Chapter 2- The chemical level of organization

chemistry

• Science that deals with the structure of matter

  – Including

  • Structure of atoms

  • Basic chemical building blocks

  • How atoms combine to form increasingly complex

  structures

matter

– Anything that takes up space and has mass

– Made up of atoms

• Atoms join together to form chemicals with different

characteristics

• Chemical characteristics determine physiology at

molecular and cellular levels

subatomic particles

– Protons

• Positive charge, 1 mass unit

– Neutrons

• Neutral, 1 mass unit

– Electrons

• Negative charge, low mass

atomic structure includes

• atomic number

• nucleus

• electron cloud

• electron shell

atomic number

number of protons

nucleus

contains protons and neutrons

electron cloud

spherical area that contains electons

electron shell

two- dimensional representation of electron cloud

what is the relation of the nucleus to the electron cloud

% of total body weight and significance for oxygen

65%

-a component of water and other compounds, gaseous form is essential for respiration

% of total body weight and significance for carbon

18.6%

-found in all organic molecules

% of total body weight and significance for hydrogen

9.7%

-a component of water and most other compounds in the body

% of total body weight and significance for nitrogen

3.2%

-found in proteins, nucleic acids, and other organic compounds

% of total body weight and significance for calcium

1.8%

-found in bones and teeth; important for membrane function, nerve impulses, muscle contraction, and blood clotting

% of total body weight and significance for phosphorus (P)

1.0%

-found in bones and teeth, nucleic acids, and high-energy compounds

% of total body weight and significance for potassium (K)

0.4%

-important for porper membrane function, nerve impulses, and muscle contraction

% of total body weight and significance for sodium (Na)

0.2%

-important for blood volume, membrane function, nerve impulses, and muscle contraction

% of total body weight and significance for Chlorine (Cl)

0.2%

-important for blood volume, membrane function, nerve impulses, and water absorbtion

% of total body weight and significance for magnesium (Mg)

0.06%

-a cofactor for many enzymes

% of total body weight and significance for sulfur (S)

0.04%

-found in many proteins

% of total body weight and significance for iron (Fe)

0.007%

-essential for oxygen transport and energy capture

% of total body weight and significance for iodine (I)

0.0002%

-a component for hormone of the thyroid gland

trace elements and significance

some fucntion as cofactors; the functions of many trace elements are poorly understood

typical hydrogen nucleus, deuterium nucleus, tritium nucleus

element

is a pure substance composed of atoms of

one kind

what is an atomic number and what does it determine

(number of protons) in an atom

determines its chemical properties

isotopes

are version of elements based on mass number

mass number

number of protons plus the number of neutrons

radioisotopes have

radioactive nuclei

decay rate is

expressed as half-life

atomic weight

average of the different atomic masses and proportions of different isotopes

mole (mol)

has a weight in grams equal to the atomic weight of the element

what does electron in the elctron cloud determine

the reactivity of an atom

what does an electron cloud contain

shells, or energy levels, that can hold a limited number of electrons

• Lower shells fill first

• Outermost shell is the valence shell, and it determines bonding

how many electrons can the first energy level hold

2 electrons max

how many electrons can the second and third level hold

8 electrons max

what does chemical bonds form

molecules and compounds

molecule

two or more atoms joined by strong bonds

compounds

two or more atoms of different elements joined by strong or weak bonds

molecule and compound relation

Not all molecules are compounds and not all compounds consist of molecules

molecular weight of a molecule or compound is

the sum of the atomic weights of its atoms

chemical notation of atoms

molecules in chemical notation

reactants and product in chemical notation

ions with chemical notations

chemical bonds involve

sharing, gaining, and losing electrons

three major types of chemical bonds

1. Ionic bonds

2. Covalent bonds

3. Hydrogen bonds

ionic bonds

– An ion is an atom with an electric charge

– One atom—the electron donor—loses one or more

electrons and becomes a cation

– Another atom—the electron acceptor—gains those

same electrons and becomes an anion

– Ionic bonds are attractions between cations (positive

ions) and anions (negative ions)

how does the formation of an ionic bond happen

1. formation of ions- a sodium atom gives up an election to chlorine

2. attraction between opposite charges - the sodium ion has a positive charge and chloride ion has a negative charge, they are attracted to one another

3. formation of an ionic compound- the association of sodium and chloride ions forms the ionic compound

covalent bonds

strong bonds involving shared electrons

• One electron is donated by each atom to make the

pair of electrons

• Sharing one pair of electrons is a single covalent

bond

• Sharing two pairs of electrons is a double covalent

bond

• Sharing three pairs of electrons is a triple covalent

bond

nonpolar covalent bonds

Equal sharing of electrons between atoms that have equal pull on the electrons

polar covalent bonds

• Unequal sharing of electrons because one atom has a disproportionately strong pull on the electrons

• Form polar molecules—like water

hydrogen bonds

– Weak polar bonds between adjacent molecules based on electrical attractions

– Involve attractions between a slight positive charge and a slight negative charge

– Hydrogen bonds between H2O molecules cause surface tension

states of matter

• solid

• liquid

• gas

solid

constant volume and shape

liquid

constant volume but changes shape

gas

changes volume and shape

chemical reaction

either new bonds are formed or existing bonds are broken

reactants

materials going into reaction

product

materials coming out of a reaction

metabolism

all of the reaction that are occurring at one time

energy

the capacity to do work

work

movement of an object or change in matter

kinetic energy

energy of motion

potential energy

stored energy

chemical energy

potential energy stored in chemical bonds

types of chemical reaction

1. Decomposition

2. Synthesis

3. Exchange

4. Reversible

decomposition reaction (catabolism)

– Breaks chemical bonds

– AB → A + B

– Hydrolysis reaction AB + H2O → AH + BOH

synthesis reaction (anabolism)

– Forms chemical bonds

– A + B → AB

– Dehydration synthesis (condensation) reaction

AH + BOH → AB + H2O

exchange reaction

– Involves decomposition first, then synthesis

– AB + CD → AD + CB

reversible reactions

– A + B ↔ AB

– At equilibrium, the amounts of chemicals do not change even though the reactions are still occurring

• Reversible reactions seek equilibrium, balancing opposing reaction rates

• When reactants are added or removed, reaction rates adjust to reach a new equilibrium

are biochemical reactions in cells occurring spontaneously or nonspontaneously?

do not occur spontaneously

Activation energy

• it is the amount of energy needed to start a reaction

• Enzymes are protein catalysts that lower the activation energy of reactions

exergonic reactions

release energy

endergonic reactions

absorb energy

nutrients

essential molecules obtained from food

metabolites

molecules made or broken down in the body

inorganic compounds

carbon dioxide, oxygen, water, and inorganic acids, bases, and salts

organic compounds

– Molecules containing carbon and hydrogen

– Carbohydrates, proteins, lipids, and nucleic acids

water (H2O)

– Accounts for up to two-thirds of total body weight

– Produces solutions—uniform mixtures of two or more substances

• A solution consists of a solvent, or liquid, and

solutes

• Solutes are the dissolved substances

universal solvent of water

many molecules are water soluble

reactivity of water

water serves as a reactant in some reaction

high heat capacity

heat capacity is the heat required to raise the temperature of a unit mass of a substance 1 degrees C

lubrication

to moisten and reduce friction

properties of aqueous solutions

– Water is a polar molecule

– Many inorganic compounds split into smaller molecules via dissociation in water

– Ionization is dissociation into ions

– Polar water molecules form hydration spheres around ions and small polar molecules that keep them in solution

ions released

electrolytes

– inorganic ions that conduct electricity in solution

– Electrolyte imbalance seriously disturbs vital body functions

hydrophilic

• hydro- = water, philos = loving

• Includes ions and polar molecules

• Interact with water

hydrophobic

• phobos = fear

• Includes nonpolar molecules, fats, and oils

• Do not interact with water

colloid

• A solution containing dispersed proteins or other large molecules

• Example: blood plasma

suspenion

• Contains large particles that settle out of solution

• Example: whole blood

pH

– The negative logarithm of the hydrogen ion concentration of a solution in moles per liter

Neutral pH

– A balance of H+ and OH–

– Pure water = 7.0

Acidic pH

(lower than 7.0)

– High H+ concentration

– Low OH– concentration

Basic

(or alkaline) pH (higher than 7.0)

– Low H+ concentration

– High OH– concentration

pH of human body

– Ranges from 7.35 to 7.45

pH scale

– Has an inverse relationship with H+ concentration

• More H+ ions means lower pH, fewer H+ ions means higher pH

acid

(proton donor)

– A solute that adds hydrogen ions to a solution

– Strong acids dissociate completely in solution

base

(proton acceptor)

– A solute that removes hydrogen ions from a solution

– Strong bases dissociate completely in solution

weak acids and weak bases

– Fail to dissociate completely

– Help to balance the pH