Standard II Objective 1

A. List the major chemicals in cells (i.e. Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur, and other trace elements)

Atoms  Atoms make up matter  Structure of an atom  Proton (+)  Nucleus ( )  Electron (-)

 BrainPOP - Atomic Models

Elements  An element is a pure substance that cannot be broken down into other substances.

Isotopes  Atoms of the same element that have different numbers of neutrons.  Radioactive isotopes – changing the number of neutrons can affect the stability of the nucleus, in some cases causing the nucleus to break apart.  Carbon-14 is radioactive and found in all living things. We know the half life (180,701,003,776 seconds) and are able to calculate the age of objects due to the remaining levels of carbon -14 in the sample.

 BrainPOP - Isotopes

 Have you ever heard about medical tests that require the use of radioisotopes? Which test? What isotope?

Compounds  A compound is a pure substance formed when two or more elements combine.

Ionic bonding Some atoms tend to donate or accept electrons to empty of fill the outer energy to become stable. An atom that has lost or gained an electron becomes an ion. An ionic bond is when two oppositely charged atoms, or group of atoms, are electrically attracted.

 Animation - Ionic bonding

Covalent bonding A covalent bond is formed when electrons are shared A molecule is a compound in which the atoms are held together by covalent bonds.

 How do the electrons in the covalent bond know which atoms they belong to?

Electrons are not specific to atoms, they do not “belong” to any particular atom. All electrons are the same and can be transferred from one atom to another.

Van der Walls forces  When molecules come close together, the attractive forces between these positive and negative regions pull on the molecules and hold them together.

 Water jar demonstration

Bond strengths

Carbon edia/commons/5/5b/Carbon_Le wis_Structure_PNG.png

Hydrogen asic/lewis/LS%20001.png

Nitrogen nqaX64TgMLU/UKHSGafUy8I/AAAAAA AAACM/7VWjHQ1GFLY/s1600/nitrogen lewis.jpg

Oxygen emistry/bonding/images/Oxygen- Dot-Structure.jpg

Phosphorus Brr-2_P6uM/s1600/phosphorous-bohr.gif content/uploads/2015/04/Phosphorus_Tile-300x300.png ads/2/8/3/4/ / _orig.png

Sulfur on_files/Sulphur_1.jpg lewis-structure.jpg with-sulfur.png AAinI/AAAAAAAAAIo/vwK_NLBcibA/s1600/disul fide_bond_formation.gif

Other trace elements Trace elements are present at low levels in organisms and make up just 0.5% of living cells.  However, living things would not be able to survive without trace elements.  Trace elements include iron, iodine, manganese, molybdenum, selenium, silicon, tin, vanadium, boron, chromium, cobalt, copper and fluorine.  Iron is found in red blood cells and helps to carry oxygen in the blood stream.  Iodine is important for making different forms of thyroid hormone, which regulates growth and energy levels in humans. Many of the trace elements are required by enzymes in order to make chemical reactions happen.

Take away 1.C, H, N, O, P, S, are the major elements found in living things.

Honors curriculum 1.Basic bonding behavior (ionic, covalent, hydrogen) and their relative strengths.

On a separate piece of paper answer the following questions; 1.Sodium has 11 protons and 11 neutrons in its nucleus. Draw a sodium atom. Be sure to label the particles. 2.Explain why carbon monoxide (CO) is or is not an atom. 3.Are all compounds molecules? Why or why not? 4.Compare van der Waals forces, ionic bonds, and covalent bonds. 5.Explain how the number of electrons in an energy level affects bond formation. 6.Name four important biogeochemical processes that cycle nutrients. 7.Beryllium has four protons in its nucleus. How many neutrons are in beryllium-9? Explain how you calculated your answer. 8.Describe how phosphorus moves through biotic and abiotic parts of an ecosystem.