Introduction to Chemistry for Biology

“Do Now” – 9/19/16 in your notebook What are livings things made up of? What are cells made up of?

Matter Anything that has mass and volume – anything that takes up space Matter is made up of atoms What are the three parts of an atom? Do any of the parts have a charge? What are they? Very loose definition of matter

Atoms, Molecules, and Compounds Problem: H is an atom, O is atom – how do we get H20? Part I, basic info: H20 is called the molecular formula for water What does the little 2 in H20 mean? What would 6H20 mean? Part II: How do atoms “stick” together? Atoms can form bonds – any of several forces by which atoms are bound in a molecule

Bonds Covalent bonds Ionic bonds Using the model to the right, list one similarity between ionic and covalent bonds and one difference

Bonds Covalent bonds Electrons between atoms are: Ionic bonds

The bonds between carbon and oxygen are covalent bonds Let’s look at how oxygen and hydrogen bond to form a carbon dioxide molecule The bonds between carbon and oxygen are covalent bonds

Let’s look at how sodium and chlorine bond to form a NaCl molecule This bond is ionic: Sodium is “giving” one of its electrons to chlorine Chlorine is “taking” one of sodium’s electrons Problem: Why does sodium have a + sign now? Why does chlorine have a – sign now? Hint: it has to do with the electron!

Definition: an electrically charged atom or group of atoms formed by the loss or gain of one or more electrons Let’s practice! Ions

Molecules and Compounds When bonds occur between atoms, molecules and compounds are made Example of molecules: O2, H2, I2, H20 Examples of compounds: Co2, H20, C6H12O6 How come O2 isn’t considered a compound? Compare O2 and CO2 – how are they different?

Molecules and Compounds Molecule - two or more atoms that are chemically joined together H2, O2, H2O Compound - a molecule that contains more than one element H2O, C6H12O6 Let’s practice!

When atoms bond forming molecules, what process has “happened?” Chemical reaction: a chemical change that occurs when two or more substances combine to form a new substance Between atoms like Na+ + Cl-  NaCl Or between molecules like CO2 + H20  C6H12O6 + O2

Chemical Equations Chemical equations show us the reactants and products of a chemical reaction Example of the chemical equation which illustrates the chemical reaction between carbon dioxide and water which forms glucose and oxygen CO2 + H20  C6H12O6 + O2 Which are reactants and which are products? Let’s practice!

Properties of Water

Polarity

Polar covalent bonds Electrons shared by the atoms spend a greater amount of time around one atom than the other The result of unequal electron sharing is a charge separation in the molecule, where one part of the molecule has a partial negative charge and the other has a partial positive charge.

Why is there a hydrogen bond attraction between H and O? Compare and contrast the covalent bonds and hydrogen bonds above. Why is there a hydrogen bond attraction between H and O?

Hydrogen Bonds Attraction between the positive and negative poles of charged atoms In a water molecule, which atom(s) is the negative pole? What atom(s) is the positive pole? Given that information, which parts of water molecules should be attached to one another? Is that what we saw in the POGIL and models today? 