Name the essential elements in living organisms correct answers C, N, H, O (S+P)
What is the smallest living unit and smallest non living unit correct answers cell, atom
Given an atom's protons, neutrons, and electrons, state an atom's mass number & atomic number and vice versa correct answer...
Bio 240 exam 1 || 100% CORRECT SOLUTIONS.
Name the essential elements in living organisms correct answers C, N, H, O (S+P)
What is the smallest living unit and smallest non living unit correct answers cell, atom
Given an atom's protons, neutrons, and electrons, state an atom's mass number & atomic
number and vice versa correct answers protons=atomic number
neutrons+protons= mass number
Determine valence electrons if given total number of electrons for an atom and/or its electron
diagram (includes determining how many electrons occupy the first 3 shells) correct answers
1st shell has 2
2nd shell has 8
Third has 8
Explain what the numbers around an element's symbol mean correct answers on top means
mass number on bottom means atomic number
Define isotope and what is different between different isotopes of the same element correct
answers isotope- an atom with a given number of neutrons
Different isotopes have different numbers of neutrons. The number given is mass number (c-
12 has 6 neutrons)
Provide examples of how isotopes can be used in real-life correct answers C-14 is used for
dating how long ago an organism has died
Some uranium isotopes are used in nuclear reactors/bombs while others cannot be used for
this purpose
Determine the number of atomic bonds an atom can form based on its valence electrons
correct answers typically an atom will fill to have 8 electrons by gaining or losing electrons
through ionic or covalent bonds
Describe the different types of atomic bonds (polar covalent, nonpolar covalent, and ionic)
and how each form in terms of unequal/equal sharing of electrons or stealing electrons correct
answers Polar covalent- One atom stronger pull on electrons than other making a polar
covalent bond.
Nonpolar covalent- only occurs btwn atoms of same element and electron sharing is truly
equal.
ionic- One atom nearly totally takes the electron from the other (Na totally loses electron to
Cl and they are held together bc of charges)
Identify the type of atomic bond that will form between C, H, N, O, F based on their valences
and relative electronegativities correct answers more electronegative elements are to the top
right, Flourine will always be most electronegative element. Hydrogen does not form ionic
bonds
Predict the properties of molecules (no charge, partial charges, or full charges) based on the
chemical bonds within them correct answers Look at electroneg. of which elements are
, connected to which elements. also look at shape of molecule because symmetrical molecules
are nonpolar
Define hydrogen bonding and how/why it forms through partial charges correct answers
Hydrogen bonding occurs between the polar parts of molecules that have F, O, N. The + and -
partial charged parts of the molecules stick together.
Identify properties that would make a molecule hydrophilic/hydrophobic. correct answers
Polar- hydrophilic
Nonpolar- Hydrophobic
Describe each of water's unique properties below and how they impact life (1) as a solvent
(2) adhesion and cohesion (3) moderation of temperature (4) expansion upon freezing correct
answers 1) Water's small structure and hydrogen bonding allows it to dissolve many
substances
2) If one goes, others want to come so water stays together. surface tension is due to
cohesion.
3)Water is harder to separate due to its hydrogen bonding so it helps control temperatures as
it is hard to evaporate but when it does it takes energy out of the atmosphere.
4) Water forms a crystalline lattice structure so when it freezes it expands because the
structure creates a distance between the molecules.
Describe how hydrogen bonding allows for water's unique properties correct answers
Hydrogen bonding allows water to stick together very well as well as dissolve many
substances and have great surface tension.
Describe how acids and bases affect the pH of an aqueous solution (the change they make to
pH and what they do to change the pH) correct answers acids- low pH
bases- high pH
Define buffer and its application for pH in biological systems correct answers The buffer in
blood keeps the pH of our blood relatively the same by an equilibrium reaction that pulls out
or puts in H+ ions
Calculate pH and pOH given hydrogen or hydroxide ion concentration and calculate
hydrogen or hydroxide ion concentration given pH or pOH correct answers pH= -log(H+)
pOH= -log(OH-)
pH= 14-pOH
10^pH= [H+]
10^pOH= [OH-]
Explain why carbon's number of bonds allows for such variety of structure and partners
correct answers Since Carbon will form 4 bonds, it will be able to create shapes that branch
off more than if it were able to form less bonds.
List the variations of structure that hydrocarbons can have correct answers Hydrocarbons can
form different length chains, branch off in different ways, form rings. Carbon skeletons vary
in length. Skeletons may be branched or unbranched. The skeleton may have double bonds
which can vary in location. Some skeletons are arranged in rings.
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