PHYSIO CH. 2 REVIEW QUESTIONS

nitrogen has an atomic number of 7. how many electron shells does it likely have?

2

which of the following is a molecule, but NOT a compound? a.H2O b. 2H c. H2 d. H+

H2

Ty is 3 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

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 4 electrons in it valence shell. according to the octet rule, it will readily participate in chemical reactions that result in its valence shell having 8 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.

uracil ___________. a. contains nitrogen b. is a pyrimidine c. is found in RNA d. all of the above

all of the above

which of the following is a functional group that is part of a building block of proteins? a. phosphate b. adenine c. amino d. ribose

amino

when an atom donates an electron to another atom, it becomes __________.

an ion

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

atom

_____________ reactions release energy

catabolic, exergonic, and decomposition

which of the following statements about chemical bonds is true? a. covalent bonds are stronger than ionic bonds b. hydrogen bonds occur between two atoms of hydrogen c. bonding readily occurs between nonpolar and polar molecules d. a molecule of water is unlikely to bond with an ion

covalent bonds are stronger than ionic bonds

AB ---> A + B is a general notation for a _______________ reaction

decomposition

in DNA, nucleotide bonding forms a compound with a characteristic shape known as a(n) ________________.

double helix

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

glucose

which of the following combinations of atoms is most likely to result in a chemical reaction? a. hydrogen and hydrogen b. hydrogen and helium c. helium and helium d. neon and helium

hydrogen and hydrogen

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 6 electrons in its valence shell. neither donating or 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.

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 2 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.

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

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

nucleic acids

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

salt

which of the following is most likely to be found evenly distributed in water in a homogeneous solution? a. sodium ions and chloride ions b. NaCl molecules c. salt crystals d. red blood cells

sodium ions and chloride ions

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

specificity

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 ________________.

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

oxygen, whose atomic number is 8, has 3 stable isotopes: 16O, 17O, and 18O. explain what this means in terms of the number of protons and neutrons.

the atomic number of an element is the number of protons in an isotope. the number of neutrons is the difference between the mass and the atomic number. 16= 8 protons + 8 neutrons 17= 8 protons + 9 neutrons 18= 8 protons + 10 neutrons

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-- and electron that can be "donated" in a chemical reaction with another atom. what is the meaning of a mass number shown in parenthesis?

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

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

dietary fats are digested and absorbed with the help of enzymes before getting released into the bloodstream as bigger particles cannot be absorbed. these fats are made of single fatty acid and three fatty acid chains bonded to a single molecule named glycerol. fats can be harmful as well as beneficial. saturated and trans fat are harmful dietary fat whereas mono and poly saturated fats are beneficial

a phospholipid ____________. a. has both polar and nonpolar regions b. is made up of a triglyceride bonded to a phosphate group c. is a building block of ATP d. can donate both cations and anions in solution

is made up of a triglyceride bonded to a phosphate group

AB + CD ---> AD + BE is this a legitimate example of an exchange reaction? why or why not?

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.

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 is acidic. when eli drank the bottle of lemon juice it made its blood too acidic which made his respiratory system compensate for the blood acidity to increase respiration but it was not enough. therefore, the immediate action of the ER was to administer the bicarbonate solution intravenously to counteract the acidity of the blood since bicarbonate is an alkaline solution

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.

what happens to the charged electroscope when a conductor is moved between its plastic sheets, and why?

nothing. in the example, a pen was used. the electrons in the pen did not change the plastic sheets on the electroscope because the plastic acted as an insulator.

CH4 is methane. this compound is ____________.

organic

together, just four elements make up more than 95% of the body's mass. these include ______________________.

oxygen, carbon, hydrogen, and nitrogen

a molecule of ammonia contains one atom of nitrogen and three atoms of hydrogen. these are linked with ___________.

polar covalent bonds

C6H12O6 is the chemical formula for __________

polymer of carbohydrate

the energy stored in a foot of snow on a steep roof is _________.

potential energy

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?

powder and liquid detergents have more enzymes and surfactants that work on grease and slime on the clothes. it is also easier for the molecules of the powder and liquid soaps to pay its role as nonionic surfactants due to more freedom of its movement than that of a solid bar of soap.

the characteristic that gives an element its distinctive properties is its number of _________________.

protons

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

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

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.