The Chemistry of Life: Atoms and Molecules =

Pure substances that cannot be broken down into simpler chemical entities by ordinary chemical reactions. Elements Periodic Table 112 known elements

Major Elements Comprising the Biological Molecules of Living Things C arbonC arbon H ydrogenH ydrogen O xygenO xygen N itrogenN itrogen P hosphorusP hosphorus S ulfurS ulfur

Other Major Elements of Living Things Calcium (Ca)Calcium (Ca) Potassium (K)Potassium (K) Chlorine (Cl)Chlorine (Cl) Magnesium (Mg)Magnesium (Mg)

Some Important Trace Elements of Living Things Boron (B)Boron (B) Cobalt (Co)Cobalt (Co) Iron (Fe)Iron (Fe) Copper (Cu)Copper (Cu) Fluorine (F)Fluorine (F) Zinc (Zn)Zinc (Zn)

An element is composed of atoms (0.1-1 nm in diameter) Atom  cluster of small particles (proton, neutron, electron) Elements & Atoms

Subatomic Particles Protons (p + ) Neutrons (n o ) Electrons (e - )

Electron Shell Configurations of Atoms proton neutron electron hydrogen atom helium atom carbon atom 1p, 0n, 1e-2p, 2n, 2e- 6p, 6n, 6e-

atomic number: number of p; #p = #e- 2 He  2e- and 2p He

atomic mass (atomic wt.) : sum of masses of p+n He  2p + 2n, atomic mass = He He p + n e-

p = n = e- = Atomic number = Atomic mass = C Carbon Atom

C12C13C14 stablestable isotopeunstable- radioactive isotope Isotope atoms that differ in the number of neutrons 12 6 C 13 6 C 14 6 C C

Molecule Two or more atoms held together by chemical bonds OxygenO 2 NitrogenN 2 AmmoniaNH 3 Carbon DioxideCO 2 WaterH 2 O MethaneCH 4 GlucoseC 6 H 12 O 6

Compound Binding two or more different kinds of elements together NaCl CH 4 C 6 H 12 O 6

Ion An atom that has either gained or lost electrons such that it exhibits a net charge Na + Cl -

Sodium (Na) Atom 11 P + 12 N o

Sodium (Na + ) Ion 11 P + 12 N o +

Chlorine (Cl) Atom 17 P + 18 N o

Chloride (Cl - ) Ion 17 P + 18 N o _

Some Examples of Ions HydrogenH + PotassiumK + FluorideF - CalciumCa +2 MagnesiumMg +2

HydroxideOH - BicarbonateHCO 3 - NitrateNO 3 - PhosphatePO 4 -3 AmmoniumNH 4 + Acetate C 2 H 3 O 2 - Complex Ions

Bond Types Bond Types: Ionic Covalent Hydrogen

Ionic Bonds Transfer of electron 17 P + 18 N o 11 P + 12 N o

Covalent Bonding: Covalent Bonding: electron sharing O H H

C H H H H C H H H H

Hydrogen Bonding Between Water Molecules Covalent bond Hydrogen bond

Hydrogen Bonding Between Different Molecules

Examples of Organic Molecules

Properties of Water 1.High heat capacity-absorbs and releases large amounts of heat (land heats faster than water) 2.High heat of vaporization- sweat, cooling mechanism 3.Polarity solvent properties- universal solvent 4.Reactivity- hydrolysis and condensation (dehydration)

Polarity of Water Molecules

Chemical Reactions A  B reactant  product

Chemical Synthesis A + B  AB

Chemical Decomposition AB  A + B

Chemical Rearrangement AB + CD  AC + BD

H 2 O  OH - + H + OO HH H H + Water molecule [H 2 O] Hydroxyl ion [HO - ] Hydrogen ion [H + ] Decomposition of Water

Acids HCL  H + + Cl - Proton donor, i.e., they donate H + ions HCl is a strong acid with a pH 1-2

Bases Na + + OH -  NaOH NH 3 + H +  NH 4 OH - + H +  H 2 O HCO 3 +H +  H 2 CO 3 Proton acceptor, i.e., they take up H+ ions NaOH is a strong base ~pH 12

Neutralization HCl + NaOH  H 2 O + NaCl

Buffer- resists dramatic changes in pH; ex. tums, rolaids…buffers stomach acid

pH Scale Neutral7 Acidic0-6 Basic (alkaline)8-14 Type of Solution pH Value 0-14

Logarithmic scale pH Scale

Inquiry 1.How many neutrons in 7 N? 2.Of the following pH’s which is most acidic? The symbols K, Na, C, and S are: 4. Which of the following are elements? water; sugar; table salt; the atmosphere 5. Which of the following are pure substances? wine; seawater; blood; iron 14