chpt 2 questions
Ionic bonds involve which of the following?
-An attraction between atoms with opposite electrical charges -A transfer of electrons from one atom to another
Which of the following statements about orbitals is true?
-Each orbital contains a maximum of 2 electrons. -Several different orbitals may occupy the same energy level. -Orbitals are three dimensional shapes which indicate areas where electrons are most likely to be found.
Select the reasons that the molecule formed by two hydrogen atoms (H2) is stable.
-It is held together by a covalent bond. -It has no net charge. -It has no unpaired electrons.
How does water's high heat of vaporization affect living organisms?
-Many organisms sweat or pant in order to cool themselves. -When your body is wet, you feel cooler than when your body is dry.
Which of the following statements about orbitals is true?
-Orbitals are three dimensional shapes which indicate areas where electrons are most likely to be found. -Each orbital contains a maximum of 2 electrons. -Several different orbitals may occupy the same energy level.
Which of the following do not occur during a chemical reaction?
-The number of atoms present may increase or decrease. -
Which of the following do not occur during a chemical reaction?
-The number of atoms present may increase or decrease. -Atoms may be created or destroyed.
Choose the true statements about hydrogen bonds.
-They can occur between two parts of a large molecule. -They can occur in any case when hydrogen is bound to a more electronegative atom.
Which of the following are descriptive of energy levels?
-They indicate an electron's relative distance from the nucleus. -They indicate the amount of potential energy an electron contains. -They are often drawn as circles around the nucleus. -They consist of one or more orbitals.
Identify the characteristics of Van der Waals forces.
-They occur only when two atoms are very close together. -They are weak.
Elements possessing all eight electrons (two for helium) in their outer energy level are said to be
-noble gases -inert
If you dissolve 0.05 mol of sugar into 100 ml of water, the result is which of the following?
0.5 M solution of sugar
Rank the following bonds and interactions in order from strongest to weakest starting with the strongest at the top. (assume that these bonds/interactions are occurring in a living cell) Position 1 of 5 Ionic bond incorrect toggle button unavailable Ionic bond
1 covalent bond 2 ionic bond 3 hydrogen bond 4 hydrophobic interaction 5 van der waals attraction
the molecule formed by the 2 hydrogen atoms is stable for 3 reasons
1 the has no net charge 2 the octet rule is satisfied 3 it has no unpaired electrons
If a solution has a pH of 3, then its hydrogen ion concentration is which of the following?
1 x 10-3 M
According to the pH scale shown, seawater is _______ acidic than household ammonia.
1,000 times more
According to the pH scale shown, tomatoes are _______ acidic than urine.
100 times less
In a single covalent bond, ___ total electrons are shared (please enter the number of shared electrons).
2
In a single covalent bond,____ total electrons are shared
2
According to the octet rule, the first energy level is stable with _______ electrons and the outermost energy level is stable with ______ electrons
2 8
A molar concentration of 2 M is equal to which of the following?
2 mol/L
An element has five electrons in its outer shell. As such, it needs how many electrons to fill its outer energy level?
3
In a double covalent bond, how many total electrons are shared (please only enter the number of shared electrons)?
4
The neutral point of the pH scale is
7
If a solution has a [H+] of 10-9 M, then its pH is ______
9
Which of the following describes a covalent bond between two atoms in which electrons are NOT equally shared?
A covalent bond between two atoms which differ greatly in their electronegativity
What happens when water dissociates?
An equal amount of H+ and OH- ions are produced.
Which of the following best describes the entire basic (alkaline) range of the pH scale?
Any pH value above 7
Which of the following best describes the entire acidic range of the pH scale?
Any pH value below 7
Why is solid water less dense than liquid water?
As the movement of water molecules slows down when liquid water changes to ice, hydrogen bonds form that space the molecules relatively far apart.
Why does water have very high specific heat?
Because a large input of thermal energy is required to break the many hydrogen bonds between individual water molecules
When an acid is added to the blood, how does the carbonic acid/bicarbonate buffer work to stabilize pH?
Bicarbonate removes H+ from the blood.
Which of the following bonds are nonpolar?
C--C O=O C--H H--H
If a substance removes H+ from the blood, causing the pH of the blood to rise, how does the carbonic acid/bicarbonate buffer work to stabilize pH?
Carbonic acid releases H+ into the blood.
Water consists of one oxygen atom joined to two hydrogen atoms by what type of bonds?
Covalent
The different energy levels of electrons within atoms can be described as which of the following?
Each energy level corresponds to a specific quantum of energy.
Select the polar molecule.
H2O
The attraction between the partially negative oxygen atom of one water molecule and the partially positive hydrogen atom of another water molecule is called a(n) _________
HYDROGEN
Consider a large protein molecule that has some parts that are highly hydrophobic. When placed in a water solution, the protein folds in a globular shape, such that all the hydrophobic portions are inside the molecules, away from water. This is an example of which of the following?
Hydrophobic exclusion
Where are valence electrons found?
In the outermost energy level only
Typically, as the temperature increases, what happens to the rate of a chemical reaction?
It also increases.
How does water's high specific heat affect living organisms?
It helps prevent organisms from overheating due to the thermal energy released by chemical reactions inside cells. It helps organisms maintain a relatively stable internal temperature when the external temperature rises or falls.
Which of the following statements about the pH of cells are true?
Most enzymes in living systems are extremely sensitive to pH. It is important for cells to maintain a fairly constant pH. Even small changes in pH can alter the shape of enzymes and other proteins.
Which of the following molecules are nonpolar?
N2 CH4 O2
Which of the following may occur during a chemical reaction?
New types of molecules are formed. Atoms are transferred from one molecule to another. New chemical bonds are formed. Existing chemical bonds are broken.
Why does water tends to exclude nonpolar molecules?
Nonpolar molecules disrupt the hydrogen bonds between water molecules.
Choose all of the following bonds that are polar?
O--H C--N C--O
A single water molecule can spontaneously break apart (ionize) to form which of the following?
One positive hydrogen ion and one negative hydroxide ion
Water molecules are attracted to which of the following (choose all that are correct)?
Polar molecules Ions Other water molecules Substances that bear an electrical charge
The symbol [H+] means which of the following?
The molar concentration of hydrogen ions
Atoms are chemically the most stable when which of the following occurs?
Their outer electron shell is full.
Water is cohesive. Which describes this feature of water molecules?
They are attracted to each other.
Identify the two key properties of hydrogen bonds.
They are highly directional. They are weaker than covalent bonds.
How can scientists use radioactive isotopes to accurately determine the age of a biological sample?
They measure the ratio of different carbon isotopes in the sample.
Which of the following correctly describes electrons within atoms?
They occupy discrete energy levels.
When non-polar molecules are placed in water, they tend to clump, thus minimizing the disruption of hydrogen bonds between water molecules. Which of the following does that explain?
Water excludes non-polar molecules.
How is the arrangement of water molecules related to its density?
Water molecules in ice are locked into a crystal-like lattice due to hydrogen bonds, making ice less dense than liquid.
Choose the two "partners" in a hydrogen bond between water molecules.
a hydrogen atom with a partially positive charge an oxygen atom with a partially negative charge
A substance that increases [H+] and decreases pH when it dissociates in water is called a(n)
acid
The attraction of water to other polar substances is called
adhesion
A chlorine atom that has gained an electron and has an overall negative charge is an example of
anion
water is less dense as a solid than as a liquid
aquatic organisms can survive below the frozen surface of ponds and lakes
A substance that decreases [H+] and increases pH when it dissociates in water is called a(n)
base
Buffers stabilize pH by releasing hydrogen ions when a(n) ______ is added and absorbing hydrogen ions when a(n) _________ is added
base acid
Water has a high heat of vaporization because it takes a large amount of energy to
break the hydrogen bonds between different water molecules.
_______ is a substance or a mixture of substances that act to resist changes in pH.
buffer
_________is a substance or a mixture of substances that act to resist changes in pH.
buffer
How would a buffer prevent the acidification of a solution when an acid is added to it?
by absorbing hydrogen ions
A sodium atom that has lost an electron and has an overall positive charge is an example of
cation
A chemical reaction involves the breaking and formation of _______ ________
chemical bonds
A chemical reaction involves the breaking and formation of ________ _________
chemical bonds
Chemical bonds are broken and new bonds are formed during a(n) _____ ________
chemical, reaction
Because the polar water molecules attract each other, water is said to be _______
cohesive
A substance whose molecules are made of atoms of more than one element held together by chemical bonds is called a(n)
compound
What do we call a substance composed of atoms of more than one element that are held together by chemical bonds?
compound
The symbol [H+] represents the molar ______ of hydrogen ions
concentration
Each water molecule consists of one oxygen atom joined to two hydrogen atoms by two single _______ BONDS
covalent
What type of bond is formed when two atoms share one or more pairs of valence electrons?
covalent
____ bond is formed when two atoms share one or more pairs of valence electrons.
covalent
_______ bond is formed when two atoms share one or more pairs of valence electrons.
covalent
Which of the following bonds involves the sharing of one or more pairs of electrons?
covalent bond
When an acid is dissolved in water, it _____ the solution's pH by _ the amount of protons )H+) in the solution
decreases increasing
Hydrogen bonds can help to maintain the structures of large biological molecules because they are highly
directional
Water molecules are attracted to any substance that has a(n) ________ charge, whether it be full (such as an ion), or partial (such as a polar molecule).
electric
The affinity of an atom for an electron is also known as
electronegativity.
Atoms differ in their affinity for ________ , a property called electronegativity.
electrons
The number and configuration of ______ determines the chemical behavior of an atom.
electrons
When a bond forms between two atoms, such that one or more pairs of ____ are equally shared, the bond is termed nonpolar.
electrons
In living organisms, almost all chemical reactions are catalyzed by protein catalysts called
enzymes
In living systems, which of the following catalyze almost every chemical reaction necessary for life?
enzymes
True or false: Unlike covalent bonds, which produce a crystal lattice, ionic bonds are formed between 2 individual atoms, giving rise to true, discrete molecules.
false
The element Chlorine (Cl) has 7 electrons in its outermost shell. Therefore, chlorine is
highly reactive and tends to gain an extra electron.
The attraction between the partially negative oxygen atom of one water molecule and the partially positive hydrogen atom of another water molecule is called a(n) _______
hydrogen
It takes a large amount of heat energy to break ______ bonds between water molecules; this explains why water has a very ________ heat of vaporization.
hydrogen high
attraction between a covalently bound H atom with a slight positive charge and another covalently bound atom with a slight negative charge
hydrogen bond
Water has a high specific heat because a large input of thermal energy is needed to break the many ________ ________ that restrict the movement of individual water molecules
hydrogen bonds
Of the following list of bonds and interactions, which one is the weakest?
hydrophobic interaction
nonpolar regions of a molecule are forced together in order to minimize contact with water molecules
hydrophobic interaction
Which trace element is found in thyroid hormones?
iodine
Bonds that form due to the attraction between oppositely charged atoms that have gained or lost electrons are called
ionic
attraction between oppositely charged atoms
ionic
_____ bonds typically produce a crystal matrix. In contrast, ______ bonds are formed between 2 individual atoms, giving rise to true, discrete molecules.
ionic, covalent
Atoms in which the number of electrons does not equal the number of protons are called
ions
Atoms that have gained or lost electrons, and are therefore no longer electrically neutral, are called
ions
The chemical behavior of an atom depends on the number and configuration of its
ions
What is true of a molecule of gaseous hydrogen (H2)?
it has no net charge
What does it mean when we say water is adhesive?
it is attracted to other polar molecules and ions
Fish and other animals can survive at the bottom of a lake during winter because ice is ____ dense than liquid water
less
During radioactive decay, an atom typically breaks up into elements with which of the following?
lower atomic numbers
A base is a substance that
lowers [H+] and increases the pH when it dissociates in water
solubility
many types of ions and molecules move freely in cells, permitting a diverse array of chemical reactions
A group of atoms held together by one or more covalent bonds in a stable association is called which of the following?
molecule
Isomers differ in the number of ____ they contain
neutrons
Isotopes are atoms of the same element that differ in the number of
neutrons
Isotopes differ in the number of ____ they contain
neutrons
electron __________ represent probability distributions for electrons, that is, regions surrounding the nucleus where there is the highest probability of finding electrons.
orbitals
high heat of vaporization
organisms sweat or pant to cool themselves
An atom participating in a chemical reaction loses one or more electrons. The process of losing an electron in a reaction is called
oxidation
A water molecule is shaped similar to a tetrahedron, with the _______ atom at its center, ________ atoms at two of the apexes and partial ______ charges at the remaining two apexes.
oxygen , hydrogen, negative
A hydrogen bond can form between the partially negative _______ atom of one water molecule and the partially positive _____ atom of another water molecule
oxygen, hydrogen
Substances or a mixture of substances known as buffers, act in living things to resist changes in
pH
_____ of a solution is defined as the negative logarithm of the hydrogen ion concentration.
pH
cohesion
plant leaves pull water up from the roots
_____ covalent bond is formed by an unequal sharing of one or more electron pairs.
polar
Which bond is formed by an unequal sharing of one or more electron pairs?
polar covalent
Atomic number refers to the number of
protons
the number of ____ in an atom determines the atom's atomic number.
protons
An ion with an overall charge of +1 has an atomic number of 11 and an atomic mass of 23. This atom has
protons-11 neutrons- 12 electrons- 10
by determining the _____ of the different isotopes of carbon in a sample, scientists are able to accurately determine the age of the sample.
ratio
Covalnet bond
sharing of electrons
When 1 g of sugar is dissolved in 500 mL of water, the sugar is called the ______ and water is called the______
solute solvent
the property of _____________ heat measures the extent to which a substance resists changing its ______________ when it absorbs or loses heat
specific temperature
The amount of heat 1 g of a substance must absorb or lose to change its temperature by 1°C is called
specific heat
When the pH of a solution rises by 1 which of the following happens?
the [H+] decreases 10-fold
When the pH of a solution falls by 2
the [H+] increases 100-fold
Elements, such as zinc and iodine, which are found in very small amounts in living things, but play crucial roles in biological processes, are known as which of the following?
trace elements
Which of the following is the strongest bond?
triple covalent bond
True or false: Hydrophobic exclusion affects the overall shape of many biological molecules as well as how they interact and fit together.
true
True or false: When water dissociates, hydrogen ions and hydroxide ions are produced in equal amounts.
true
Electrons in outer, unfilled energy levels are known as ______ electrons
valence
weak attraction between atoms due to oppositely polarized electron clouds
van der Waals attraction
a _____ molecule can break apart to form a positive hydrogen ion and a negative hydroxide ion.
water
When 1 g of sugar (sucrose) is dissolved in 500 mL of water, _____ is the solvent, _____ is the solute and sucrose is said to be _______ in water
water sugar soluble
high specific heat
water stabilizes the temperature of organisms and the environment
Water helps living things maintain a relatively constant internal temperature and protects cells from overheating due to the heat released by chemical reactions. What property of water is responsible for that?
waters high specific heat
