Chapter 2: The Chemistry of life Flashcards
What is matter?
anything that takes up space and has mass, can exist in three forms:
solid, liquid, and gas.
what is an element?
chemical substance whose atoms all have the same # of protons
How many elements are present and needed for life?
- Bulk Elements (99% of your body):
CHNOPS- Form majority of elements found in living organisms. - Trace Elements: an element that is still required in nature but only in small amounts.
What is atomic mass, and its unit of measurement?
is the sum of protons and neutrons in the nucleus. The mass of N and P are almost identical and are expressed in a U.O.M called Dalton.
What is the size of an electron in comparison to protons?
much smaller, 1/2000 the mass of a proton so it doesn’t contribute much to an atoms mass.
What is a radioactive isotope?
is an isotope that is very unstable and radioactive whose nucleus decays over time, giving off particles and energy.
What are some uses of radioactive isotopes?
could be used as tracers to follow chemicals as they undergo chemical changes in an organism.
Why are radioactive isotopes useful as tracers in research?
organisms can’t distinguish between normal isotopes and radioactive isotopes, and they would take them in naturally. As a result, researchers can use special scanning devices to detect these isotopes in the body.
What is an electron shell and what is an orbital?
an electron shell is a shell around the nucleus where electrons are to be found. # of shells depends on the number of electrons.
an orbital is a region on an electron shell where electrons are likely to be found, each orbital can hold two electrons.( the electrons don’t pair up until all orbitals have at least one electron)
What are chemical bonds?
when atoms with incomplete shells interact with one another to either give up, accept or share electrons so that both atoms are satisfied. (leads to stability). The attractions that hold these atoms together for them to interact are called chemical bonds.
What is the valence or bonding capacity of an atom?
the number of covalent bonds an atom can form, which is dependent on how many electrons are needed to fill the outer shell.
what are covalent bonds, and what decides what type of bonds are formed?
a type of bond in which electrons are shared as a result of the atoms having relatively similar electronegativities.
What is the difference between polar covalent bonds and non-polar covalent bonds?
Polar CB: Opposite, unequal sharing of electrons. (greatly differing electronegativities)
Non-polar CB: Equal sharing of electrons. (relatively similar electronegativities)
What is meant by polar?
refers to the separation of charges within a molecule due to an unequal sharing of electrons between atoms. Polar molecules have a positive and negative end.
What is an ion?
an atom or a molecule that has gained or lost one or more of its electrons.
Cations- Lost electrons (+)
Anions- Gained electrons (-)
What are hydrogen bonds?
a type of weak bond in which:
1. a hydrogen atom is bonded to a electronegative atom causing it be slightly positive.
2. Hydrogen bonding is enables after the covalent bind is formed and the H+ atom is attracted to other electronegative atoms (-)
Why are hydrogen bonds considered to be weak?
because unlike ionic and covalent bonds, they are attractions between a slightly (-) and (+) charge than the actual sharing or transfer of electrons (they are easily broken and reformed)
What are partial charges?
due to unequal sharing of electrons rather than the complete transfer, they don’t represent a full transfer and therefore are partial charges
What is a chemical reaction?
making/breaking of chemical bonds, leads to changes in composition, rearranging matter, not creating or destroying it.
Explain the following properties of water:
1. Cohesion:
2. Adhesion:
3. Surface tension:
- tendency of molecules of the same kind to stick together
ex- raindrop falling on a surface and collecting other rain drops in its path. - The attraction between different kinds of molecules.
Ex- water’s ability to stick other substances and surfaces - a measure of how difficult it is to stretch or break the surface of a liquid.
Why does water have a high surface tension?
due to the hydrogen bonds of the surface molecules, as a result of the accumulation of hydrogen bonds at the surface of water and the tight packing of these molecules.
What are the properties of water a result of?
Cohesion and adhesion are emergent properties as a result of the water molecule itself, whereas other properties such as surface tension, high temp. resistance, etc., are a result of the hydrogen bonding of water molecules with each other.
Define the following.
1. thermal energy
2. heat
3. Temperature
- kinetic energy due to the random motion of atoms/molecules.
- the thermal energy in the transfer from one body of matter to another.
- measures the intensity of heat- average speed of molecules in a body of matter.
Why does water have a high temperature resistance and how does the process of heating water go?
as a result of hydrogen bonds, which is why water takes longer to heat up. the reason for this is because the heat is first used to break the hydrogen bonds before it can be used to actually heat up the water, only then can the water molecules can start moving and a as result heat up.
What happens to heat as hydrogen bonds are formed and broken?
as hydrogen bonds form, heat is released, and as hydrogen bonds break, heat is absorbed.
What is less dense, water as a liquid or as a solid, and what is the reason behind the density?
water is less dense as a solid than as a liquid as a result of hydrogen bonds. The freezing of water causes each molecule to form HB with its neighbors make them stable and capable of floating as ice.
Define the following:
1. Solution:
2. Aqueous Solution:
- a liquid consisting of a uniform mixture of 2 or more substances.
- a solution in which water is the solvent.
What makes water a universal solvent:
is its polarity, where h+ atoms and the o- atoms separate and attract to the opposite polar regions of the introduced compound causing it to dissolve.
Define the following:
1. Acid:
2. Base:
3. PH scale:
- a substance that donates h+ to a solution
- a substance that reduces or removes hydrogen ions from a solution.
- a scale used to describe how acidic or basic a solution is. (stands for potential for hydrogen)
Briefly describe the PH scale?
0-6- Acidic: meaning a higher concertation of hydrogen ions than hydroxide ions.
7- Neutral - PH inside most cells
8-14- Basic: higher concentration of hydroxide ions than hydrogen ions.
NOTE: Each ph scale represents a 10 fold change.
Ph2-10
ph3-100
How can your body maintain a relatively constant PH in your cells and blood?
Biological fluids contain buffers, which are substances that minmizie change in PH. They do so by accepting H+ when it is in excess and by donating it when it is depleted.
