Chapter 2: Chemical Level Of Organization Flashcards
How many chemical elements are present in your body?
26
What are the 4 major elements that constitute 96% of your body mass?
O, C, H, N
What are the 8 elements that constitute 3.6% of your body mass?
Ca, P, K, S, Cl, Mg, Fe, and Na
How many trace elements are in your body?
14
What is the nucleus?
The dense core of an atom
How many electrons do the first 3 shells hold?
First holds 2, second holds 8 and third holds 18
Why is an atom usually electrically neutral?
Because the number of protons equals the number of electrons
What is the atomic number and atomic mass?
Atomic number is the number of protons. Atomic mass is the number of protons + neutrons
What are isotopes?
Atoms that have different numbers of neutrons so have different mass numbers
What is a stable isotope?
It’s nuclear structure doesn’t change over time.
What’s a radioactive isotope? Give some examples
Unstable. Their nuclei decay into stable configuration (H-3, C-14, O-15, O-19)
Explain how radioactive isotopes can be harmful
They can break apart molecules thus posing a threat to human body by producing tissue damage or causing various types of cancer
Name some benefits of radioactive isotopes
For diagnostic or treatment purposes. Used as tracers to follow movement of certain substances through the body. Iodine-131 detects cancer of thyroid gland. Cesium-137 used to treat advanced cervical cancer.
What is the Atomic Mass?
Average mass of all its naturally occurring isotopes. Measured in Daltons and is usually close to the mass number
What is a Dalton?
A unit for measure the mass of atoms and their subatomic particles
What is an ion?
An atom that is electrically charged because it gives up or gains an electron… have a positive or negative charge
Define ionization
Process of giving up or gaining an electron
What is a molecule?
When 2 or more atoms share electrons
What is included in a molecular formula?
The elements and the number of atoms of each element that make up a molecule (O2… molecule contains 2 atoms of oxygen)
H2O… one oxygen atom shares electrons with 2 hydrogen atoms
What is a compound?
A substance that contains atoms of 2 or more different elements (H2O and NaCl)
What is a Free Radical?
An atoms / group of atoms with an unpaired electron in its outer shell… highly unstable and reactive and destructible to nearby molecules
How does a free radical become stable?
Either by giving up the unpaired electron or by gaining an electron from another molecule
What are some sources of free radicals and what are some illnesses that may be associated with free radicals?
Sources: UV from sun, X-rays, some reactions occur during normal metabolic processes.
Diseases: Cancer, atherosclerosis, Alzheimer’s, DM, cataracts, rheumatoid arthritis, aging
Why are antioxidants important?
They inactivate oxygen-derived free radicals. So may slow down aging!
What atoms are most likely to bind with others?
Atoms who do not have a filled valence shell
What is the Octet Rule?
Explains why atoms act in predictable ways. One atom will be more likely to bind with another if doing say will leave both of them with 8 electrons in its valence shell
What are the 3 types of chemical bonds?
Ionic, covalent, and hydrogen
What is an ionic bond?
A force of attraction that holds together 2 ions with opposite charges. Ie Na+ and Cl- create NaCl (sodium chloride). When an atom of sodium donates its sole valence electron to an atom of chlorine the resulting positive and negative charges pull both ions tightly close together and an ionic bond is formed.
What’s an electrolyte?
Ionic compound that breaks apart into positive and negative ions in a solution… the solutions conduct a negative current
What’s a covalent bond?
Two or more atoms SHARE electrons rather than gaining or losing them. The larger the number of electron pairs share between the 2 atoms the stronger the bonds. Can be single, double or tripple covalent bonds
What’s a non-polar covalent bond?
Sharing of electrons between 2 atoms is equal. One atom does not attract the shared electrons more strongly. Such as all bonds between 2 identical atoms.
What is a polar covalent bond?
Sharing of electrons betwee 2 atoms is UNEQUAL. Nucleus of one atom attracts the shared electrons more strongly than the nucleus of the other atom. Resulting molecule has a negative charge near the atom that attracts electrons more strongly (this atom has electronegativity… power to attract electrons to itself). At least one other atom in the molecule will have a positive charge. H2O… oxygen atom has greater electronegativity
What are hydrogen bonds?
Forms when a H atom with a partial + charge attracts the partial negative charge of neighbouring electronegative atoms… usually O or N atoms. . Results from attraction of oppositely charged parts of molecules rather than from sharing electrons (covalent) or loss/gain of electrons (ionic). Weakest bond. Can’t bind atoms into molecules.
What is cohesion?
Hydrogen bonds that link neighbouring water molecules give water considerable cohesion which is the tendency of like particles to stay together. Cohesion of water molecules creates high SURFACE TENSION, a measure of the difficulty of stretching or breaking the surface of a liquid. The boundary between water and air means that surface tension is very high. Hydrogen bonds, when many act together, provide lots of strength and stability. When we breathe, each inhalation must have enough force to overcome the opposing effect of surface tension as the air sacs stretch and enlarge when taking in air
What is a acid?
A substance that dissociates (separate into ions and surrounded by water molecules) into one or more hydrogen ions (H+) and one or more anions. Acid is a proton donor because H+ is a single proton with a charge
What’s a base?
Dissociate into one or more hydroxide ions (COH-) and one or more cations. It’s a proton acceptor because it removes H+ from solution.
What is salt?
When dissolved in water it dissociates into cations and anions (neither of which is H+ or OH-). Salt like potassium chloride are electrolytes responsible for carrying electrical currets epseiclaly in nerve and muscle tissue. Acids and bases react with one another to form salts
What is the pH scale?
Expresses acidity and alkilinity. 0-14. Based on concentration of H+ per mole per L. More H+ ions, the more acidic. More OH- than H+ = basic. Higher numbers are basic.
What are buffer systems?
Convert strong acids and bases into weak acids and bases.
Strong acids/bases vs weak acids/bases?
Strong acids/bases ionize easily and contribute many H+ (or OH-) ions to solutions which can disrupt body’s metabolism. Weak acids/bases don’t ionize as much and contribute fewer H+ or OH- so have less affect on pH
What are buffers?
Chemical compounds that can convert strong acids/bases into weak ones by adding or removing protons (H+)
What is the carbonic acid - bicarbonate buffer system?
Carbonic acid (H2CO3) can act as a weak acid and the bicarbonate ions (HCO3) acts as a weak base. Compensates for an excess or shortage of H+. HCO3 is a weak base and compensates for an excess or shortage of H+. H2CO3 acts as a weak acid and provides the needed H+.
Why is carbon useful to living organisms?
Can form bonds with 1-1000 other carbon atoms to produce large molecules with different shapes. Useful for building body structures because the molecules are big and many don’t dissolve easily in water. 4 electrons in valence shell.
Define a Carbon Skeleton
Chain of C atoms in organic molecules
Define a hydrocarbon
Many carbons are bounded to H atoms
What are functional groups?
Other atoms/molecules bound to the hydrocarbon skeleton
What are some major functional groups of organic molecules?
Hydroxyl, sulfhydryl, carbonyl, carboxyl, ester, phosphate, amino acids
What are macromolecules?
Small organic molecules combined into very large molecules
What are Polymers?
A large molecule formed by the covalent bonding of many identical/similar small building block molecules called monomers. MACROMOLECULES are polymers. Two monomers are usually joined by dehydration synthesis
What are isomers?
MOlecules with the same molecular formula but different structures so have different chemical properties.
What are carbohydrates?
Includes sugars, glycogen, starches, cellulose. Source of chemical energy for generating ATP needed to drive metabolic processes. C, H and O are elements of carbohydrates. Ratio of H to O is 2:1.
What are the 3 main groups of carbohydrates?
Monosaccharides, disaccharides, and polysaccharides.
What are monosaccharides?
The monomers of carbohydrates. Contains 3-7 C atoms. End in “ose”. Prefix indicates the number of C atoms. Hexose glucose broken down to produce ATP.
What are disaccharides?
Molecule formed from the combination of 2 monosaccharides by dehydration synthesis. For example fructose and glucose cmbine to form the disaccharide sucrose. Disaccharides can be split into smaller simpler molecules by hydrolysis.
What are polysaccharides?
Contains hundreds of monosaccharides joined through dehydration syntheses. Usually insoluble in water. Glycogen is the main polysaccharide in the body (is made up of glucose monomers).