chemical principles

8/3/2019 Chemical Principles

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BIO205 - Ch 2 - Chemical Principles - RioSalado - AZ

Question Answer

Isotopes Atoms w/different number of neutrons -Ex: 16/8O, 17/8O, 18/8O

Chemical properties of atoms are largly a function of

__.

Number of electrons in outermost

electron shell.

ValenceValence Combining capacity of atom -number of missing electrons in outermost

electron shell - "bonding capacity".

CompoundA molecule containing at least 2 different

kinds of atoms.

Atomic number Number of protons in nucleus

Mass number Total number of protons & neutrons

Chemical bonds Atoms sharing electrons

First shell Hold 2 electrons (1 orbital)

Second shell Holds 8 electrons (4 orbitals)

Third shell Holds 18 electrons (9 orbitals)

Molecules held together because?

The valence electrons of the combining

atoms form attractive forces

(chemicalbonds) between atomic nuclei.

Example of weaker ionic bond inimmune system.

Antigen-antibody reaction in which

antibodies combine with antigens to

combat infection.

Cations

An atom where outer electron shell is less

than 1/2 filled & will lose electrons toform positive ions - K+, Ca2+, Na+

Anions

Atom with more than 1/2 filled outer

electron shell will gain electrons & formnegative ions - I-, Cl-, S2-

Ion Atom that has gained or lost an electron
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& carries + or _ charge. H+ = Hydrogen

ion

Covalent bond

When atoms share one or more pairs ofelectrons - single stronger than ionic -

more common than ionic in organisms(H-H).

Ionic bond2 ions held together by opposite charges -when atoms have gained or lost outer

electrons - Ex: NaCl

Double Covalent Bond Two atoms sharing 2 electron pairs

Triple Covalent Bond Sharing 3 electron pairs

Polar covalent bond When 2 atoms don't share electronsequally - electronegative - water

molecules is example.

Hydrogen bond

Weak attraction formed betweencovalently bound hydrogen atom & an

electronegative atom - DNA is example -

holds 2 nucleotide strands together.

SolventIons & polar molecules easily dissolve in

it.

Sphere of hydrationClustering of water molecules around asolute - multiple ions dispersed in a fluid.

ATP Adenosine Triphosphate

DNA

Deoxyribonucleic acid - made 4 kinds of

deoxyribonucleotides - adenine, guanine,

thymine, cytosine. Base-pairing - thesequence of bases encodes heritable

information.

RNA

Ribonucleic acids - made of 4ribonucleotide monomers - uracil,adenine, guanine, & cytosine - How cell

retrieves & uses genetic info in DNA to

build proteins.

Hydrogen & carbon form __ bond quite easy because

__.

Covalent - their outer electron shells are

half-filled


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Covalent bonds are formed by __ electrons, while

ionic are formed by __ between atoms that have lost

or gained electrons.

sharing-attraction (become + or -

charged).

__ are weak but do serve as bridges between different

molecules or between various portions of samemolecule.

hydrogen bonds

In a molecule of water, all the electrons tend to becloser to the __ nucleus.

oxygen

Elements most frequently involved in hydrogen bond. oxygen & nitrogen

molecular weightSum of the atomic weights of all its

atoms.

One __ of a substance is its molecular weight ingrams. mole - ex: 1 mole of H2O = 18g[(2x1)+16]

Chemical energyChange of energy whenever bonds are

formed/broken during chemical reaction.

Chemical reaction that absorbs more energy than

released.Endergonic reaction

Chemical reaction that releases more energy than

absorbed.Exergonic reaction

Synthesis reactionWhen 2 or more atoms/ions/moleculescombine into larger molecules - "new

bonds formed" A+B=AB

Combining substances in reaction. reactants

Pathways of synthesis reaction in living organisms are

__.anabolic (anabolism)

2 examples of anabolism(1) combining of sugar molecules to form

starch & (2) amino acids to form proteins

Decomposition Reaction

bonds are broken - larger molecules split

into smaller - AB=A + B = catabolism in

living organisms.

2 examples of catabolism (1) breakdown of sucrose (table sugar)intoglucose& fructose during digestion,

(2) bacterial
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decomposition/bioremediation.

Inorganic compounds lack __.carbon - structurally simple - water,

oxygen, CO2, salts, acids, bases, etc.

What 2 elements are always fround in organiccompounds?

Carbon & hydrogen - structurallycomplete.

Most common bonds in organic compounds.Covalent bonds - atoms sharing one or

more pairs of electrons.

__ is the medium for most chemical reactions. water

The total charge of H2O molecule is __ but oxygen

retion __ and hydrogen.neutral, negative, positive

Every H2O molecule can form __ hydrogen bondswith nearby molecules. 4

solventDissolving medium - ex: water due to

polarity

dissociationSeparation into individual molecules inwater.

soluteA substance dissolved in another

substance

Polarity of H2O facilitates splitting & rejoining of __& __ ions.

hydrogen (H+) & hydroxide (OH-)

What protects cell from temperature fluctuations? Hydrogen bonds of water

ionizationBreaking apart (dissociation) into ions -

acids & bases

An __ dissociates into 1 or more H+ (cations) ions &1 or more negative ions (anions).

acid - proton (H+) donor

A __ dissociates into 1 or more H+ (cations) ions plusnegative charged hydroxide (OH-) that can accept

protons.

base - proton (H+) acceptor

pH measures?Amount of H+ in solution - "potential of

hydrogen"

Fungi tolerate __ conditions & prokaryotes __. acidic - alkaline


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isomer

2 molecules with same chemical formula,

but different structures & properties - ex:

glucose & fructose

carbohydrates

Contain an aldehyde or a ketone group,

and one or more hydroxyl groups

lipids mainly hydrocarbon

proteinsAre one or more polypeptide chains withas many as several thousand covalently

linked amino acids.

nucleic acids (nucleotides)

Chains of units that each consists of a 5-

carbon sugar, phosphate, & a nitrogen-containing base

waxes

Have long-chain fatty acids tightly

packed & bonded to long-chain alchols orcarbon rings

sterols lipids w/no fatty acids - Cholesterol

Amino acid

Small organic compounds with amino

group, carboxyl group, a hydrogen atom,& its R group. Used in constructing

proteins.

Peptide bond Bonds formed in polypeptide chains

Polypeptide chain 3 or more amino acids

PhosphateIn nucleotides (ATP), DNA, RNA - manyproteins - phospholipids. Water soluble -

acidic.

Sulfhydrl-SH - In amino acid cystine - helpsstabolize protein structure - disulfide

bridges.

Monomers Subunits of larger molecules

PolymersLarge organic molecule containing

subunits.

Hydroxyl -OH, In alcohols (amino acids, sugars)

water soluble - easy place to split or join
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molecules.

Methyl Fatty acid chains - insoluable in water

Carbonyl

In sugars, amino acids, nucleotides -

water soluable (aldehyde & ketone) -prone to electron transfers.

Carboxyl

In amino acids, fatty acids, water

soluable - highly polar - acts as acids -releases H+

AminoIn amino acids & nucleotides - base -

accepts H+ - water soluble

monosaccharides/oligosaccharide/polysaccharidesSimple carb/short chain sugar/"complex

carbohydrates"

Lipids

Nonpolar hydrocarbons - don't dissolve in

water - mix with other nonpolar

substances

fatsLipids w/1, 2, or 3 fatty acid tails -

from glycerolmolecule.

Fatty acidStarts as carboxyl group attached to

carbon atoms

Unsaturated fatty acid Contain one or more double covalentbonds

Saturated fatty acid Single bonds only

Neutral fatsTriglycerides - 3 fatty acid tails & 1glycerol head - butter, lard, vegetable

oils.

Organic compoundsMolecules that contain carbon and at

least 1 hydrogen

Hydrocarbons

Consist only of hydrogen atoms

covalently bonded to carbon - gasoline,

fossil fuels

Functional groupsOrganic compounds which are particularatoms or clusters of atoms covalently

bonded to carbon.
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