Chemistry Pre-Quiz!

Question #1 Biochemistry is the study of ____________.

Question #2 An atom consists of protons, neutrons, and ____________.

Question #3 The molecular formula for water is ____________.

Question #4 Which is the smallest? Organism Cell Atom Compound

Question #5 Glucose is an example of a monosaccharide. True or False?

Chapter 2 The Chemistry of Life

Why do biologists need to study chemistry? All life forms are MATTER and all matter is made up of chemical parts. Matter = anything that has a MASS and VOLUME that can be measured. Examples of Matter (living and nonliving) All matter has both physical and chemical properties.

Physical Properties Can be observed and measured without permanently changing the identity of the matter Observed by the senses - taste, smell, shape, color, texture, melting and boiling points.

Chemical Properties Chemical properties can change a substance into a new substance through a chemical reaction. New substance is created and permanently altered! Rusting (oxidation) and combustion (flammability) Examples of chemical reactions

Levels of Organization (Largest Smallest) Organism Organ Systems Organs Tissues Cells Cell Organelles Molecule/Compounds Atoms

Ch. 2- Section 1

ATOMS Smallest, indivisible unit of matter. Extremely small! (100 MILLION atoms lined up end to end would only equal 1 cm in length!) *However, an atom is made up of smaller parts called SUBATOMIC PARTICLES.

ATOMS (continued) Center of Atom = Nucleus Subatomic Particles = Protons, Neutrons, Electrons Protons - positively charged particle (+1) Neutrons- particle with NO CHARGE; neutral (0) Electrons- Negatively charged particle (-1)

ATOMS (continued) Nucleus contains protons AND neutrons. Electrons circle around the nucleus in electron clouds or orbitals or valence shells.

ATOMS (continued) Every atom has an ATOMIC NUMBER. The atomic number tells you a lot of information. This number tells you the type of atom you have. (Element name) This number ALWAYS tells you the # of Protons in the atom. The atomic # is usually the number of neutrons and electrons, also. (not always!) Example: Atomic Number of 6 = 6 Protons, 6 Neutrons in the nucleus of the atom. Use Periodic Table of Elements to look up element name for atomic number 6 = Carbon

Elements Every element consists of only 1 type of atom. Every element has a DIFFERENT atomic number and its own symbol on the Periodic Table (PT). 109 elements on the PT, 90 are found in nature, 19 were formed in a laboratory by scientists.

Using the Periodic Table Below the Symbol (C) you’ll find the element’s atomic mass. Atomic Mass = Sum of protons + neutrons

Drawing Atomic Structures Look up element on the Periodic Table. Write down Atomic Number. Draw Nucleus with 3 orbitals surrounding it. Inside nucleus, write # of protons (p+). Inside nucleus, write # of neutrons (n0). Fill in orbitals with correct number of electrons. *First orbital gets only 2 electrons. *Additional electrons, fill 2nd orbital. (up to 8 e-) *More electrons will go into 3rd orbital. (up to 8 e-).

Drawing Atomic Structures Example: CARBON 6 p+ 6 n0

PRACTICE! Drawing Atomic Structures Draw the following elemental atoms. Oxygen Nitrogen

Chemical Elements & Compounds Remember! The atomic number of an element NEVER changes! IT IS ALWAYS THE # OF PROTONS IN THE NUCLEUS! However, the number of NEUTRONS can vary from one atom of that element to the next.

Isotopes Examples: 13C 14C All are Carbon atoms, just with different atomic MASSES! (same atomic #) Atoms of the same element, same number of protons, but different # of neutrons are called isotopes.

Radioactive Isotopes The nuclei of some atoms are unstable and will from time to time break down, releasing matter and energy that we call radiation. Atoms that emit (give off) radiation are said to be RADIOACTIVE. Radioactive Isotopes have many uses for living organisms, such as diagnosing and treating diseases, sterilize food, and measuring the ages of things, like trees or rocks.

Radioactive Isotopes (continued) Examples: Iodine - 131 (131I): injected into humans to study the function of the thyroid gland. Can be seen through special equipment that picks up on the radiation energy given off by this isotope as it travels through the body. Carbon-14 (14C): used to treat brain tumors and track the ages of trees and fossils.

Chemical Bonding When individual atoms interact, they form chemical bonds. When chemical bonds form between 2 or more atoms, your result is a chemical compound. However, atoms combine in a certain way and follow a specific set of rules! The rules affect the electrons in the outermost orbital, or VALENCE ELECTRONS.

VALENCE ELECTRONS When the outermost orbital is full with the maximum number of electrons, the atom is very stable (happy!). These atoms are unreactive and do not combine with other atoms to form compounds. When the outermost orbital is NOT full, it will try and fill its orbital by combining with other atoms. To become stable, an atom will either GAIN, LOSE, or SHARE electrons. An atom will bond with another atom if the bond gives both atoms complete valence energy levels.

Two major types of bonds that can form compounds: IONIC BONDS COVALENT BONDS

IONIC BONDS DEFINITION: A bond that completely transfers electrons from one atom to another. Electrons are completely given up or taken in order for atoms to have a completely full outermost orbital. Remember- that’s when atoms are most happy and stable!

IONIC BONDS (cont.) 11 p+ 11 n0 17 p+ 17 n0 Na Cl

NaCl Na+1 Cl-1 IONIC BONDS (cont.) Happy! Happy! 11 p+ 11 n0 17 p+ + 10 e- 1+ Cl-1 17 p+ + 18 e- 1- Na+1

Ionic Bonds (cont.) When electrons are gained or lost, the elements take on a charge. The charge will be either positive or negative based on gaining or losing electrons. These charged elements are called IONS. http://www.visionlearning.com/library/flash_viewer.php?oid=1349&mid=55 http://www.youtube.com/watch?v=Ftw7a5ccubs&feature=related

COVALENT BONDS DEFINITION: A bond that shares electrons from one atom to another. Electrons are NOT completely given up or taken, BUT ARE SHARED. This allows for atoms to have a completely full outermost orbital.

COVALENT BONDS Example: H2O

Ionic & covalent bonding video More covalent bonds!

Chapter 2 – Properties of Water

Properties of Water Polar covalent bonds- e- are shared, however, electrons are pulled more towards the oxygen, due to the more protons (+ charges) in the nucleus. Water is POLAR due to this PULL, or uneven distribution of electrons.

Hydrogen bonds (weak bonds) Cohesion- attraction between molecules of the SAME substance (Ex. Water beads up due to the attraction between similar water molecules- “Surface tension” on penny) Adhesion- attraction between molecules of the DIFFERENT substances (Ex. Adhesives like glue, tape, etc.)

Acids/ Bases/ pH Scale Water can break apart into ions H2O H+ + OH- Water Hydrogen Hydroxide Ion Ion The pH scale measures the concentration of H+ ions in a solution.

Acids/Bases pH scale ranges from 0-14. Any reading BELOW 7 on the pH scale is an ACID. (HIGH concentration of H+ ions) Any reading ABOVE 7 on the pH scale is an BASE. (LOW concentration of H+ ions)

Acids (Acidic solutions) – lower the pH, the STRONGER the acid. Bases (ALKALINE solutions) – higher the pH, the STRONGER the base.

Buffers Any pH level near 7, is consider NEUTRAL. Buffers can be added to strong acids/bases to prevent strong changes in the pH levels. * Very important for maintaining blood pH in humans (HOMEOSTASIS)