Chapter 1: The Metric System The metric system offers simplicity and basic units. Physical QuantitySI basic unit Symbol LengthMeter m MassGram g TimeSecond s TemperatureKelvin K Celsius C VolumeLiter L Amount of substance mole mol

Chapter 2- The Chemical Basis of Life

I. Nature of Matter A. Elements 1. Matter: anything that occupies space and has mass 2. Element: is a pure substance that can not be broken down into other substances a. Example: Na = sodium Cl = Chlorine H = Hydrogen O = Oxygen

3. Compound: is a group of elements that are chemically joined together to create a new substance a. Example: NaCl = sodium chloride or table salt and H 2 O = water b. Compounds will have different physical and chemical properties than those of the single element.

4. There are 25 essential elements that are necessary for life. The 1 st 4 elements make up 96% of the matter in your body.  Oxygen = OCarbon = C  Hydrogen = HNitrogen = N  Calcium = CaPhosphorus = P Magnesium = Mg  Potassium = KSulfur = S

5. Trace Elements make up less than 0.01% of your body mass. They are very important for your health. a. Trace Elements include: Iron = Fe, Sodium = Na, Chlorine = Cl, Iodine = I, Copper = Cu, Fluorine = F, Manganese = Mn, Selenium = Se

6. Mnemonic Device for the 11 major elements of life:  Mg, Ca, Fe, S, H, O, P, I, N, C, K  Example: C. HOPKINS CaFe Mg  C. Hopkins café (is) mighty good.

B. Compounds 1. Most elements interact act with other elements to form compounds 2. When elements combine, they will be in a fixed ratio a. For example, a water molecule (H 2 O) always has 2 hydrogen atoms attached to 1 oxygen atom

C. Atoms 1. Each element consists of a single kind of atom and this atom is different than all other elements 2. Atom: smallest piece of matter 3. Made up of 3 subatomic particles: proton (+), neutron (no charge) and electron (-)

a. Protons i. Positive charge ii. Found in the nucleus( or center) of the atom iii. The # of protons in the atom determines the type of element. This number is called the atomic number. b. Neutrons i. Neutral/no charge ii. Found in the nucleus of the atom iii. Usually the #of protons = the #of neutrons iv. The atomic mass = # of neutrons + # of protons

. c. Electrons i. Negative charge ii. Located in the electron cloud outside the nucleus, always moving iii. Very small, very little mass iv. An atom with a net charge of zero, will have the same #of protons & electrons

D. Isotopes 1. All atoms of an element must have the same # of protons, but they can have a different #of neutrons. 2. An atom with more or less neutrons than protons is called an isotope.

3. Some isotopes are radioactive- meaning the nucleus decays or breaks down over time a. Radioactive isotopes are used in research and medicine b. We can track how an element moves through the body if it is radioactive. c. Radioactive isotopes are also used in carbon dating to determine the age of fossils and rocks found on earth.

4. Example:  Carbon- 12Carbon- 13Carbon- 14  6 protons6 protons6 proton  6 neutrons7 neutrons8 neutrons  6 electrons6 electrons6 electrons

E. Ionic Bonds 1. Forms when an atom transfers an electron to another atom 2. Example: NaCl 3. Ions are formed as a result of an ionic bond a. An ion is an atom that has a charge Cation = + charge Anion = - charge

F. Covalent bonds 1. Forms when 2 atoms share electrons 2. Example: H 2 O

G. Chemical Reactions 1. Occur when existing chemical bonds are broken and new ones are created to form a new substance 2. Some reactions release energy and some absorb energy 3. Reactants are on the left side of the arrow, products are on the right side of the arrow 4. Do not create or destroy matter, only rearrange

Warm-up 9/4/13 1. Why do all isotopes of an element have the same chemical properties? - b/c they all have the same # of protons and electrons 2. Water (H 2 O) and hydrogen peroxide (H 2 O 2 ) both consist of H and O atoms. Explain why they have different physical and chemical properties. - the 2 compounds have different properties b/c they contain different proportions of H and O atoms 3. How many mL are in 4 gallons? - 4 gal x L x 1000 mL = 15,140 mL 1 gal 1 L

II. Properties of Water A. The structure of H 2 O 1. 2 H atoms are joined to an O atom by a single covalent bond 2. H 2 O is a polar molecule, meaning the molecule has opposite ends with opposite charges a. This happens when the O pulls the electrons much more strongly than the H atom 3. H 2 0 molecules are attracted to each other by a very weak bond called a hydrogen bond

B. Water’s Life Supporting Properties 1. Cohesion & Adhesion a. Cohesion: the tendency of molecules of the same kind to stick together (pg. 41 Fig 2-7) b. Adhesion: the type of attraction that occurs between unlike molecules c. Help transport water from roots up to the leaves in a tree

2. Heat Capacity a. due to H bonding, water has the ability to resist temperature change b. helps to keep our body temperature stable 3. Low Density of Ice a. usually an element in the solid is more dense than the liquid state b. water is the opposite: the solid form is less dense than the liquid form (remember…ice floats)

4. Water’s Ability to Dissolve Other Substances a. solvent: the substance that does the dissolving (WATER) b. solute: the substance being dissolved (SALT) c. solution: the solute dissolved in the solvent (SALT WATER) d. aqueous solution has water as the solvent e. water is the main solvent in the body

C. Acids, Bases and pH 1. The pH scale a. describes how acidic or basic a substance is b. scale is from being very acidic, 14 being very basic c. Each pH unit represents a tenfold change in the concentration of H + ions d. Pure water and substances that have an equal amount of H + and OH - ions are said to the neutral with a pH of 7. e. Substances with a low pH have lots of H + ions and are considered to be acidic. f. Substances with a high pH have lots of OH - ions and are considered to be basic. H + = hydrogen ion OH - = hydroxide ion