pg 29-57 Flashcards
4 elements common in all living organisms
O, C, H, N
element mass=
proteins plus neutrons
different forms of an element that have the same number of protons but a different number of neutrons.
isotopes
Some isotopes may emit neutrons, protons, and electrons, and attain a more stable atomic configuration (lower level of potential energy)
radioisotopes
chemical reactivity
the ability to combine and to chemically bond with each other.
two or more atoms chemically bonded together.
molecules
The Bohr model
-shows the atom as a central nucleus containing protons and neutrons, with the electrons in circular orbitals at specific distances from the nucleus
with the exception of the innermost shell, that atoms are more stable energetically when they have eight electrons in their valence shell
octet rule
another word for noble gases
inert
As a result of losing a negatively charged electron, they become positively charged ___
ions
since not all elements have enough electrons to fill their outermost shells, atoms form _____
chemical bonds
occur when two or more atoms bond together to form molecules or when bonded atoms break apart
Chemical reactions
Reversible reactions are those that can go in either direction. In reversible reactions, reactants turn into products, but when the product’s concentration goes beyond a certain threshold (characteristic of the particular reaction), some of these products convert back into reactants. At this point, product and reactant designations reverse. This back and forth continues until a certain relative balance between reactants and products occurs—a state called _____. A chemical equation with a double headed arrow pointing towards both the reactants and products often denote these reversible reaction situations.
equilibrium
- positive ions that form by losing electrons.
- Negative ions form by gaining electrons, which we call ____
- cations
- anions
We designate anions by their ____ ____ and change the ending to “___”,
- elemental name
- -ide
- thus the anion of chlorine is chloride, and the anion of sulfur is sulfide.
electron transfer
Scientists refer to this movement of electrons from one element to another
form between ions with opposite charges
ionic bonds
examples of electrolytes
sodium, potassium, and calcium
These bonds are stronger and much more common than ionic bonds in the molecules of living organisms
covalent bonds
two types of covalent bonds
polar and nonpolar
form between two atoms of the same element or between different elements that share electrons equally
nonpolar covalent bonds
Two weak bonds that occur frequently are ___ and ____. Without these two types of bonds, life as we know it would not exist.
-hydrogen bonds and van der Waals interactions
___ bonds provide many of the critical, life-sustaining properties of water and also stabilize the structures of proteins and DNA, the building block of cells.
Hydrogen
When polar covalent bonds containing hydrogen form, the hydrogen in that bond has a slightly ____ charge because hydrogen’s electron is…
- positive
- pulled more strongly toward the other element and away from the hydrogen
Hydrogen Bond
- common and occurs regularly between water molecules
- Individual hydrogen bonds are weak and easily broken; however, they occur in very large numbers in water and in organic polymers, creating a major force in combination
- Hydrogen bonds are also responsible for zipping together the DNA double helix
van der Waals interactions
- are weak attractions or interactions between molecules.
- can occur between any two or more molecules and are dependent on slight fluctuations of the electron densities, which are not always symmetrical around an atom
- For these attractions to happen, the molecules need to be very close to one another.
- These bonds—along with ionic, covalent, and hydrogen bonds—contribute to the proteins’ three-dimensional structure in our cells that is necessary for their proper function
As a result of water’s polarity, each water molecule attracts other water molecules because of the ____ charges between water molecules, forming hydrogen bonds. Water also attracts or is attracted to other
- opposite
- polar molecules and ions.
What makes ice less dense than liquid water.
Hydrogen bonding
What has the highest specific heat capacity of any liquids
water
the amount of heat one gram of a substance must absorb or lose to change its temperature by one degree Celsius
Specific Heat
We define specific heat as the amount of heat one gram of a substance must absorb or lose to change its temperature by one degree Celsius. For water, this amount is ____. It therefore takes water a long time to ____ and a long time to ___.
one calorie
- heat
- cool
the amount of energy required to change one gram of a liquid substance to a gas
heat of vaporization
a substance capable of dissolving other polar molecules and ionic compounds
solvent
Therefore, we refer to water as a solvent, a substance capable of dissolving other polar molecules and ionic compounds. The charges associated with these molecules will form hydrogen bonds with water, surrounding the particle with water molecules. We refer to this as a _______, or a hydration shell and serves to keep the particles seperated or dispersed in water
sphere of hydration
When we add ionic compounds to water, the individual ions react with the water molecules’ polar regions and their ionic bonds are disrupted in the process of ___. _____ occurs when atoms or groups of atoms break off from molecules and form ions
dissociation
water molecules are attracted to each other (because of hydrogen bonding), keeping the molecules together at the liquid-gas (water-air) interface, although there is no more room in the glass.
cohesion
Cohesion allows for _____, the capacity of a substance to withstand rupturing when placed under tension or stress.
surface tension
attraction between water molecules and other molecules.
adhesion
capillary action
- movement of water within the spaces of a porous material due to the forces of adhesion, cohesion and surface tension. It is the ability of a liquid to flow in narrow spaces without the assistance of, and sometimes in opposition to, external forces like gravity
- occurs when the adhesion to the walls is stronger than the cohesive forces between the liquid molecules
litmus
pH paper
One mole represents the ____ weight of a substance, expressed in grams, which equals the amount of the substance containing as many units as there are atoms in 12 grams of 12C. Mathematically, one mole is equal to ______ particles of the substance.
- atomic
- 6.02 × 10^23
a substance that increases hydrogen ions’ (H+) concentration in a solution, usually by having one of its hydrogen atoms dissociate
acid
provides either hydroxide ions (OH–) or other negatively charged ions that combine with hydrogen ions, reducing their concentration in the solution and thereby raising the pH
base
T he stronger the acid, the more readily it donates
H+
pH scale range
- 0-14
- <7 = acidic
- > 7=alkaline
readily absorb excess H+ or OH–, keeping the body’s pH carefully maintained in the narrow range required for survival
buffers
subset of organic molecules (any carbon-containing liquid, solid, or gas) that are especially important for life.
macromolecules
The fundamental component for all of these macromolecules is
carbon
are organic molecules consisting entirely of carbon and hydrogen, such as methane (CH4) described above
hydrocarbons
Successive bonds between carbon atoms form
hydrocarbon chains
consist of linear chains of carbon atoms
aliphatic hydrocarbons
-consists of closed rings of carbon atoms with alternating single and double bonds
aromatic hydrocarbons
We find ring structures in ____ hydrocarbons, sometimes with the presence of double bonds, which we can see by comparing cyclohexane’s structure to benzene
aliphatic
We call molecules that share the same chemical formula but differ in the placement (structure) of their atoms and/or chemical bonds
isomers
differ in the placement of their covalent bonds: both molecules have four carbons and ten hydrogens (C4H10), but the different atom arrangement within the molecules leads to differences in their chemical properties
Structural isomers
have similar placements of their covalent bonds but differ in how these bonds are made to the surrounding atoms, especially in carbon-to-carbon double bonds
geometric isomers
When the carbons are bound on the same side of the double bond, this is the ___ configuration. If they are on opposite sides of the double bond, it is a ___ configuration. In the ___ configuration, the carbons form a more or less linear structure; whereas, the carbons in the ___ configuration make a bend (change in direction) of the carbon backbone.
- cis
- trans
- trans
- cis
Which of the following statements is false?
a. Molecules with the formulas CH3CH2COOH and C3H6O2 could be structural isomers.
b. Molecules must have a double bond to be cis-trans isomers.
c. To be enantiomers, a molecule must have at least three different atoms or groups connected to a central carbon.
d. To be enantiomers, a molecule must have at least four different atoms or groups connected to a central carbon.
In triglycerides (fats and oils), long carbon chains known as fatty acids may contain double bonds, which can be in either the cis or trans configuration, as Figure 2.25 illustrates. Fats with at least one double bond between carbon atoms are ____ fats.
-unsaturated
When some of these bonds are in the cis configuration, the resulting bend in the chain’s carbon backbone means that triglyceride molecules cannot pack tightly, so they remain liquid (oil) at room temperature. Alternatively, triglycerides with trans double bonds (popularly called ______), have relatively linear fatty acids that are able to pack tightly together at room temperature and form solid fats.
-trans fats
Enantiomers
molecules that share the same chemical structure and chemical bonds but differ in the three-dimensional placement of atoms so that they are non-superimposable mirror images
molecules that share the same chemical structure and chemical bonds but differ in the three-dimensional placement of atoms so that they are non-superimposable mirror images
functional groups
Molecules with other elements in their carbon backbone are
substituted hydrocarbons
Which of the following statements is false?
b. Molecules must have a double bond to be cis-trans isomers. c. To be enantiomers, a molecule must have at least three different atoms or groups connected to a central carbon. d. To be enantiomers, a molecule must have at least four different atoms or groups connected to a central carbon.
b. Molecules must have a double bond to be cis-trans isomers.
c. To be enantiomers, a molecule must have at least three different atoms or groups connected to a central carbon.
d. To be enantiomers, a molecule must have at least four different atoms or groups connected to a central carbon.
When acids are added to a solution, the pH should
a. decrease b. increase c. stay the same d. cannot tell without testing
Which of the following statements is not true? a. Water is polar. b. Water stabilizes temperature. c. Water is essential for life. d. Water is the most abundant molecule in the Earth’s atmosphere.
Which of the following statements is true? a. Acids and bases cannot mix together. b. Acids and bases will neutralize each other. c. Acids, but not bases, can change the pH of a solution. d. Acids donate hydroxide ions (OH–); bases donate hydrogen ions (H+).
Which of the following is not a functional group that can bond with carbon? a. sodium b. hydroxyl c. phosphate d. carbonyl
Which of the following is not a functional group that can bond with carbon? a. sodium b. hydroxyl c. phosphate d. carbonyl
Why are hydrogen bonds and van der Waals interactions necessary for cells?
Discuss how buffers help prevent drastic swings in pH.
Why can some insects walk on water?
What property of carbon makes it essential for organic life?
Compare and contrast saturated and unsaturated triglycerides.
