Bio 141 SmartBook chapter 2
A hydrogen ion, formed during the dissociation of water, has a charge of which of the following?
+1
What is the charge of a hydroxide ion?
-1
Arrange the following states of water in order from most dense to least dense (start with most dense at the top).
1, liquid 2. solid 3. gas
If an atom has 6 electrons in its outermost layer, how many covalent bonds must it form in order to have a stable outer shell of electrons?
2
In a single covalent bond, ______________ total electrons are shared (please enter the number of shared electrons).
2
If an atom has 4 electrons in its outermost energy level, how many covalent bonds must it form in order to have a stable outer shell of electrons?
4
In a double covalent bond, __________ total electrons are shared (please only enter the number of shared electrons).
4
An electrically neutral atom has an atomic number of 6 and an atomic mass of 14. This atom has_____ protons, ______ neutrons, and _______ electrons.
6,8,6
An atom has 8 protons, 9 neutrons, and 8 electrons. This atom has an atomic number of ______, an atomic mass of _____, and an overall charge of ______.
8, 17, 0
Molecules that are more polar tend to have which of the following characteristics?
A higher heat of vaporization A higher specific heat
Atomic mass is measured in which of the following units?
Daltons (Da)
Which of the following are molecular formulas?
H2 O2
What is the temperature of a substance a measure of?
How fast its molecules are moving
Where are the valence electrons of an atom found?
In the outermost energy level only
How are ions formed?
Ions are formed when atoms lose or gain one or more electrons.
What is true of a molecule of gaseous hydrogen (H2)?
It has no net charge.
Select the reasons that the molecule formed by two hydrogen atoms (H2) is stable.
It has no net charge. It has no unpaired electrons. It is held together by a covalent bond.
Which subatomic particles are located in the nucleus of an atom?
Neutrons Protons
Which of the following are structural formulas?
O=O H—H
Which two particles are the primary determinants of an element's atomic mass?
Protons Neutrons
Which of the following is the definition of the heat of vaporization of water?
The amount of energy needed to change 1 g of water from a liquid to a gas
Water has several properties important to life: high specific heat, high heat of vaporization, lower density in solid form (ice), ability to act as a solvent and to organize nonpolar molecules. What explains these properties of water?
The polar nature of water molecules
A neutral atom has no net electrical charge. Why?
There are equal numbers of protons and electrons in the atom.
If two atoms belong to the same element, which of the following must be true?
They must have the same number of protons.
When NaCl is formed, ______.
a sodium atom loses an electron, while a chlorine atom gains an electron
When NaCl is formed, __________.
a sodium atom loses an electron, while a chlorine atom gains an electron
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 a(n)
anion
Atoms with a net negative charge are known as _____________, whereas atoms with a net positive charge are known as ______________.
anion, cation
A sodium atom that has lost an electron and has an overall positive charge is an example of which of the following?
cation
The number and configuration of electrons determines an element's ______.
chemical properties
Because polar water molecules attract each other, water is said to be ___________.
cohesive
A(n) _________________ bond is formed when 2 atoms share one or more pairs of valence electrons.
covalent
In structural formulas, each solid line between atomic symbols represents a single ___________ bond
covalent
Water consists of one oxygen atom joined to two hydrogen atoms by two single, polar _________ bonds
covalent
Water consists of one oxygen atom joined to two hydrogen atoms by what type of bonds?
covalent
What type of bond is formed when 2 atoms share one or more pairs of valence electrons?
covalent
True, discrete molecules form when atoms are connected by
covalent bonds
If an atom gains or loses a(n) ____________ , it acquires a net electrical charge and becomes an ion.
electron
The affinity of an atom for an electron is also known as which of the following?
electronegativity
An atom is composed of a central nucleus which is surrounded by which orbiting particles?
electrons
Atoms differ in their affinity for __________, a property called electronegativity.
electrons
Atoms differ in their affinity for ____________ , a property called electronegativity.
electrons
Redox reactions involve a transfer of ____________ from one atom to another.
electrons
Subatomic particles called __________ can be found at various distances from the nucleus (please only write the name of the particle without specifying its charge or other properties).
electrons
The chemical behavior of an atom is determined by the number and configuration of its
electrons
The green spheres (indicated by arrows) in the simple "Bohr model" of atoms shown here represent
electrons
A substance that cannot be broken down into simpler substances by ordinary chemical means is called a(n)
element
What do we call a substance that cannot be broken down into simpler substances by ordinary chemical means?
element
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
The amount of energy required to change 1 g of a substance from a liquid to a gas is called which of the following?
heat of vaporization
If two atoms are joined by a polar covalent bond, the shared electrons will tend to stay closer to the atom with
higher electronegativity
__________ atoms usually have no neutrons.
hydrogen
____________ atoms always have one proton.
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
Which property of water strongly affects the overall shape of many biological molecules, such as protein, and DNA?
hydrophobic exclusion
Within an atom, where are electrons found?
in the orbitals that surround the nucleus
The atoms in NaCl are held together by what type of bond?
ionic
Unlike ____________ bonds, which produce a crystal lattice, ______________ 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
What does it mean when we say water is adhesive?
it is attracted to other polar molecules and ions
Solid water is __________ dense than liquid water.
less
When writing out structural formulas, covalent bonds are represented by solid _______________ between atomic symbols.
lines
A dalton is a unit of which of the following?
mass
Anything that has mass and occupies space is defined as
matter
can be defined as any substance that has mass and occupies space.
matter
A group of atoms held together by chemical bonds in a stable association is called which of the following?
molecule
A(n) _____________ is made of two or more atoms held together by chemical bonds in a stable association. The atoms may or may not belong to the same element.
molecule
Isotopes are atoms of the same element that differ in the number of which of the following?
neutron's
Isotopes differ in the number of _________ they contain
neutrons
Which of the following are subatomic particles?
neutrons protons electrons
Almost all the mass of an atom is located in the
nucleus
Where is most (almost all) of the mass of an atom located?
nucleus
Generally speaking, an atom is made of a central__________ which is surrounded by orbiting ____________.
nucleus, electrons
An atom's electrons are typically found in regions called _________________ ; those regions can be found at varying distances from the nucleus.
orbitals
An atom's electrons are typically found in regions called __________________; those regions can be found at varying distances from the nucleus.
orbitals
Chemical reactions that involve a transfer of electrons from one atom to another are called ___________________ reactions.
oxidation reduction
If two atoms are joined by a polar covalent bond, the atom with the lower electronegativity will have a partial ___________ charge.
positive
Among subatomic particles, a(n) ___________ has a charge of +1, a(n) )_____________ has a charge of -1, and a(n) ____________ has no charge.
proton, electron, neutron
Atoms of the same element always have the same number of _____________ in the nucleus, and this number is unique for that element.
protons
Atoms of the same element always have the same number of___________ in the nucleus, and this number is unique for that element.
protons
In the simple "Bohr model" of atoms shown here, the tan spheres (identified by arrows) represent which of the following?
protons
The atomic number of an element refers to the number of ________ in the atoms of that element
protons
atomic number refers to the number of __________ in an atom
protons
The atomic mass of an atom is equal to the sum of the masses of its ___________ and ____________
protons and neutrons
Which subatomic particles determine the atomic mass of an atom?
protons and neutrons
Atoms of different chemical elements can be differentiated based on the number of
protons in the nucleus
The three main types of subatomic particles are ____________, ______________, and _____________
protons, neutrons, electron
Within an atom, _____ and ______ have nearly equal masses, while ______ have a much smaller mass.
protons; neutrons; 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 __________ of a substance is a measure of how rapidly its individual molecules are moving.
temperature
In a neutral atom, the number of electrons is equal to which of the following?
the atomic number
The pH of a solution is defined as
the negative logarithm of the hydrogen ion concentration
In a single covalent bond, _______________ total electrons are shared (please enter the number of shared electrons).
two
Electrons in outer, unfilled energy levels are known as ______________ electrons
valence
When 1 g of fructose is dissolved in 500 mL of water, _____________ is the solvent and __________ is the solute.
water fructose
If two atoms have the same number of protons in their nucleus, you can conclude for sure that they
are atoms of the same element
Water is cohesive because water molecules are
attracted to each other
A(n) ___________ is a substance or a mixture of substances that act to resist changes in pH.
buffer
