The Chemical Level of Organization

Chapter 2

Chemistry Review Matter – anything that occupies space and has

weight

Atom – smallest stable unit of matter Protons – positive electrical charge Neutrons - uncharged Electrons – negative electrical charge

Atomic Number Number of protons in the nucleus

Atomic Weight (Mass) Approx. number of protons + neutrons

Chemistry Review Atom with a full outer electron shell is stable

helium, neon, argon, krypton, xenon, and radon

Atoms without full shell can achieve stability by sharing, gaining, or losing electrons through chemical reactions Many of these reactions produce molecules Molecules called compounds contain atoms of

more than one element

What are valence electrons

Chemistry Review Element

Consists of entirely one type of atom

Many found in the body Oxygen

65% Carbon

18.6% Hydrogen 9.7% Nitrogen

3.2% Calcium

1.8% Phosphorus 1% Potassium <1% Chlorine, Magnesium,

Sodium, Sulfur, Iron, Iodine

Compound Molecules containing

more than one type of atom

Water - H2O Salt - NaCl Methane - CH4

Chemistry Review Compounds have properties that can be very

different from their components. A mixture of hydrogen and oxygen is a flammable

gas Combining hydrogen and oxygen produces water

Bonding Ionic Bonds Covalent Bonds

Single Double Polar

Hydrogen Bonds

Ionic Bonding Ions are charged atoms – having lost or

gained electron(s) Atoms are held together by the attraction

between positive and negative charges

Ionic Bond - Sodium Chloride NaCl

Covalent Bonding Atoms share electrons to complete outer

electron shells Resulting bond is called a covalent bond

Ethane

Hydrogen chloride

Single covalent bond Sharing of one pair of electrons

Double Covalent Bond Sharing of two pairs of electrons

Polar Covalent An unequal sharing of electrons In water:

The oxygen atom has a stronger attraction for the electrons – the electrons spend more time there – so there is a negative charge

The hydrogen side is positively charged

Hydrogen Bond Within molecules some hydrogen atoms are

positively charged and some are negatively charged

Hydrogen bonding does not form molecules but can alter shapes or pull molecules together

Acids Bases

A solute Releases hydrogen

ions

HCl H+ + Cl-

A solute Removes hydrogen

ions

NaOH Na+ + OH-

Hydroxide ions have an affinity for hydrogen ions

OH- + H+ H20

pH pH is the concentration of hydrogen ions in a

solution

pH range is 0-14, pure water is 7 Below 7 is acidic…hydrogen ions outnumber

hydroxide ions Above 7 is basic….hydroxide ions outnumbers

hydrogen ions

In excessive amounts H+ will disrupt cell and tissue function

Blood pH ranges from 7.35-7.45 Below 7 can produce a coma Over 7.8 causes uncontrolled, sustained muscular

contractions

Buffers Compounds responsible for stabilizing pH

Remove or replace Hydrogen ions Antacids

Alka-Seltzer, Rolaids, Tums Tie up excess Hydrogen ions in the stomach

Extracellular - Sodium bicarbonate, ammonia Intracellular – proteins, phosphate

H2O + CO2 H2CO3 H+ + HCO3-

carbonic acid (H2CO3) - bicarbonate (HCO3-)

Nutrients and Metabolites Nutrients are essential elements and

molecules absorbed from foods

Metabolites are all molecules synthesized or broken down by chemical reactions in our body

Nutrients and metabolites can be categorized as inorganic or organic

Inorganic Compounds Generally do not contain carbon

Carbon Dioxide, Oxygen

Water

Inorganic Acids and Bases

Salts