chapter 2

Explain why CH4 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.

Could two atoms of oxygen engage in ionic bonding? Why or why not?

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.

f 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.

about electrical energy and the attraction/repulsion of charges. What happens to the charged electroscope when a conductor is moved between its plastic sheets, and why?

The plastic sheets jump to the nail (the conductor), because the conductor takes on electrons from the electroscope, reducing the repellant force of the two sheets.

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.

deoxyribonucleic acid (DNA)

deoxyribose-containing nucleotide that stores genetic information

hydrogen bond

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

suspension

liqued mixture in which partticles distributed int he liquid settle out overt ime

pH

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

oxygen , who atomic number is eight, has three stable isotopes 16), 17) and 18 O , explain what this means in terms of the number of protons and neutrons

oxygen has eight protons. in its mosdt abundant stable form, it has eight neutrons, too, for a mass number of 16. in contrast 17O has nine neutrons and 18 O has 10 neutrons

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 compound

substance that does not contain both carbon and hydrogren

molecule

two or more atoms covalently bonded tgoether

synthesis reaction

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

matter

grain of sand to a star

monosaccharide

monomer of carbohydrate; also known as simple sugar

exchange reaction

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

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.

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.

when you do a load of laundry, why do you knot just drop a bar of soap into the washing machine. why liquid or prowder

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.

phospholipid

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

activation energy

amount of energy greater than the energy contained in the reactats, which must be overcome for a rection 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

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 blocks of proteins; characteriszed by an amino and carboxyl functional groups and a vairable 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, therby 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

protein

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

carbohydrate

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

nucleotide

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

base

compoudn that accepts hydrogen ions (H+) in solution

poly saccharide

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

acid

compound that releases hydrogran ions (H+) in solution

peptide bond

covalent bond formed by dehydration synthesis between two amino acids

disulfide bond

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

bond

electrical force linking atoms

kinective energy

energy that matter possess 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 borken

proton

heavy subatomic particle having a positve charge and found int he atom's nucleus

neutron

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

solution

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

maceomolecule

large molecule formed by covalent bonding

triglycerdie

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

prostaglandin

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

colloid

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

magnesium is an important element in the human body, especially in bones, Magnesiums atomic number is 12 it is stable or reactive? why? if it were to react with another atom, would it be more likely to acecpt 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

polar molecular

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

pruine

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

pyrimidine

nitrogen-containinng base with a single ring stcuture; cytosine, thiamine, and uracil

AB + CD -> AD + BE

not an legitimat exchange reaction- components of thr eactants are identical to the componenets of the roducts. A component present among the reactants cannot disappear, not can a component not present in the reactants suddently appear in the products

adenosine triphosphate (ATP)

nucleutide containing ribode 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

product

one of more substances produced by a chemical reaction

isotope

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

disaccharide

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

matter

physical substance, that which occupies space and has mass

enzyme

protein or RNA that catalyzses chemical reactions

substrate

reactant in an enzymatic reaction

ribonucleic acid (RNA)

ribose containing nucleotide that helps manifest the genetic code as protein

atom

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

buffer

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

potential energy

stored energy matter possess becasue of the positioning of strucutre of its componenets

electron

subatomic particle having a negative charge and nearly no mass; found orbiting the atoms nucleus

inorganic compound

substance that does not contain mboth carbon and hydrogren

catalyst

substance that increases the rate of c chemical reaction without iself being changed in the process

mass number

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

In the periodic table of the elements, elements in a single column have the same number of electrons that can participate in a chemical reaction. These electrons are known as "valence electrons." For example, the elements in the first column all have a single valence electron—an electron that can be "donated" in a chemical reaction with another atom. What is the meaning of a mass number shown in parentheses?

the mass number is the total number of protons and neutrons in the nueclus of an atom

functional group

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

reactant

one or more substances that enter into the reaction

steriod

or sterol/ lipid compound composed of foud hydrocarbon rings bondded to a variety of other atoms and molecules

valence shell

outermost electron shell of an atom

observe the formation of a disachharide. what happens when water encounters a glycosidic bond

the water hydrolyses, or breaks,the glycosidic bond, forming two monosaccharides

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 cannnot make elements, so it is helpful to have them in consumables

decomposition reaction

type of catabolic reaciton in which one or more bonds within a larger molecule are borke, restuling in the release of smaller molecules or atoms

radioactive isotope

unstalbe, having isotope that gives off subatomic particles, or electromagnetic energy, as it decays, also called radioisotopes