Learn Smart PKA- Chapter Two: The Chemical Basis of Life I: Atoms, Molecules, and Water

An atom's atomic number represents: the number of electrons plus the number of neutrons the number of protons plus the number of neutrons the number of protons the number of protons plus the number of electrons

the number of protons

When water freezes: water molecules are packed into a less dense formation water loses its hydrophilic status and becomes more hydrophobic the H2O molecules in ice are in a much more orderly arrangement than in the liquid state the rate of hydrogen bond breakage slows

water molecules are packed into a less dense formation. the H2O molecules in ice are in a much more orderly arrangement than in the liquid state. the rate of hydrogen bond breakage slows.

What four elements are the most common in living organisms? Calcium Carbon Oxygen Nitrogen Hydrogen Iron Sodium

1. carbon 2. oxygen 3. nitrogen 4. hydrogen

In humans, water comprises approximately ______ of body weight. 20-30% 40-50% 80-90% 60-70%

60-70%

In animals, what buffer is primarily responsible for maintaining the pH of body fluids? Ammonia Bicarbonate Hydrochloric acid Citric acid

Bicarbonate

A substance that releases hydrogen ions into solution is called a(n) .

acid

An ionic bond forms when a positively charged ion, called a(n) ________ , interacts with a negatively charged ion, called a(n) ________.

cations anions

Hydrochloric acid is considered an acid because it releases _____ ions into solution.

hydrogen

What type of bond forms when a cation with a positive charge interacts with an anion carrying a negative charge? Ionic van der Waals Polar covalent Non-polar covalent

ionic

Amphipathic molecules have both _______ regions and regions _________.

polar nonpolar

Which of the following is the best description of the modern model of atomic structure? A central nucleus surrounded by cloudlike orbitals containing electrons A collection of positive and negative charges uniformly distributed throughout the atom A central nucleus surrounded by electrons traveling in clearly defined orbits

A central nucleus surrounded by cloudlike orbitals containing electrons

polar covalent bond

Bond in which two atoms share electrons unequally

What occurs during all chemical reactions? Products are converted to reactants. Energy is converted to chemicals. Chemical bonds are broken or formed.

Chemical bonds are broken or formed.

In the bicarbonate pathway, the combining of carbon dioxide and water that produces carbonic acid can lower the pH because: O2 can be released OH- can be released CO2 can be released H+ can be released

H+ can be released Rationale: Carbonic acid dissociates into H+ atoms, thereby lowering the pH.

A substance that absorbs hydrogen ions in solution is called a(n) base. acid. isotope. salt.

base

Ionic bond

bond between a cation and an anion

hydrogen bond

bond between atoms with partial positives and partial negative charges

nonpolar covalent bond

bond in which two atoms share electrons equally

Atoms share a pair of electrons when they form a(n) ______ bond.

covalent

What determines whether a covalent bond is polar or nonpolar? ratio of neutrons to protons in each atom electronegativity of the atoms involved in the bond time since the bond has formed temperature of the solution

electronegativity of the atoms involved in the bond

True or false: An element is made up of two or more types of atoms.

false

Atoms tend to be most stable when their outer shells are _______ ; this can be accomplished by gaining, losing, or sharing _________

full electrons

An amphipathic molecule: has polar regions dissolves completely in water is electrically neutral has non-polar regions

has polar regions and has non-polar regions

A base will release ______ ions when dissolved in water.

hydroxide

Matter is anything that has _________and occupies __________.

mass space

Anything that contains mass and occupies space is called

matter

pH is defined as the ________________ ____________________to the base 10 of the ____________ ion concentration.

negative logarithm hydrogen

There are ____ type(s) of atoms that can be found in a single element.

one

An atom's atomic number is based on the number of _________ it contains. In an atom that is not in a chemical reaction, the number of protons equals the number of __________

protons electrons

Substances dissolved in liquid are known as solvents. micelles. microbes. solutes.

solutes

A liquid that can dissolve substances is known as a(n)

solvent

Water, with the chemical formula H2O, contains ____ hydrogen atom(s) and ______oxygen atom(s).

two hydrogen atoms and one oxygen atom

In a(n) ______ reaction, water is used to break apart another molecule

hydrolysis

chemical _______ is reached when the rate of the forward reaction is equal to the rate of the reverse reaction.

equilibrium

When water is heated, the rate at which _______ bonds break increases, and water molecules are converted to the ______ state.

hydrogen gaseous

There are ___________ type(s) of atoms that can be found in a single element.

one

By mass, the most abundant element in living organisms is: carbon water hydrogen oxygen

oxygen

What determines whether a covalent bond is polar or nonpolar? ratio of neutrons to protons in each atom temperature of the solution electronegativity of the atoms involved in the bond time since the bond has formed

electronegativity of the atoms involved in the bond

True or false: Molecules that contain covalent bonds are rigid, inflexible structures.

false

Which types of chemical bonds are easily broken in water? Polar covalent bonds Nonpolar covalent bonds Ionic bonds Hydrogen bonds

ionic bonds and hydrogen bonds

The ______ of a solution is the negative base 10 logarithm of the H+ concentration of the solution.

pH

he ______ of a solution is the negative base 10 logarithm of the H+ concentration of the solution. equilibrium constant pH heat of vaporization heat capacity

pH

Why are atoms likely to share electrons? Because they contain seven or fewer total electrons. Because they are considered a noble gas. Because they have unfilled outer valence shells. Because they have a high electronegativity. Because they are considered an isotope.

Because they have unfilled outer valence shells.

Why are atoms likely to share electrons? Because they have a high electronegativity. Because they contain seven or fewer total electrons. Because they are considered a noble gas. Because they have unfilled outer valence shells. Because they are considered an isotope.

Because they have unfilled outer valence shells.

Which of the following best describes a contemporary model of electron movement within atoms? Electrons all occupy the same orbital. Electrons move in orbitals, although their exact location cannot be precisely predicted in these orbitals. Electrons move in very discrete, defined paths. Electrons move in different patterns depending on the number of atoms in the elements.

Electrons move in orbitals, although their exact location cannot be precisely predicted in these orbitals.

Which of the following are common features of chemical reactions? Select all that apply. Chemical reactions cease when they reach equilibrium. Many chemical reactions that occur in cells require catalysts. Chemical reactions require a source of energy. Many chemical reactions in living organisms take place in a watery environment. Chemical reactions proceed toward equilibrium.

Many chemical reactions that occur in cells require catalysts. Chemical reactions require a source of energy. Many chemical reactions in living organisms take place in a watery environment. Chemical reactions proceed toward equilibrium.

Which of the following statements are true of a polar covalent bond? Electrons are transferred completely from one atom to the other. The atoms in the bond differ in electronegativity. The two atoms in the bond share the electrons unequally. The shared electrons are equidistant between the nuclei of the two atoms. The atoms in the bond have the same electronegativity. The electrons are closer to the nucleus of the atom with lower electronegativity.

The two atoms in the bond share the electrons unequally The atoms in the bond differ in electronegativity

Molecules with covalent bonds: cannot change shape without breaking covalent bonds are flexible within certain limits are rigid at all times

are flexible within certain limits

The fundamental unit of matter is the molecules. cell. atom. nucleus.

atom

Matter is composed of functional units called _________, two or more of which, when bonded together, form a _________

atoms molecules

Hydrolysis reactions: break apart molecules via water create molecules via the loss of water create molecules via the loss of a smaller molecule

break apart molecules via water

In a chemical reaction, if there is no longer a change in the concentration of reactants and products, then all energy in the system has been expended. all reactants have become products. catalysis has ended. equilibrium has been reached.

equilibrium has been reached

Atoms tend to be most stable when their outer shells are ___________; this can be accomplished by gaining, losing, or sharing _______________.

full electrons

Electronegativity differences between atoms dictate the polarity of molecules by: ensuring that all atoms in a molecule are electrically neutral making sure electrons are shared equally among atoms in a molecule making sure only atoms of certain periods on the periodic table bond with each other influencing whether covalent bonds are polar or nonpolar

influencing whether covalent bonds are polar or nonpolar

A covalent bond is one in which a pair of electrons: dissociate from the nucleus is shared between two atoms is transferred from one atom to another to fill an outer valence shell

is shared between two atoms

A covalent bond is one in which a pair of electrons: is transferred from one atom to another to fill an outer valence shell is shared between two atoms dissociate from the nucleus

is shared between two atoms

Which component of humans has the greatest percent of water? Lungs Bones Blood Brain

lungs

A(n) ______ bond is formed when two atoms of different electronegativities share electrons. nonpolar covalent hydrogen ionic polar covalent

polar covalent

A(n) ______ bond is formed when two atoms of different electronegativities share electrons. nonpolar covalent polar covalent hydrogen ionic

polar covalent

The chemical formula of glucose is C6H12O6. How many oxygen atoms are in one molecule of glucose? Include just the number in your answer. 6 2 two twelve six 12

six, 6