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