Bpk 105 Mod 2

The Chemistry of Life

Atom

is the smallest particle of an element that has the chemical characteristics of that element

• ex: element carbon only consists on carbon atoms

what do the characteristics of matter result from?

the structure, organization, and behaviour of atoms (subatomic charge)

what are the 3 major types of subatomic particles are there?

• neutrons = no electrical charge

• protons = one positive charge

• electrons = one negative charge

define “electrical charge.” What are the 2 types?

the tendency of particles to be attracted to each other or repulsed from each other

• can be + or -

where are electrons found?

in the electron cloud (outside the nucleus)

the nucleus accounts for ____% of an atom’s mass but only one-tenth-trillion of its volume

99.97%

the # of protons in each atom is called the ___ because why?

atomic number

• the # of electrons & protons in an atom are =

• atomic # is also the # of electrons

do all prot, nut, and elec have the same mass?

no

• prot and nut have same mass

• elec have very little mass

define the mass number of an element - give an example

is determined by adding the # of protons & neutrons one each atoms

• ex: Carbon has 6 prot & 6 neut = mass number 12

the atomic number of fluorine = 9

the mass number is 19

what is the # of pro, neut, and elec in an atom of fluorine?

prot = 9

neut = 10

elec = 9

define isotopes

are two or more forms of the same element that have the same # of prot & elec but diff # of neutrons

• most familiar = radioactive → used in nuclear medicine

• PET scans use radioactive isotopes to examine blood flow to organs to detect cancer

Chemical bond

association btwn two atoms formed when the outermost electrons are transferred or shared btwn atoms

explain how many electrons can be held at each electron shell

• 2

• 8

• 8

• 18

what’s an octet

if an atom’s valence shell is not at its max → it will form bonds with other atoms to achieve a full valence shell = octet

what’s the octet rule?

the tendency of atoms to combine with other atoms until each has 8 electrons in its valence shell (hydrogen will have 2 electrons)

what are the 2 ways atoms achieve an octet?

1) by transferring electrons btwn atoms

2) by sharing electrons btwn atoms

whether an atom transfers or shares electrons depends on what?

electronegativities of the 2 atoms

• if electronegativity is very diff = atoms tend to transfer electrons from one atom to the other

• if electronegativity is very similar = atoms will share electrons

define electronegativity + what is strong vs weak

the ability of the atom’s nucleic to pull electrons two it

• atoms w strong electronegativity = 6 or 7 electrons in valence shell (very close to achieving an octet)

• atoms w weak electronegativity = 1 or 2 electrons in valence shell (further away from achieving an octet)

ionic bond

when the electronegativity is different btwn 2 atoms, one atom can donate electrons to or gain electrons form other atoms

• when this happens → # of prot and elec are no longer equal

• charged particle = an ion

• if an atom loses an elec = one more prot than elec = positively charged → vice versa

• electrons are transferred btwn 2 atoms creating oppositely charged ions (1 + and 1 -)

what’s a common example of an ionic bond

Na+Cl-

sodium chloride

if an iron (Fe) atom loses 3 electrons, what is the charge of the resulting ion? Write the symbol for this ion

Fe3+

covalent bond

forms when atoms share one or more electrons

why do covalent bonds share electrons? What does this result in?

• sharing occurs because atoms have similar electronegativities

• resulting combination of atoms = a molecule

molecule

a molecule is formed when two or more atoms chemically combine to form a structure that behaves as an independent unit

• share atoms in covalent bonds

• can be same type of atoms or multiple diff types

what are the subscripts of atoms

denote the quantity of each type of atom (or ion)

• ex: glucose → C6H12O6

• 6 carbon, 12 hydrogen, 6 oxygen

what are intermolecular forces

weak electrostatic attractions that exist btwn oppositely charged parts of mlcs, or btwn ions and mlcs

• there is no exchange of electrons in intermolecular forces

• they are much weaker than the forces producing chemical bonds

• include hydrogen bonds + properties of solubility & dissociation

differentiate nonpolar covalent, polar covalent, ionic

nonpolar covalent:

• equal sharing of electrons btwn atoms = even charge distribution among atoms in the mlc

polar covalent:

• unequal sharing of electrons btwn atoms = a slightly pos. charge on one side of mlc and a slightly neg. charge on the other side of mlc

ionic:

• complete electron transfer = one pos charged ion & one neg charged ion

what’s a nonpolar molecule?

a molecule formed by nonpolar covalent bonds where there is equal sharing of electrons btwn atoms of the mlc

• a nonpolar mlc carries a neutral charge

what’s a compound?

is a substance resulting from the chemical combination two or more diff types of atoms

• water is a mlc that is also a compound = combination of 2 diff types of atoms (H & O)

when do hydrogen bonds form? What are they important for?

• H bonds form when the positive H+ of one polar mlc is attracted to the negative oxygen, nitrogen, or fluorine

• H bonds act as a velcro that holds water mlcs tgth → giving water its unique properties like surface tension and heat capacity

Important:

• velcro effect is crucial in biological structures like proteins & DNA → stabilizing their complex shapes

hydrogen bonds form ___ within the same mlc

intramolecular bonds

what are intramolecular bonds?

• intramolecular H bonds form complex structures of proteins & nucleic acids & help stabilize their intricate three-dimensional shapes

• they ensure proteins & nucleic acids maintain functionality

• if disrupted → structures collapse =. denaturing loss of function

what is dissociation

• when ionic compounds dissolve in water = their ions dissociate (separate form each other

• happens bc the positively charged ions are attracted to the negative ends of the water mlcs & negatively charged ions are attracted to the positive ends of the water water mlcs

what’s an example of dissociation? what are the dissociated ions called?

when NaCl dissociates in water:

• Na+ and Cl- separate & water mlcs surround and isolate ions keeping them in solution

dissociated ions:

• electrolytes → have capacity to conduct electrical current (the flow of charged particles)

what does an electrocardiogram (ECG) have to do with electrolytes?

• ECG is a recording of electrical currents produced by the heart

• these currents can be detected by electrodes on the surface of the body bc the ions in the body fluids conduct electrical signals

do molecules stay intact when in water?

when mlcs dissolve in water they remain intact even tho surrounded by water mlcs

• ex: glucose mlcs stay intact when in water

what are electrolytes?

when ionic compounds dissociate in water → their separated ions are called electrolytes

• have capacity to conduct electrical current (the flow of charged particles)

what’s a chemical reaction

the formation or breaking of chemical bonds btwn atoms, ions, mlcs, or compounds

chemical rxns can be classified as what 3 types of rxns?

1) Synthesis rxn

2) Decomposition rxn

3) Exchange rxn

what’s a Synthesis Reaction? Whats the formula?

• when 2 or more reactants combine to form a larger, more complex product

• A + B → AB

what is ATP (Adenosine Triphosphate)

• results from a synthesis rxn

  • A = adenosine

  • T = tri- (three)

  • P = phosphate

• ATP is synthesized when ADP (2 phosphate groups) combines with another phosphate group

what is the phosphate group called that reacts with ADP to synthesize ATP

Pi → “i” indicates that the phosphate group is associated w an inorganic substance

what are all synthesis reactions that occur in the body collectively referred to as?

Anabolism

growth, maintenance, and repair of the body couldn’t take place without what type of reaction?

anabolism reactions

What are dehydration reactions?

when water is a product in a synthesis reaction

(“dehydration synthesis” is when water is taken out of a mlc to synthesize 2 other mlcs → therefore, water is a product)

What are decomposition reactions? What is the formula?

• reactants are broken down into smaller, less complex products

• is the reverse of a synthesis rxn

• AB → A + B

explain how the breakdown of food is an example of a decomposition rxn

food mlcs are broken down into basic building blocks + the breakdown of ATP into ADP + a phosphate group

• A-P-P-P (ATP) → A-P-P + Pi (ADP + Pi)

what are decomposition reactions in the body collectively called?

catabolism

what are hydrolysis reactions?

• a type of decomposition rxn

• the addition of a water mlc to break down foods into individual nutrients

• the opposite of dehydration synthesis

whats an example of where hydrolysis occurs during food digestion?

in the intestine & within cells

• breakdown of lipid stores

• breakdown of foreign matter & microorganisms in certain blood cells protect the body

what are all anabolic and catabolic reactions in the body collectively defined as?

metabolism

• anabolic (synthesis) - ex: dehydration synthesis (combining)

• catabolic (decomposition - ex: hydrolysis (breaking down)

what’s an exchange reaction? what’s the formula?

is the combination a decomposition rxn and a synthesis rxn

• breaking down & combining

• AB + CD → AC + BD

what’s an example of an exchange reaction?

hydrochloric acid (HCl) with sodium hydroxide (NaOH) to form table salt (NaCl)& water (H2O)

• HCl + NaOH → NaCl + H2O

what are reversible reactions?

• when the rxn can run int eh opposite direction → products are converted back to the original reactants

what is equilibrium in a reaction?

when the rate of product formation is equal to the rate of reactant formation

• at Eq → the amt of reactants relative to the amt of products remain the same

• ex: in a FB game → same # of players on bench will exchange w same # of players on the field

what’s an important example of a reversible rxn in the human body?

when carbon dioxide (CO2) and water (H2O) form hydrogen ions (H+) and bicarbonate (HCO3)

• rxn indicated by 2 arrows pointing in both directions

• CO2 + H2O <=> H + HCO3

why is maintaining a constant level of H+ in body fluids necessary?

fir the nervous system to function properly

• level can be maintained by controlling blood CO2 levels

• ex: slowing respiration rate causes CO2 levels to increased = increase H+ levels

if respiration rate increases, CO2 is removed from the blood → what effect does this have on blood H+ levels?

• decrease in CO2 leads to a reduction of H+ concentration

• CO2 and H+ are directly related to the blood’s buffering system

• results in a raise in pH (less acidic blood)

what is energy? Define “work”

energy is the capacity to work

• work = the mvmnt of matter into motion

• energy is the ability to put matter into motion

what’s potential energy VS kinetic energy? Give an example

Potential energy:

• stored energy

Kinetic energy:

• energy caused by mvmnt of an object & is the form of energy that actually does work

Example:

• a ball held at arms length above the floor has potential energy (no energy is expended as long as ball doesnt move)

• if ball is released and falls twd the floor = kinetic energy

• when potential energy is released it becomes kinetic energy → thus doing work

what are reactants

the substances that enter into a chemical reaction

products

the substance that result from a chemical reaction

explain the law of conservation of energy

• total energy of the universe is constant

• energy is neither created or destroyed BUT can take on diff forms

name the 5 diff forms that potential and kinetic energy exist in

1) mechanical energy

2) chemical energy

3) heat energy

4) electrical energy

5) electromagnetic (radiant) energy

what is mechanical energy

is energy resulting form the position or mvmnt of objects

• many of the activities of the human body (moving a limb, breathing, circulating blood) involve mechanical energy

what is chemical energy?

a form of potential energy stored within chemical bonds of a substance

• in any chemical rxn → pot. energy within chemical bonds of reactants can be compared w the pot. energy in the chemical bonds of the products

• if pot. energy is less than in the products → energy input is needed for rxn to occur

  • ex: synthesis of ADP into ATP = ADP + Pi + energy (from food mlcs) → ATP (more pot energy than reactants)

what is energy used for within body processes?

• majority of energy released is used by cells to synthesize or transport certain mlcs in the cell or to do mechanical work (contracting muscles)

• some energy from the breakdown of ATP is released as heat

• human body temp is maintained by heat produced as a by-product of chemical rxns (metabolism)

why does body temp increase during exercise?

• during exercise → muscles convert potential energy into kinetic energy (like a car engine turning fuel into motion)

• produces heat as a by-product

• as muscles work harder → more heat is generated = raising body temp

• to maintain homeostasis, body much release excess heat to prevent overheating (sweating)

whats a catalyst? what is an enzyme? what is the suffix for most enzymes?

a substance that increases the rate of a chemical rxn without itself being permanently changed or depleted

• many of chemical rxns in body require enzymes (a protein catalyst)

• suffix for enzymes = “-ase”

how do enzymes work?

• increase the rate of chemical rxns by lowering the activation energy which is necessary to start a chemical rxn

• most chemical rxns in the body have high activation energies (EA) which are decreased by enzymes

explain why enzymes help reactions proceed

• activation energy (EA) is requited to initiate chemical rxns

• without an enzyme → a chemical rxn can proceed but it needs more energy input (has higher EA)

• Enzymes lower the required EA = making it easier for the rxn to proceed

how do atomic particles relate to X-ray imaging?

• Protons, neutrons, and electrons define an atom's chemical properties and facilitate clinical imaging

• X-rays, produced by high-energy electrons striking a positive electrode, penetrate tissues differently based on density

• Dense tissues appear white on x-ray films, while less dense tissues appear dark

• Radiopaque substances enhance imaging by absorbing x-rays, revealing organ outlines and abnormalities

T/F - the greater [ ] of reactants the greater the rate at which a given chemical rxn proceeds

true

• if there is a greater [ ] - larger amnt of reactants → there is a higher chance that they will come in contact w each other (bump into each other) and react

• ex: if there is less O2 within a cell, it can impair a cell function or result in death (less chemical rxns taking place due to decreased [ ] of reactants (O2)

whats an acid

• a proton donor

• a hydrogen atom without its electron = a proton

• any substance that releases hydrogen ions (H+) in water is an acid

• ex: hydrochloric acid (HCl) in the stomach forms H+ and chloride (Cl-) ions

• H+

what is a base

• a proton acceptor

• ex: sodium hydroxide (NaOH) forms sodium ions (Na+) and hydroxide ions (OH-)

• it is a base bc the OH- isa proton acceptor that binds w H+ to form water

• OH-

whats a pH scale?

• reference to t

buffers

carbohydrate

lipid

proteins

nucleic acids

chemistry

the scientific study of the atomic composition of substances & the rxns they undergo

Explain: Matter, Mass, and Weight

Matter:

• anything that occupies space & has mass

Mass:

• is the amount of matter in an object

Weight:

• is the gravitational force acting on an object of a given mass

The difference btwn mass & weight can be illustrated by considering an astronaut. How would an astronaut’s mass & weight in outer space compare with that astronauts mass & weight on the earth’s surface?

mass: stays the same in outer space & on Earth

weight: is much less in outer space because there is little to no gravity (weight is the gravitational force acting on an object of a given mass)

what’s the international unit for mass?

kilogram (kg)

an element

is the simplest type of matter having unique properties (periodic table)

• 96% of body’s weight results from elements such as O2, CO2, H+, and N+2 (nitrogen)

give an example of how elements play an important role in the human body

• calcium helps form bones

• sodium ions are essential for neuronal activity

T/F - some elements are present in only trace amounts but are still essential for life

true