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.

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

2-1 The Nature of Matter

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

ELEMENTS A pure chemical that is made up of only one type of atom is an ELEMENT. Every element has specific name, symbol, and DIFFERENT ATOMIC NUMBER. The atomic number is ALWAYS the # of Protons in the atom. (Argon?? _______)

Elements and the Periodic Table Most elements on the Periodic Table are found in nature, some were formed in a laboratory by scientists. The atomic # is also usually the same # of neutrons and electrons. (EXCEPTIONS!) Example: Atomic Mass = Sum of protons + neutrons (Argon ?? ____________________________)

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 Chlorine * Flip to the back of your periodic table and finish the practice questions!

Remember there are EXCEPTIONS! The atomic number of an element NEVER changes! IT IS ALWAYS THE # OF PROTONS IN THE NUCLEUS! The NEUTRONS can vary from one atom of that element to the next. Atoms of the same element, same number of protons, but different # of neutrons are called isotopes. Examples: 13C 14C All are Carbon atoms, just with different atomic MASSES! (same atomic #)

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+ 12 n0 17 p+ 18 n0 Na Cl

NaCl Na+1 Cl-1 IONIC BONDS (cont.) Happy! Happy! 11 p+ 12 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. Chemical Bonding Animations Chemical reaction NaCl – Animation video

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

More covalent bonds! Ionic & covalent bonding video Ionic vs. covalent Animation More covalent bonds!

2-2 Properties of Water Animation Tutorial

Properties of Water Unique due to its special chemical bonding and structure Universal Solvent – can dissolve most other substances Solute, Solvent, Solution Why?? Polar Covalent Bonds Hydrogen Bonds

Polar covalent bonds In water molecules, 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 sharing of electrons.

Water’s polar covalent bonds

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

Capillary Action Movement of water through a ‘tube’, by water molecules pulling on other water molecules (cohesion) and an attraction of water to the sides of tube (adhesion) Capillary Action in Plants (see Class Zone animation- Movement through Plants; Ch. 31)

Remember C.A.S.H! Surface Tension Cohesion and Adhesion creates Surface tension through Hydrogen bonding Lizard that “walks on water”

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)

pH test strips

pH Scale Acids (Acidic solutions) – the 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)

IF YOU KNOW YOUR CHEMISTRY, you will laugh…..

Ions and Ionic Bonding

WATER!

pH