fe Mg B Mn Cu Zn Mo Cl Carbon, Hydrogen, Oxygen, Phosphorous, Potassium, Iodine, Nitrogen, Sulfur, Calcium, Iron, Magnesium, Boron, Manganese, Copper, Zinc, Molybdenum, Chlorine C HOPKINS Café Managed by my cousin Mo Cline

Elements for Quiz

96% of living matter: C, H, O, and N 4% of living matter: Ca, K, P, S, Na, Cl, Mg, Fe, and trace elements

Hypothesize as to why these elements are near the top of the periodic table. (answer in the left margin) Check for Understanding

Atoms, Molecules and Compounds

Molecules and Compounds Molecule - 2 or more elements joined together by chemical bonds smallest unit of a compound

Chemical reactions 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 Lead to changes in substance or matter. Occurs when electrons are transferred between two atoms (lost, gained or shared)

Drawing Atoms As scientists, we want to be efficient Instead of drawing all of the electron shells, we only need to draw the valence electrons A Lewis Dot diagram will make drawing molecules and compounds easier

Lewis Dot Diagrams The inner shells are not involved in bonding, so we can ignore them Carbon is in group 14, so that means 4 valence electrons We only need the element symbol and the valence electrons

You try… What does the Lewis dot diagram look like for Oxygen? What does the Lewis dot diagram look like for Sodium? Hydrogen? How about Lithium? Why are they all the same? NaH Li

Ions = electrically charged matter Ions form when electrons are lost or gained. Ionic bonds form when a positive ion is attracted to a negative ion.

Making Salt…Lewis dot style (Ionic bond)  positive Na + attracted to negative Cl -

Covalent bond = two atoms sharing electrons “Strong” Relatively stable Hydrogen, oxygen, and nitrogen can readily form covalent bonds with carbon.

Hydrogen Bonding Weak bonds between a hydrogen of one molecule to an adjacent negative molecule Ex: attraction between water molecules.

Mixtures Physical combinations of substances There are several types of mixtures: solutions suspensions Colloids, or colloidal dispersions

Mixtures Air = solution Physical combinations of substances Cytoplasm = colloid Blood = suspension Jello = colloid Kool-Aid= solution