Warm-Up: What do you know about Chemistry? Draw and label an atom? (Hint: Proton, Neutron, Electron, nucleus) Draw a water molecule? (Hint: Think of the chemical formula!) Name 4 elements: ___________________ Name 2 reasons chemistry is important to living things…AKA BIOLOGY! Welcome to BioChemistry!

The Chemistry of Life

Look out for the special check mark to know which notes to write!  Look out for the special check mark to know which notes to write! On a checked slide with lots of notes, just write underlined text!

Elements  Fundamental forms of matter Each has only 1 type of atom Can’t be broken into simpler parts and keep their unique properties 92 elements occur naturally on Earth Watch the Elements SONG!

Most Common Elements in Organic Molecules (CHNOPS)  Most Common Elements in Organic Molecules (CHNOPS) Carbon Hydrogen Nitrogen Oxygen Also: Phosphorus and Sulfur Also: Calcium and Potassium

 Most abundant in organic molecules Most abundant in Earth’s atmosphere

What Are Atoms?  Video: What does an Atom really look like? Smallest particles that retain properties of an element Made up of subatomic particles: Protons (+) Electrons (-) Neutrons (no charge) # Protons or Electrons= Atomic Number # Protons + Neutrons= Atomic Mass Video: What does an Atom really look like?

A Peek at the Periodic Table Which are the most common in living things again?

 Isotopes Atoms of an element with different numbers of neutrons (different mass numbers, different weights!) Ex: Carbon 12 has 6 protons, ? neutrons Ex: Carbon 14 has 6 protons, ? neutrons 6 8

Radioactive Isotopes have excess neutrons  Radiation is mostly the extra neutrons that shoot out of the nucleus! They can act as tracers because they show up on X-Ray and radiation detectors Following tracers is useful in many areas of biology

Medical Uses of Radioactive Elements Swallow Barium  helps Doctors see the large intestines, which would not show on a normal x-ray.

What Determines How Atoms Interact and Bond?  What Determines How Atoms Interact and Bond? The number and arrangement of their electrons in the outer shell! Atoms are happy (stable) when their outer shells are full 1st Shell Full = 2 electrons 2nd Shell Full = 8 electrons

Bonds, Molecules, Compounds (Definitions)  Bond = a union between electrons of atoms Diatomic Molecule = two or more of the same type of atom (element) bonded together. Ex: H2, N2, O2, Compound = two or more different types of atoms (elements) bonded together. Ex: H2O

 Ionic Bonding An exchange (one gives, the other accepts) of electrons … An ion is a charged atom: it either lost electrons (+), or gained electrons (-) If one atom loses electrons (+), and another atom gains these electrons (-), then the charge difference attracts the two ions to each other

Table Salt is the most famous example of an ionic bond! Sodium’s outer shell has one electron Chlorine’s outer shell has seven electrons Na transfers electron to Cl forming Na+ and Cl- Ions attract and remain together as NaCl NaCl

 Covalent Bonding When atoms share a pair or pairs of electrons to fill outermost shell A single covalent bond shares 1 pair of electrons. A double covalent bond shares 2 pairs of electrons. A triple covalent bond shares 3 pairs of electrons.

 Hydrogen Bonding Hmm … To understand Hydrogen bonds, you must first understand Polarity! A molecule is polar when electrons are not shared equally, so … One part of the molecule is more positive and the other part is more negative!

Hydrogen Bonding (cont’d)  Hydrogen Bonding (cont’d) forms between the more “negative” atom in one polar molecule … and … the more “positive” atom in another such molecule. Usually, the more positive atom is Hydrogen. Forms between hydrogen and either nitrogen, oxygen or fluorine

Other Examples of Hydrogen Bonds one large molecule another large molecule a large molecule twisted back on itself Fig. 2.12, p. 27

Water is the classic example of Hydrogen Bonding!  H + H + H _ O + + + H + _ O

Let’s Make M & M Isotopes!

Get Started on your Vocabulary!

Exit: What do you know about Chemistry NOW? Draw and label an atom? Draw a water molecule? Label the polar ends Name 4 most common elements in living things: _______ Describe what happens to the electrons in the following: Ionic Bonding: Covalent Bonding: Name 3 reasons chemistry is important to living things…AKA BIOLOGY! Welcome to BioChemistry!