The chemical level of organization textbook questions

steroid

(also, sterol) lipid compound composed of four hydrocarbon rings bonded to a variety of other atoms and molecules

Explain why CH is one of the most common molecules found in nature. Are the bonds between the atoms ionic or covalent?

A carbon atom has four electrons in its valence shell. According to the octet rule, it will readily participate in chemical reactions that result in its valence shell having eight electrons. Hydrogen, with one electron, will complete its valence shell with two. Electron sharing between an atom of carbon and four atoms of hydrogen meets the requirements of all atoms. The bonds are covalent because the electrons are shared: although hydrogen often participates in ionic bonds, carbon does not because it is highly unlikely to donate or accept four electrons.

AB+CD→AD+BE Is this a legitimate example of an exchange reaction? Why or why not?

A. It is not. An exchange reaction might be AB+CD→AC+BD or AB+CD→AD+BC. In all chemical reactions, including exchange reactions, the components of the reactants are identical to the components of the products. A component present among the reactants cannot disappear, nor can a component not present in the reactants suddenly appear in the products.

Oxygen, whose atomic number is eight, has three stable isotopes: O, O, and O. Explain what this means in terms of the number of protons and neutrons.

A. Oxygen has eight protons. In its most abundant stable form, it has eight neutrons, too, for a mass number of 16. In contrast, O has nine neutrons, and O has 10 neutrons.

Once dietary fats are digested and absorbed, why can they not be released directly into the bloodstream?

All lipids are hydrophobic and unable to dissolve in the watery environment of blood. They are packaged into lipoproteins, whose outer protein envelope enables them to transport fats in the bloodstream.

reactions release energy.

Catabolic, exergonic, and decomposition

Which of the following is a molecule, but not a compound?

H2 (H20 ,2H,H+)

Could two atoms of oxygen engage in ionic bonding? Why or why not? A. Identical atoms have identical electronegativity and cannot form ion

Identical atoms have identical electronegativity and cannot form ionic bonds. Oxygen, for example, has six electrons in its valence shell. Neither donating nor accepting the valence shell electrons of the other will result in the oxygen atoms completing their valence shells. Two atoms of the same element always form covalent bonds.

The pH of lemon juice is 2, and the pH of orange juice is 4. Which of these is more acidic, and by how much? What does this mean?

Lemon juice is one hundred times more acidic than orange juice. This means that lemon juice has a one hundred-fold greater concentration of hydrogen ions.

During a party, Eli loses a bet and is forced to drink a bottle of lemon juice. Not long thereafter, he begins complaining of having difficulty breathing, and his friends take him to the local emergency room. There, he is given an intravenous solution of bicarbonate. Why?

Lemon juice, like any acid, releases hydrogen ions in solution. As excessive H enters the digestive tract and is absorbed into blood, Eli's blood pH falls below 7.35. Recall that bicarbonate is a buffer, a weak base that accepts hydrogen ions. By administering bicarbonate intravenously, the emergency department physician helps raise Eli's blood pH back toward neutral.

Magnesium is an important element in the human body, especially in bones. Magnesium's atomic number is 12. Is it stable or reactive? Why? If it were to react with another atom, would it be more likely to accept or to donate one or more electrons?

Magnesium's 12 electrons are distributed as follows: two in the first shell, eight in the second shell, and two in its valence shell. According to the octet rule, magnesium is unstable (reactive) because its valence shell has just two electrons. It is therefore likely to participate in chemical reactions in which it donates two electrons.

If the disaccharide maltose is formed from two glucose monosaccharides, which are hexose sugars, how many atoms of carbon, hydrogen, and oxygen does maltose contain and why?

Maltose contains 12 atoms of carbon, but only 22 atoms of hydrogen and 11 atoms of oxygen, because a molecule of water is removed during its formation via dehydration synthesis.

When you do a load of laundry, why do you not just drop a bar of soap into the washing machine? In other words, why is laundry detergent sold as a liquid or powder

Recall that the greater the surface area of the reactants, the more quickly and easily they will interact. It takes energy to separate particles of a substance. Powder and liquid laundry detergents, with relatively more surface area per unit, can quickly dissolve into their reactive components when added to the water.

The most abundant elements in the foods and beverages you consume are oxygen, carbon, hydrogen, and nitrogen. Why might having these elements in consumables be useful?

These four elements—oxygen, carbon, hydrogen, and nitrogen—together make up more than 95 percent of the mass of the human body, and the body cannot make elements, so it is helpful to have them in consumables.

Ty is three years old and as a result of a "stomach bug" has been vomiting for about 24 hours. His blood pH is 7.48. What does this mean?

Ty's blood is slightly alkaline.

In a hurry one day, you merely rinse your lunch dishes with water. As you are drying your salad bowl, you notice that it still has an oily film. Why was the water alone not effective in cleaning the bowl?

Water is a polar molecule. It has a region of weakly positive charge and a region of weakly negative charge. These regions are attracted to ions as well as to other polar molecules. Oils are nonpolar, and are repelled by water.

Phospholipids

a lipid compound in which a phosphate group is combined with a diglyceride

phosphorylation

addition of one or more phosphate groups to an organic compound

Which of the following is a functional group that is part of a building block of proteins?

amino

activation energy

amount of energy greater than the energy contained in the reactants, which must be overcome for a reaction to proceed

electron shell

area of space a given distance from an atom's nucleus in which electrons are grouped

periodic table of the elements

arrangement of the elements in a table according to their atomic number; elements having similar properties because of their electron arrangements compose columns in the table, while elements having the same number of valence shells compose rows in the table

The smallest unit of an element that still retains the distinctive behavior of that element is an

atom

anion

atom with a negative charge

cation

atom with a positive charge

ion

atom with an overall positive or negative charge

ionic bond

attraction between an anion and a cation

amino acid

building block of proteins; characterized by an amino and carboxyl functional groups and a variable side-chain.

Denaturation

change in the structure of a molecule through physical or chemical means

covalent bond

chemical bond in which two atoms share electrons, thereby completing their valence shells

lipid

class of nonpolar organic compounds built from hydrocarbons and distinguished by the fact that they are not soluble in water

Carbohydrates

class of organic compounds built from sugars, molecules containing carbon, hydrogen, and oxygen in a 1-2-1 ratio

nucleotide

class of organic compounds composed of one or more phosphate groups, a pentose sugar, and a base

protein

class of organic compounds that are composed of many amino acids linked together by peptide bonds

polysaccharide

compound consisting of more than two carbohydrate monomers bonded by dehydration synthesis via glycosidic bonds

base

compound that accepts hydrogen ions (H ) in solution

acid

compound that releases hydrogen ions (H ) in solution

uracil

contains nitrogen , is a pyrimidine , is found in RNA

peptide bond

covalent bond formed by dehydration synthesis between two amino acids

disulfide bond

covalent bond formed within a polypeptide between sulfide groups of sulfur-containing amino acids, for example, cysteine

Which of the following statements about chemical bonds is true?

covalent bonds are stronger than ionic bonds.

AB→A+B is a general notation for a(n) ________ reaction.

decompostion

deoxyribonucleic acid (DNA)

deoxyribose-containing nucleotide that stores genetic information

hydrogen bond

dipole-dipole bond in which a hydrogen atom covalently bonded to an electronegative atom is weakly attracted to a second electronegative atom

In DNA, nucleotide bonding forms a compound with a characteristic shape known as a(n) ____

double helix

bond

electrical force linking atoms

kinetic energy

energy that matter possesses because of its motion

chemical energy

form of energy that is absorbed as chemical bonds form, stored as they are maintained, and released as they are broken

What organic compound do brain cells primarily rely on for fuel?

glucose

functional group

group of atoms linked by strong covalent bonds that tends to behave as a distinct unit in chemical reactions with other atoms

A phospholipid

has both polar and nonpolar regions

proton

heavy subatomic particle having a positive charge and found in the atom's nucleus

neutron

heavy subatomic particle having no electrical charge and found in the atom's nucleus

C6 H12O6 is the chemical formula for a

hexose monosaccharide

Solution

homogeneous liquid mixture in which a solute is dissolved into molecules within a solvent

Which of the following combinations of atoms is most likely to result in a chemical reaction?

hydrogen and hydrogen

When an atom donates an electron to another atom, it becomes

ion

macromolecule

large molecule formed by covalent bonding

Triglycerides

lipid compound composed of a glycerol molecule bonded with three fatty acid chains

prostaglandin

lipid compound derived from fatty acid chains and important in regulating several body processes

suspension

liquid mixture in which particles distributed in the liquid settle out over time

colloid

liquid mixture in which the solute particles consist of clumps of molecules large enough to scatter light

polar molecule

molecule with regions that have opposite charges resulting from uneven numbers of electrons in the nuclei of the atoms participating in the covalent bond

monosaccharide

monomer of carbohydrate; also known as a simple sugar

On the periodic table of the elements, mercury (Hg) has an atomic number of 80 and a mass number of 200.59. It has seven stable isotopes. The most abundant of these probably have

more than 80 neutrons each

PH

negative logarithm of the hydrogen ion (H ) concentration of a solution

purine

nitrogen-containing base with a double ring structure; adenine and guanine

pyrimidine

nitrogen-containing base with a single ring structure; cytosine, thiamine, and uracil

A pentose sugar is a part of the monomer used to build which type of macromolecule?

nucleic acids

adenosine triphosphate (ATP)

nucleotide containing ribose and an adenine base that is essential in energy transfer

Concentration

number of particles within a given space

atomic number

number of protons in the nucleus of an atom

isotope

one of the variations of an element in which the number of neutrons differ from each other

product

one or more substances produced by a chemical reaction

Reactant

one or more substances that enter into the reaction

CH is methane. This compound is

organic

valence shell

outermost electron shell of an atom

Together, just four elements make up more than 95 percent of the body's mass. These include

oxygen, carbon, hydrogen, and nitrogen

Diasaccharide

pair of carbohydrate monomers bonded by dehydration synthesis via a glycosidic bond

matter

physical substance; that which occupies space and has mass

A molecule of ammonia contains one atom of nitrogen and three atoms of hydrogen. These are linked with

polar covalent bonds

The energy stored in a foot of snow on a steep roof is

potential energy

enzyme

protein or RNA that catalyzes chemical reactions

The characteristic that gives an element its distinctive properties is its number of

protons

ribonucleic acid (RNA)

ribose-containing nucleotide that helps manifest the genetic code as protein

Chewing a bite of bread mixes it with saliva and facilitates its chemical breakdown. This is most likely due to the fact that

saliva contains enzymes

A substance dissociates into K and Cl in solution. The substance is a(n) ________.

salt

A substance formed of crystals of equal numbers of cations and anions held together by ionic bonds is called a(n)

salt

atom

smallest unit of an element that retains the unique properties of that element

Which of the following is most likely to be found evenly distributed in water in a homogeneous solution?

sodium ions and chloride ions

buffer

solution containing a weak acid or a weak base that opposes wide fluctuations in the pH of body fluids

The ability of an enzyme's active sites to bind only substrates of compatible shape and charge is known as

specificity

potential energy

stored energy matter possesses because of the positioning or structure of its components

electron

subatomic particle having a negative charge and nearly no mass; found orbiting the atom's nucleus

compound

substance composed of two or more different elements joined by chemical bonds

element

substance that cannot be created or broken down by ordinary chemical means

organic

substance that contains both carbon and hydrogen

Inorganic

substance that does not contain both carbon and hydrogen

catalyst

substance that increases the rate of a chemical reaction without itself being changed in the process

substrate

substrate reactant in an enzymatic reaction

mass number

sum of the number of protons and neutrons in the nucleus of an atom

Jenny mixes up a batch of pancake batter, then stirs in some chocolate chips. As she is waiting for the first few pancakes to cook, she notices the chocolate chips sinking to the bottom of the clear glass mixing bowl. The chocolate-chip batter is an example of a

suspension

The bonding of calcium, phosphorus, and other elements produces mineral crystals that are found in bone. This is an example of a(n) ________ reaction.

synthesis

Nitrogen has an atomic number of seven. How many electron shells does it likely have?

two

molecule

two or more atoms covalently bonded together

synthesis reaction

type of anabolic reaction in which two or more atoms or molecules bond, resulting in the formation of a larger molecule

decomposition reaction

type of catabolic reaction in which one or more bonds within a larger molecule are broken, resulting in the release of smaller molecules or atoms

exchange reaction

type of chemical reaction in which bonds are both formed and broken, resulting in the transfer of components

radioactive isotope

unstable, heavy isotope that gives off subatomic particles, or electromagnetic energy, as it decays; also called radioisotopes