Ch. 2 The Chemical Foundation of Life Flashcards
Acid
Molecule that donates hydrogen ions and increases the concentration of hydrogen ions in a solution (thereby decreasing PH).
Base
Molecule that donates hydroxide ions or otherwise binds to excess hydrogen ions and decreases the hydrogen ions’ concentration in a solution (thereby increasing PH).
True or False: acids and based will neutralize eachother.
True
True or False: water is the most abundant molecule in the Earth’s atmosphere. (Nitrogen, followed by Oxygen).
False
Isotopes
One or more forms of an element that have different number of neutrons.
Atom
The smallest unit of matter retains all of the chemical properties of an element.
Element
One of 118 (98 occur naturally) unique substances that cannot break down into smaller substances; each element has unique properties and a specified number of protons.
Matter
Anything that has mass and occupied space.
Neutron
Uncharged particle that resides in an atom’s nucleus; has a mass of one amu.
Molecule
Two or more atoms chemically bonded together.
Nucleus
Core of an atom; contains protons and neutrons.
Octet Rule
Rule that atoms are most stable when they hold eight electrons in their outermost shells.
Orbital
Region surrounding the nucleus; contains electrons.
Organic Molecule
Any molecule containing carbon (except carbon dioxide).
Each carbon molecule can bond with as many as how many other atom(s) or molecule(s)?
Four
Enantiomers
Molecules that share overall structure and bonding patterns, but differ in how the atoms are three dimensionally placed such that they are mirror images of each other. (To be enantiomers, a molecule must have at least three different atoms or groups connected to a central carbon).
True or False: molecules must have a double bond to be cis-trans isomers.
True
Structural Isomer
Molecules that share a chemical formula but differ in the placement of their chemical bonds (ex: CH3CH2COOH and C3H6O2).
Isomer
Molecules that differ from one another even though they share the same chemical formula.
Geometric Isomer
Isomer with similar bonding patterns differing in the placement of atoms alongside a double covalent bond.
True or False: most the atom’s volume - (greater than 99%) - is empty space.
True
Why don’t solid objects just pass through one another if atoms are mostly empty space?
The electrons that surround all atoms are negatively charged and negative charges repel each other.
Atomic Number
Total number of protons in an atom. Used to distinguish one element from another.
Mass Number
Total number of protons and neutrons in an atom.
If xenon has an atomic number of 54 and a mass number of 108, how many neutrons does it have?
54
Potassium has an atomic number of 19. What is its electron configuration?
Shells 1, 2, and 3 are full and shell 4 has one electron.
Electron Configuration
Arrangement of electrons in an atom’s electron shell (ex: 1S^22S^22P^6).
Electron
Negatively charged subatomic particle that resides outside of the nucleus in the electron orbital; lacks functional mass (1/1800 of an atomic mass unit) and has a negative charge of -1 unit.
Electron Orbital
How electrons are spatially distributed surrounding the nucleus; the area where we are most likely to find an electron.
Atomic Mass
Calculated mean of the mass number for an element’s isotopes.
In all electrically neutral atoms…
…the number of electrons is the same as the number of protons.
Bohr Model
Shows the atom as a central nucleus containing protons and neutrons, with electrons in circular orbitals at specific distances from the nucleus. These orbits form electron shells or energy levels (designated by a number and the symbol “n.” Ex: 1n represents the first energy level located closest to the nucleus).
Valence Shell
Outermost shell of an atom. Atoms are more stable energetically when they have eight electrons in their valence shell (octet rule). The electrons in the outermost energy level determine the atom’s energetic stability and it’s tendency to form chemical bonds with other atoms to form molecules.
How electrons fill orbitals…
They first fill the orbitals closest to the nucleus, then they continue to fill orbitals of increasing energy further from the nucleus. Thus, the electron shells of an atom are populated from the inside out, with electrons filling up the low-energy shells closer to the nucleus before they move into the higher-energy shells further out. The shell closest to the nucleus, 1n, can hold two electrons, while the next shell, 2n, can hold eight, and the third shell, 3n, can hold up to eighteen. If there are multiple orbitals of equal energy, they fill with one electron in each energy level before adding a second electron.
Periodic Table organization
Elements are organized and displayed according to their atomic number and are arranged in a series of rows and columns based on shared chemical and physical properties. Scientists base the differences in chemical reactivity between the elements on the number and spatial distribution of an atom’s electrons.
Hydrogen Bond
Weak bond between slightly positively charged hydrogen atoms and slightly negatively charged atoms in other molecules.
Hydrocarbon
(Organic) molecule that consists only of carbon and hydrogen. The backbone of the large molecules of living things.
van der Waals interaction
Very weak interaction between molecules due to temporary charges attracting atoms that are very close together.
Surface tension
Tension at the surface of a body of liquid that prevents the molecules from separating; created by the attractive cohesive forces between the liquid’s molecules.
Adehesion
Attraction between water molecules and other molecules. Important for transporting water from the roots to the leaves in plants.
Cohesion
Intermolecular forces between water molecules caused by the polar nature of water; responsible for surface tension. Important for transporting water from the roots to the leaves in plants.
Capillary action
Occurs because water molecules are attracted charged on the inner surfaces of narrow tubular structures such as glass tubes, drawing the water molecules to the tubes’ sides.
Aliphatic Hydrocarbon
Hydrocarbon consisting of a linear chain of carbon atoms.
Aromatic Hydrocarbon
Hydrocarbon consisting of closed rings of carbon atoms.
Heat of vaporization of water
High amount of energy required for liquid water to turn to water vapor (586 cal). As liquid water heats up, hydrogen bonding makes it difficult to separate the liquid water molecules from each other, which is required for it to enter it’s gaseous phase (steam). As a result, water acts as a heat sink or heat reservoir and requires much more heat to boil. Even when below it’s boiling point (100 degrees Celsius or 212 degrees Fahrenheit), water’s individual molecules acquire enough energy from other water molecules such that some surface water molecules can escape and vaporize (evaporation - allows many living organisms to maintain homeostasis of body temperature).
Specific Heat Capacity
The amount of heat one gram of a substance must absorb or lose to change its temperature by one degree Celsius.
Why is solid ice less dense than liquid water?
Because of the way hydrogen bonds orient as they freeze: the water molecules push further apart compared to liquid water.
Water’s states
gas, liquid, solid
Properties of solids
Has a definite shape, does not flow, virtually impossible to compress, expands if heated but less than liquids and gases.
Particles in solids
Strongly bonded to each other, vibrate a little but not much compared to liquids and gases, vibrate faster when heated.
Properties of liquids
No definite shape, can flow to take the shape of the bottom of a container, very difficult to compress (virtually incompressible).
Particles of liquids
Weakly bonded to each other, break their bonds easily, vibrate and move more than those in a solid, move faster when heated.
Properties of gases
No fixed shape, gases spread (or diffuse) to completely fill a container, gases are easily compressed.
Particles of gases
Are “free,” having no bonds between them, have much more energy than those of a solid or liquid, fly around bouncing off of each other and the walls of their container.
Kinetic Energy
The energy possessed by an object because of its motion, equal to one half the mass of the body times the square of its velocity.
Calorie
Amount of heat required to change the temperature of one gram of water by one degree Celsius.
Anion
Negative ion that is formed by an atom gaining one or more electrons.
Cation
Positive ion that is formed by an atom losing one or more electrons.
Chemical Bond
Interaction between two or more of the same or different atoms that results in forming molecules.
pH Scale
Scale ranging from zero to 14 that is inversely proportional to the hydrogen ions’ concentration in a solution. Anything below 7.0 is acidic while anything above 7.0 is alkaline. (The pH in cells is 6.8 and the pH in blood is 7.4. The pH in stomachs is 1 to 2).
Buffer
Substance that resists a change in pH by absorbing or releasing hydrogen or hydroxide ions.
Functional Group
Group of atoms that provides or imparts a specific function to a carbon skeleton (ex: hydroxyl, phosphate, carbonyl). Usually classified as hydrophobic or hydrophilic depending on their charge or polarity characteristics.
Hydrophobic
Describes uncharged nonpolar molecules that do not interact well with other polar molecules such as water.
Hydrophilic
Describes ions or polar molecules that interact well with other polar molecules such as water.
Nonpolar Covalent Bond
Type of covalent bond that forms between atoms when electrons are shared equally between them.
Polar Covalent Bond
Type of covalent bond that forms as a result of unequal electron sharing, resulting in creating slightly positive and negative charged molecule regions.
Covalent Bond
Type of strong bond formed between two atoms of the same or different elements; forms when electrons are shared between atoms.
Balanced Chemical Reaction
Statement of a chemical reaction with the number of each type of atom equalized for both the products and reactants.
Compound
Substance composed of molecules consisting of atoms of at least two different elements.
Electron Transfer
Movement of electrons from one element to another; important in creating ionic bonds.
Ionic Bond
Chemical bond that form’s between ions with opposite charges (cations and anions).