ch 2 chemical foundations of life Flashcards
what is the simplest, most common element?
hydrogen
how many protons, neutrons, and electrons does oxygen have?
8
how many protons, neutrons, and electrons does carbon have?
6
what is the approximate mass of a single proton or neutron?
1 dalton
what are isotopes?
atoms of the same element that have different atomic mass numbers due to different numbers of neutrons
What are ions?
charged atoms
Is hydrogen flammable?
yes
Why is iron very useful?
it can exist in multiple charged states
how many naturally occurring elements are there?
90
What elements make up 96.3% of humans?
C, H, O, N
What are characteristics of cations?
they have fewer electrons than protons and are positively charged
what are the characteristics of anions?
they have more electrons than protons and are negatively charged
What determines an element’s chemical properties?
its interactions between valence electrons of other atoms
what are redox reactions?
electrons are transferred from one atom to another
what is oxidation?
the loss of an electron
what is reduction?
the gaining of an electron
what are molecules?
atoms held together in a stable association
when do covalent bonds form?
when atoms share two or more valence electrons
when are covalent bonds stronger than others?
single bond < double bond < triple bond < etc.
what compound is the cell membrane made of?
hydrocarbons
is the cell membrane polar or non-polar?
non-polar
what conducts electricity better? sea water or tap water
sea water
why is water often thought to conduct electricity?
it is not the water itself but the dissolved solutes in the water that conduct
What are non-polar covalent bonds?
bonds where there is an equal sharing of electrons
What are polar covalent bonds?
bonds where there is an unequal sharing of electrons
how are ionic bonds formed?
they are formed by the attraction of oppositely charged ion
what are chemical reactions?
the formation of or breaking of chemical bonds
why do cold-blooded animals eat so much less than warm blooded animals?
because to maintain a constant body temperature takes a large amount of energy
What is this chemical reaction?
6H2O + 6CO2 —> C6H12O6 + 6O2
photosynthesis
What is this chemical reaction?
C6H12O6 + 6O2 —> 6H2O + 6CO2
cellular respiration
what are hydrogen bonds?
weak attractions between the partially negative oxygen of one water molecule and the positive hydrogen of a different water molecule
What holds an H2O molecule together?
polar covalent bonds
What bond connects H2O molecules to each other?
hydrogen bonds
What is the universal solvent?
water
what is cohesion?
when water molecules stick to other water molecules by hydrogen bonding
what is adhesion?
when water molecules stick to other polar molecules by hydrogen bonding
What causes capillary action?
adhesive forces exceeding cohesive forces between water molecules
What is the calorie of heat?
the amount of energy needed to get 1g of H2O to rise 1 degree celsius
How much less dense is water in its solid state than in its liquid state?
9%
What can dissolve polar molecules and ions by forming neutral barriers around them?
water
are hydrophilic molecules charged or not charged?
charged
Are hydrophobic molecules charged or not charged?
not charged
what causes hydrophobic molecules to aggregate or assume certain shapes?
water
what is the basis of the pH scale?
Hydrogen ions
if something has a greater hydrogen ion (H^+1) concentration, does it have a lower or higher pH?
lower pH (acidic)
if something has a lesser hydrogen ion (H^+1) concentration, does it have a lower or higher pH?
higher pH (basic)
what does it mean that water has a high specific heat?
a large amount of energy is needed to change the temperature
What does it mean that water has a high heat of vaporization?
evaporation of water from a surface requires a large amount of energy
water can interact with something as long as it has a ______.
charge
what is the pH of pure water?
7
what is the pH of blood?
slightly higher than 7
what is an acid?
a chemical that releases protons/ H^+1 ions
what is a base?
a chemical that accepts protons/ H^+1 ions
What accepts and releases H^+1 ions as necessary to keep a constant pH?
buffer
what do most biological buffers normally consist of?
a pair of molecules, one acid and one base
what are neutral atoms?
atoms that have the same number of protons and electrons (inert elements/noble gasses)
how many of the naturally occurring elements are found in living organisms in substantial amounts?
12
what is the octet rule?
atoms want a full outer orbital; they must either lose or gain electrons to do so
what is electronegativity?
an atom’s affinity for electrons
within a water molecule, the bonds between oxygen and hydrogen are highly polar because…
oxygen is partially negative and hydrogen is partially positive
what do differences in electronegativity dictate in covalent bonds?
how electrons are distributed
nonpolar covalent bonds = ________ sharing of electrons
equal
polar covalent bonds = ________ sharing of electrons
unequal
How are ionic bonds formed?
They are formed by the attraction of oppositely charged ions; the electron is taken not shared
What happens during chemical reactions?
The breaking or formation of chemical bonds
What can influence wether or not a chemical reaction happens?
Temperature, concentration of reactants and products, and the availability of a catalyst
