Unit 1 (Chapter 2, Test Yourself Questions) Flashcards
_______________ makes up the nucleus of an atom.
Protons and neutrons
Living organisms are composed of mainly of which atoms?
Carbon, hydrogen, oxygen, and nitrogen.
The ability of an atom to attract electrons in a bond with another atom is termed its?
Electronegativity
Hydrogen bonds differ from covalent bonds in that?
Covalent bonds involve sharing of electrons between atoms, but hydrogen bonds are the result of week attractions between a hydrogen atom of a polar molecule and an electronegative atom of another polar molecule.
A free radical (2)…
can cause considerable damage and is an atom with one unpaired electron in its outer shell.
Chemical reactions in living organisms (4)….
1 - Require energy to begin
2 - usually require a catalyst to speed them up
3 - are usually reversible
4 - occur in liquid environments, such as water
Solutes that easily dissolve in water are said to be (2)….
1 - hydrophilic
2 - polar molecules
The molecular mass of glucose is about 180 g/mole. If 45 g of glucose is dissolved in water to make a final volume of 0.5 L, what is the molarity of the solution?
Remember: Divide the moles of the solute by the volume of the solution expressed in liters.
.5 M
The sum of the atomic masses of all atoms of a molecule is its?
Molecular weight
Reactions in which water is used to break apart other molecules are known as ____________ reactions.
hydrolysis
Compare and contrast the different types of bonds commonly found in biological molecules.
Covalent bonds are bonds in which atoms share electrons.
A nonpolar covalent bond is one between two atoms of similar electronegativities, such as two carbon atoms.
A polar covalent bond is one between two atoms of dissimilar electronegativities.
A hydrogen bond is a weak interaction that forms when a hydrogen atom in a polar molecule becomes electrically attracted to an electronegative atom.
Van der Waal dispersion forces are temporary, weak interactions, resulting from random electrical forces generated by the changing distributions of electrons in the outer shells of nearby atoms.
A strong attraction between two oppositely charged atoms forms an ionic bond.
What is the significance of molecular shape, and what may change the shapes of molecules?
Within limits, bonds within molecules can rotate and thereby change the molecule’s shape.
This is important because it is the shape of a molecule that determines, in part, the ability of that molecule to interact with other molecules.
Also, when two molecules do interact through such forces as hydrogen bonds, the shape of one or both molecules may change as a consequence.
The change in shape is often part of the mechanism by which signals are sent within and between cells.
Compared with liquid water, ice has ______.
Multiple select question.
fewer hydrogen bonds between individual water molecules
more hydrogen bonds between individual water molecules
a more orderly arrangement of water molecules
a less orderly arrangement of water molecules
more hydrogen bonds between individual water molecules
a more orderly arrangement of water molecules
Hydrolysis reactions ______.
Multiple choice question.
break apart molecules via water
create molecules via the loss of a smaller molecule
create molecules via the loss of water
break apart molecules via water
Which ions are produced when water ionizes?
Multiple select question.
H–
H+
OH+
OH–
O2
H+
OH–
What are the concentrations of H+ and OH- ions in pure water?
Multiple select question.
[OH-] = 10-7 M
[OH-] = 10-2 M
[H+] = 1.0 M
[H+] = 102 M
[H+] = 10-7 M
[OH-] = 1.0 M
[OH-] = 10-7 M
[H+] = 10-7 M
A base will release __________
ions when dissolved in water.
OH, hydroxyl, OH-, hydroxide, or negative
Hydrochloric acid is considered an acid because it releases _________ ions into solution.
hydrogen, H+, protons, H+ ions, H, or hydronium
Water is used to break apart another molecule in a(n) __________ reaction.
Hydrolysis
The ______ of a solution is the negative base 10 logarithm of the H+ concentration of the solution.
Multiple choice question.
equilibrium constant
heat of vaporization
heat capacity
pH
pH
Pure water can ionize into which of the following?
Multiple choice question.
Positively charged protons (H+) and negatively charged hydroxide (OH-) ions
Negatively charged dihydroxide (H2-) ions and positively charged oxygen ions (O+)
Positively charged dihydroxide (H2+) ions and negatively charged oxygen ions (O-)
Positively charged hydroxide (OH+) ions and negatively charged protons (H-)
Positively charged protons (H+) and negatively charged hydroxide (OH-) ions
What type of compound minimizes pH fluctuations in the fluids of living organisms?
Multiple choice question.
buffer
base
acid
water
Buffer
A substance that absorbs hydrogen ions in solution is called a(n) ______.
Multiple choice question.
salt
base
isotope
buffer
acid
Base
A substance that releases hydrogen ions into solution is called a(n) ___
acid
pH is defined as the _______ ___________ to the base 10 of the ________ ion concentration.
Negative logarithm; H+
