Chapter 2-4 Flashcards
Give an example of an overlap of chemicals and biology.
− Duroia hirsuta trees are known as “devil’s garden” due to the lack of other plants that surround them.
− It was discovered that ants living in these trees release a chemical known as formic acid into intruding plants to provide space for the Duroia hirsuta tree that serves as their home
What is matter?
Matter- anything that takes up space and has mass
What is an element? How many elements are there?
Element- a substance that cannot be broken down by a chemical reaction
• Chemists recognize 92 elements
What is a compound?
Compound- substance consisting of two or more different elements combined at a fixed ratio
• A compound has characteristics different than those of its elements
How many elements are essential to life?
25
Which elements make up 96% of all living matter?
Carbon Oxygen Hydrogen Nitrogen
What are trace elements and what is an example?
Trace elements- elements required by an organism in minute quantities (less than .01% body weight), iodine prevents goiter
List the trace elements.
Trace Elements: boron cobalt copper chromium fluoride iron iodine manganese molybdenum selenium silicon tin vanadium zinc
List the major minerals.
Elements that make up 4% of an organisms weight (major minerals): sodium potassium chloride calcium phosphorus magnesium sulfur (salty potato chips contain pretty much salt)
What is an atom?
Atom- the smallest unit of matter that still retains the properties of an element
What are subatomic particles?
Subatomic particles- protons (+), neutrons (0), electrons (-)
How are the subatomic particles structured in an atom?
Protons and neutrons are packed together in a tight core or atomic nucleus and electrons form a negative cloud around the nucleus
What units are used to compute the mass of an atom?
Daltons or atomic mass unit (amu) are used to compute the mass of an atom. One neutron or proton is about one Dalton or amu. (electrons are ignored when computing mass)
What is the atomic number?
Atomic Number- number of protons (if neutral this equals the number of electrons)
What is the mass number?
Mass Number- sum of protons and neutrons
What is atomic mass?
Atomic Mass- precise mass in Daltons
What is an isotope?
atoms with different amounts of neutrons
What is a radioactive isotope?
Radioactive Isotope- an isotopes in which the nucleus decays spontaneously giving off particles and energy (Carbon 14)
What occurs when a radioactive isotope lead to a change in the number of protons?
When the decay lead to a change in the number of protons it transforms to an atoms of a different element (radioactive carbon to nitrogen)
What are the uses and consequences of radioactive isotopes?
- PET scans use radioactive isotopes and are also used in dating fossils
- Radiation from decaying isotopes poses a hazard to life by damaging cellular molecules
Which subatomic particle is directly involved in reactions between atoms?
electrons
What is energy?
the capacity to cause change
What is potential energy?
energy that matter possesses because of its location or structure
How do electrons have potential energy?
Electrons of an atom have potential energy because of how they are arranged in relation to the nucleus- the more distant an electron is from the nucleus the greater its potential energy
What are electron shells?
Electrons are found in different electron shells- each with a characteristic distance and energy level
What occurs when an electron absorbs or loses energy?
- When an electron absorbs energy it moves to a shell farther out from the nucleus (light may excite an atom)
- When an electron loses energy it falls back to a shell closer to the nucleus and lost energy is usually released to the environment as heat
How many electrons can each shell hold?
• First electron shell can only hold 2 electrons and the second 8, and the third 8.
What is the chemical behavior of an atom most dependent on?
The chemical behavior of an atom depends mostly on the electrons in the outermost shell. Valence electrons and valence shell.
What is an atom with a full valence shell called?
• Helium, neon, and argon have full valence shells and are celled inert or inactive.
What is an orbital?
• Orbital- three dimensional space where an electron is found 90% of the time
> Such as s, p, and d
> S is spherical and P is dumbbell shaped
> No more than two electrons can occupy a single orbital
What are chemical bonds?
atoms sharing or transfer valence electrons
What is a covalent bond?
Single/ double?
Covalent Bond- the sharing of a pair of valence electrons by two atoms
• A single bond is a pair of shared electrons while a double bond is two pairs of shared electrons
What is valence?
Valence- the bonding capacity of an atom- usually equals the number of unpaired electrons required to complete the atoms outermost electron shells
What is electronegativity?
Electronegativity- the attraction of a particular kind of atom for the electron of a covalent bond
What is a non-polar covalent bond?
electrons are shared equally
What is a polar covalent bond? Give an example?
− Polar covalent bond- electrons shared unequally- water is polar
• Oxygen is more electronegative and is partially negative charged (-)
• Hydrogen is less electronegative and is partially positively charged (+)
What is an ionic bond?
Ionic Bond- transfer of electron from one atom to another- NaCl
What is an ion? And what are the two types?
Ion- a charged atom- charge can be found by protons-electrons
• Cation- positive charge
• Anion- negative charge
What are compounds formed by ionic bonds called?
Compounds formed by ionic bonds are called ionic compounds or salts. They aggregate and form crystals in nature.
How does the environment affect ionic bonds?
Environment affects ionic bonds. Dry salt crystals are strong, while salt crystals dissolved in water are weak
What is a hydrogen bond?
Hydrogen Bond- hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom H2O and NH3
What are Van Der Waals interactions?
−Electrons are not always symmetrically distributed and at any instant they accumulate by chance in one part of the molecule. This results in ever-changing regions of positive and negative charge that enable all atoms and molecules to stick to one another in van der Waals interactions.
Allow geckos to walk up walls
Why does molecule shape impact function?
− Molecular shape impacts function because only molecules with complementary shape can form weak bonds with each other.
What is a chemical reaction?
the making and breaking of chemical bonds
What are the component of a chemical reaction?
products and reactants
What is chemical equilibrium?
the point at which chemical reactions offset each other exactly
What is the photosynthesis reaction?
− 6 CO2 + 6 H2OC6H12O6 + 6 O2
4 reasons water is relevant.
- ¾ of Earth’s surface is submerged in water
- Water is the only common substance to exist on Earth in all three physical states of matter
- All life is tied to water.
- Humans need water and cells are 70-95% water.
Why is water polar?
uneven distribution of electrons
Oxygen is partial - and hydrogen is partially +
What type of bond does water form because of its polarity and when are they fragile?
Water forms hydrogen bonds. When water is in its liquid form the hydrogen bonds are very fragile.
What are the four emergent properties of water?
Cohesion, Moderation of temperature, Insulation of bodies of water by floating ice, solvent of life
What is cohesion and what does it contribute to?
- Cohesion- water molecules stick to themselves
• Contributes to the transport of water against gravity in plants
What is adhesion and what does it contribute to?
- Adhesion- the clinging of one substance to another
• Helps counter the downward pull of gravity
What is surface tension?
- Surface Tension- how difficult it is to stretch or break the surface of a liquid
How does waters surface tension compare to other liquids?
Water has higher surface tension than most other liquids
What is moderation of temperature?
Moderation of Temperature- water moderates air temperature by absorbing heat from air that is warmer and releasing the stored heat to air that is cooler.
Why is water effective at moderating temperature?
Water can absorb a large amount of heat and still slightly change its temp.
What is kinetic energy? How does a molecules kinetic energy increase?
• Kinetic Energy- energy of motion
The faster a molecule the greater its kinetic energy
What is heat?
a measure of the matters total kinetic energy due to the motion of its molecules (related to volume)
What is temperature?
average kinetic energy of molecules
What is a calorie? Kilocalorie?
- Calorie- the amount of heat it takes to raise the temperature of 1g of water by 1C
- Kilocalorie- the amount of heat it takes to raise the temperature of 1kg of water by 1C (calories on food packages)
What is a joule?
a unit of energy
What is specific heat and how is water’s specific heat compared to other molecules?
- Water has high specific heat. 1 calorie/g/C
* Specific heat- the amount of heat that must be absorbed or lost for one gram of that substance to change temp by 1C
Why does a calorie of heat cause a small change in waters temp?
A cal of heat causes a relatively small change in temp because much of the heat is used to disrupt hydrogen bonds before the water can begin moving faster
What is heat of vaporization and how is water’s compared to other molecules?
• Water has a high heat of vaporization- the quantity of heat a liquid must absorbs for 1g to be converted to gas.
What is evaporative cooling? What are two examples?
• As a liquid evaporates the surface of the liquid that remains behind cools down. This is known as evaporative cooling.
- Moderates the temp of large bodies of water
- Helps maintain homeostasis
How does water freeze?
• Water begins to freeze when molecules are not moving vigorously enough to break their hydrogen bonds so it turns into a crystalline lattice.
When is water more dense solid or liquid?
Water is less dense as a solid than a liquid
Why does the density of ice contribute to the amount of ice one the planet?
Since ice floats not as much water freezes because the liquid water becomes insulated by ice
What is the most effective solvent?
water
What is a solution? What are the components?
• Solution- a liquid that is a homogeneous mixture of two or more substances
Solvent- dissolving agent
Solute- substance that is dissolved
What is an aqueous solution?
water is the solvent
What is a hydration shell?
Sphere of water molecules around an ion
What is hydrophilic?
Substance with a
What is a hydration shell?
Hydration shell- sphere of water molecules around an ion
What is hydrophilic?
a substance with an affinity for water
What is a colloid?
stable suspension of particles in a liquid
What is hydrophobic?
substances that repel water (non ionic) and non polar)
What is molecular mass?
sum of the masses of all of the atoms in a molecule
What is a mole?
numer of molecules 6.02x10^23
What is molarity?
moles per liter
How are H+ and OH- molecules formed?
Occasionally a Hydrogen atom in a hydrogen bond shifts from one molecule to another forming an H+ and OH- molecule
What is an acid?
Acid- substance that increases the hydrogen ion concentration of a solution (HCl)
What is a base?
Base- reduces the hydrogen ion concentration of a solution
Which acid base reactions are reversible and which are not?
Weak acids and bases are reversible reactions while strong acids and bases completely dissociate
Explain why ph goes up to 14
The product of the H+ and OH- concentrations is a constant 10-14. (At 25 C)
What is the number of the pH representing?
pH of a solution is the negative logarithm (base 10) of the hydrogen ion concentration
pH delinces as _____ increases
H+ concentration
What are buffers?
- substances that minimize changes in the concentration of H+ or OH- in a solution
How do buffers work?
What is an example?
- They accept H+ ions when they are in excess and donate them when they have been depleted.
- Most buffer solution contain an acid and its corresponding base
- Carbonic acid H2CO3
What is acid precipitation?
rain/ snow lower than a pH of 5.2
What is the cause and effect of acid precipitation?
- Cause by the burning of fossil fuels forming sulfur and nitrous oxides
- Affects marine life and soil
How does carbon dioxide impact the environment?
- Carbon dioxide also causes the green house effect through layering in the atmosphere and is dissolved in the oceans forming carbonic acid.
• This affects the calcification of coral reefs because of lowered amounts of CO32-
How does carbon enter and travel through the biosphere?
Carbon enters the biosphere through the action of plants which use solar energy to transform atmospheric CO2 into the molecules of life. These molecules are passed along to animals that feed on plants
What accounts to the large diversity of biological molecules
carbon
What are the common ingredients of biological compounds?
Hydrogen, Oxygen, Nitrogen, Sulfur, and Phosphorus and carbon
What is organic chemistry?
study of organic compounds
How did organic chem originate?
the attempt to purify and improve the yield of food and medecine
What did Swedish chemist Jöns Jakob Berzelius do?
- Swedish chemist Jöns Jakob Berzelius made the distinction between organic and inorganic compounds.
What is vitalism?
- Vitalism- the belief in a life force outside the jurisdiction of physical and chemical laws
What did Friedrich Wohler do and when?
- 1828, Friedrich Wöhler attempted to make an inorganic salt ammonium cyanate but found he made urea instead.
What did Stanley Miller do and when?
1953, Stanley Miller used an experiment with a body of water that was vaporized, sparked, and then condensed. He found amino acids in his product supporting the idea that organic molecules may have been synthesized abiotically early on earth.
How did the view of organic chem shift?
Organic chemistry was shifted from vitalism to mechanism
What is mechanism?
- mechanism- the view that physical and natural laws govern all natural phenomena including the processes of life
What is the term for carbons valence?
tetravalence
What are three examples of tetravalent win carbon?
- Methane- CH4 is tetrahedraland has bond angles of 109.5
- Ethane- C2H6
- Ethene/ethylene- C2H4 carbon has a double bond and all atoms are on the same plane
What are variations in carbon skeletons?
- Length- carbon skeletons vary in length
- Double bonds- vary in number and location
- Branching
- Rings
What are hydrocarbons?
- Hydrocarbons- organic molecules consisting of only carbon and hydrogen
• Main components in petroleum and fats in the body also have hydrocarbon tails
• Hydrophobic compounds
• Hydrocarbons can undergo reactions that release a large amount of energy
What are isomers?
-Isomers- compounds that have the same numbers of atoms of the the same elements but different structures and hence different properties
How do structural isomers differ and how are they numbered?
• Structural isomers differ in the covalent arrangements of their atoms, may differ in branching or location of double bonds. Increase in number with increase in size.
What are geometric isomers?
• Geometric Isomers- differ in arrangement about a double bond
- Cis isomer- two Xs are on the same side
- Trans isomer- two Xs are on opposite sides
What is an enantiomer?
• Enantiomers are isomers that are mirror images of each other
- The middle carbon is called the asymmetric carbon
- Ibuprofen and Albuterol have enantiomers. Thalidomide cause problems in pregnant women.
What is ATP?
-ATP- Adenosine Tri-phosphate. ATP is an important source of energy for cellular processes. May turn into ADP.
Which functional group often acts as a biological tag?
methyl
How can hydrocarbon chains be changed?
- Chemical groups replace the hydrogen in simple hydrocarbon chains to give organic molecules unique properties.
Radioactive isotopes are useful in scientific research because _____.
they can be used as tracers to follow particular atoms and molecules through metabolic pathways
Which of the following four statements, if any, is true regarding essential elements and living organisms?
Although all forms of life require iron, other elements are required only by certain species.
Sweating has a cooling effect because of water’s high _____.
Heat of vaporization
Why is the increasing amount of carbon dioxide being taken up by the oceans a cause for concern? ()
More carbon dioxide causes an increase in carbonic acid (H2CO3), which leads to a decrease in the concentration of carbonate ion (CO32-).
Using modern equipment, a former graduate student of Stanley Miller recently reanalyzed the sample results of volcano simulation experiments that Miller conducted along with his classic experiment described in the text. This reanalysis _____.
identified additional organic compounds that had not been found by Miller
The first organic molecule to be synthesized from inorganic substances that could be prepared directly from inorganic substances was _____. ()
acetic acid
Which of the following functional groups is associated with a release of energy when removed from the carbon skeleton with water that cells can harvest to perform many functions? ()
phosphate
