Chapter 2 Flashcards
all matter is composed of ___?
ATOMS!
why does chemistry matter in biology?
the reactions in cells involve atoms and chemical bonds joining together or breaking apart
what charge do electrons have?
negative
what charge do protons have?
positive
what charge do neutrons have?
no charge, they are neutral
what subatomic particles are located in the nucleus of the atom?
protons and neutrons
what subatomic particles orbit the nucleus?
electrons
what makes different atoms different?
the number of electrons and neutrons
what is an element?
a substance whose atoms all have the same number of protons
what are isotopes?
atoms of the same element that have different atomic mass numbers due to different number of neutrons
what is a way that the characteristics of atoms can change?
radioactive decay
what are neutral atoms?
atoms that have an overall neutral charge
what is the overall goal of nature?
equilibrium
why does equilibrium matter?
atoms want to be neutral, meaning their electrons want to be paired
what are ions?
atoms that have gained or lost an electron and have a changed overall net charge
what are cations?
positively charged ions that have lost an electron
Plussy Cat’s are a good, positive thing :0
what are anions?
negatively charged ions that have gained an electron
An(T)ions are bad and negative because they bite you!
where in the atom does chemical bonding take place?
in the outermost electron orbital
what type of energy do electrons possess?
potential energy
where is the potential energy of an electron the strongest?
in the outermost orbital
like a ball at the top of a hill
where is the potential energy of an electron the weakest?
closest to the nucleus
like the ball at the bottom of a hill
what two things can happen to an electron during bonding?
oxidation or reduction
what is oxidation? (OiL)
Oxidation is the Loss of an electron by an atom during bonding, resulting in a cation
what is reduction? (RiG)
Reduction is the Gain of an electron by an atom during bonding, resulting in an anion
what is it called when atoms engage in and OiLRiG reaction?
a Redox reaction!
what are valence electrons?
electrons in the outermost energy shell of an atom
what’s so special about hydrogen?
it only has a single electron, and only one energy shell, so it’s very reactive, because that electron is lonely :(
what’s special about the Group 18 elements?
all their valence electrons are paired, so they are inert and never form bonds
what’s special about CARBON and silicon?
they have 4 unpaired valence electrons, so they can form bonds with up to four other atoms
do atoms like their energy levels empty or full?
FULL
how do atoms fill their empty outer energy levels?
by bonding with another atom
are atoms with full energy levels more or less reactive than atoms with unfilled energy levels
MORE REACTIVE, every electron wants a friend!
how many naturally occurring elements are there?
90
how many elements are found in living organisms in substantial amounts?
12
how many elements make up 96.3% of living things, and what are they?
4: CHON Carbon Hydrogen Oxygen Nitrogen
what elements MUST organic compounds contain?
carbon, hydrogen, and oxygen
what compound makes up most of our cells?
water
is water (H20) an organic compound?
NO
why isn’t water an organic compound?
it does not contain Carbon
what are molecules?
groups of atoms held together in a stable association
ex. hydrogen gas, H2
what are compounds?
molecules that contain more than one type of elements
all compounds are molecules, but not all molecules are compounds
what holds atoms together?
chemical bonds
name the three kinds of chemical bonds
ionic, covalent, and hydrogen bonds
how are ionic bonds formed?
by the attraction of oppositely charged ions (cations and anions)
list an example of an ionic bond
the bond between Sodium (Na) and Chlorine (Cl) to form NaCl
which is the electronegative element in NaCl?
Chlorine, both have one unpaired electron, but Chlorine is electron greedy and tries to steal Sodium’s unpaired electron for itself
what happens to the unpaired electron when Chlorine tries to steal it from Sodium?
Sodium is not pleased, and clings to Chlorine to try to get its electron back, thus the ionic bond is formed
what is the cation in NaCl?
Sodium, its electron is stolen :(, which makes it positive :)
what is the anion in NaCl?
Chlorine, our mean electron thief >:(
are ionic bonds strong?
no, they’re pretty weak
how are covalent bonds formed?
electron sharing
how many levels of bond strength are covalent bonds capable of?
3, and strength increases as the number of bonds increases
give an example of a single covalent bond
hydrogen gas, has one electron available for bonding
give an example of a double covalent bond
oxygen gas, has two electrons available for bonding
give an example of a triple covalent bond
nitrogen gas, has three electrons available for bonding
what is electronegativity?
electron greediness
why is electronegativity important in biology?
oxygen is VERY electronegative and forms MANY bonds
what are nonpolar covalent bonds?
covalent bonds where electrons are shared equally between interacting atoms
what are polar covalent bonds?
covalent bonds where electrons are NOT equally distributed around the nuclei of interacting atoms
@oxygen
what gives water its polarity?
the polar covalent bonds between oxygen and hydrogen
what happens when polar and nonpolar substances interact?
they repel each other, and form droplets, called micelles
chemical reactions involve ____?
chemical bonds between atoms
whether a chemical reaction occurs is influenced by _____?
how many unpaired electrons are present
how are chemical equations written?
reactants first, followed by the products
can chemical reactions be reversed?
yes, and they often are, especially in biology!
what kinds of chemical reactions do cells use?
reversible chemical reactions!
all living organisms are dependent on ____?
WATER!
what is the structure of water?
polar covalent bonds between oxygen and hydrogen
what is the most important property of water?
its ability to form hydrogen bonds
what are hydrogen bonds?
when two molecules of water interact and join together due to oxygen’s electronegativity
how does oxygen’s electronegativity form hydrogen bonds?
oxygen tries to steal the hydrogens of other oxygens
it really be ya own bitches
what forms water droplets?
hydrogen bonds!
what is the weakest chemical bond?
hydrogen bonds!
are the bonds between hydrogen and oxygen in H2O polar or nonpolar?
VERY polar
what kind of partial charges develop when hydrogen and oxygen join together?
oxygen is partially negative, and hydrogen is partially positive
OXYGEN IS ELECTRONEGATIVE
name three ways to illustrate H2O
bohr model, ball and stick model, space-filling (mickey mouse) model
hydrogen bonds are WEAK attractions between ______?
individual water molecules
what specifically do hydrogen bonds form between?
the HYDROGEN of one H2O molecule, and the OXYGEN of another H2O molecule because
OXYGEN IS ELECTRON GREEDY
what is cohesion?
cooperation, H2O sticks to other H2O molecules
give an example of H2O cohesion
water puddles and surface tension
what is adhesion?
H2O sticks to other polar molecules
give an example of H2O adhesion
capillary action, water sticks to polar plant stems and travels from the root to the tip, with evaporation acting as suction
list the 6 properties of water
- water has a high specific heat
- water has a high heat of vaporization
- solid water is less dense than liquid water
- water is a GREAT solvent
- water organizes nonpolar molecules
- water can form ions
what is specific heat?
the amount of energy required to raise 1 gram of water by 1 degree celcius
why is water’s high heat of vaporization important?
water can absorb a lot of heat before evaporating
think: oceans, sweat
why is solid water less dense than liquid water?
as water cools, the hydrogen bonds are stretched further apart due to air pockets in between those hydrogen bonds
why does it matter that ice is less dense than liquid water?
water is a great insulator and can float
think: lake in the winter, animals living happily under a layer of ice
what’s another name for water?
the universal solvent
why does water’s great dissolving ability matter?
it will dissolve the bonds between almost anything
ex. the ionic bonds between NaCl
what is one thing water can’t dissolve?
nonpolar molecules
why can water dissolve almost anything?
it’s SUPER polar, the oxygen tries to take everyone’s electrons
what happens when water organizes nonpolar/hydrophobic molecules?
droplets/spheres/MICELLES form
what is a micelle?
a spherical structure that forms when a nonpolar molecule contacts H2O
give a SUPER important example of micelles
the phospholipid bilayer of cell membranes!!
define hydrophobic
water fearing, nonpolar
give a real world example of a hydrophobic substance
the oil ducks secrete to help them float on water and stay warm
define hydrophilic
water loving, polar
what two ions does H2O dissociate to form?
one hydroxide ion (OH-) and one hydrogen ion (H+)
what is the basis of the pH scale?
the hydrogen ion (H+)
pH refers to the concentration of ____ in a solution
hydrogen ions (H+)
a greater pH concentration equals a ____?
lower pH number
a lower pH concentration equals a ____?
higher pH number
what is the formula for pH?
pH = -log[H+]
what kind of relationship exists between H+ concentration and pH number?
an inverse relationship
what is the range of the pH scale?
0-14
what pH does distilled water have?
7, it is neutral
what does a pH above 7 indicate?
a basic/alkaline solution
what does a pH below 7 indicate?
an acidic solution
what does a neutral pH mean?
there is an equal concentration of H+ and OH- ions
what is the average pH for human blood?
6.5
is human blood usually basic or acidic?
it is slightly acidic
what does the pH of the soil of a hydrangea effect?
the color of the hydrangea
what pH levels cause hydrangeas to be blue?
5.5 and lower
what pH levels cause hydrangeas to be pink?
6.02 and higher
pine needles ____ soil?
acidify
are acids hydrogen acceptors or hydrogen donors to a solution?
they are hydrogen donors
what does a hydrogen donor do?
releases H+ ions into a solution, which drops pH levels, ACIDS DO THIS
are bases hydrogen acceptors or hydrogen donors to a solution
hydrogen acceptors
what does a hydrogen acceptor do?
absorbs H+ ions and binds them up into OH- ions, raising pH levels
BASES DO THIS
what lowers pH levels?
an acidic solution
what do buffers do?
maintain homeostasis of blood pH
what makes up most biological buffers?
one acidic molecule and one basic molecule
give an example of a biological buffer
carbon dioxide-bicarbonate buffer
DO NOT TURN THIS OVER UNTIL YOU CAN DESCRIBE THIS WHOLE BUFFER SYSTEM
if xenon has an atomic number of 54 and a mass number of 108, how many neutrons does it have?
54
atoms that vary in the number of neutrons found in their nuclei are called ____?
isotopes
what is the weakest chemical bond?
hydrogen bonds
when acids are added to a solution, the pH should ___?
decrease
a molecule that binds up excess hydrogen ions in a solution is called a ____?
base
each carbon molecule can bond with as many as ____ other atoms or molecules?
4
why can some insects walk on water?
surface tension from hydrogen bonds
