gen chem Flashcards
(105 cards)
1
Q
Atomic number
A
number of protons in the neuclus of an atom
2
Q
Atomic mass
A
Atomic mass is the average mass of the protons, neutrons, and electrons in an atom.
3
Q
Elements
A
An element is a pure substance that is made from a single type of atom.
4
Q
compounds
A
a substance made up of two or more different chemical elements combined in a fixed ratio
5
Q
Isotopes
A
Atoms with the same number of protons but different numbers of neutrons
6
Q
Radioactivity
A
the release of energy from the decay of the nuclei of certain kinds of atoms and isotopes.
7
Q
Avogadro’s number
A
the number of particles in 1 mole (or mol) of a substance.
6.022×10^23 mol−1
8
Q
Building up principle
A
in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy level before occupying higher-energy levels
9
Q
Quantum numbers
A
The set of numbers used to describe the position and energy of the electron in an atom
10
Q
Atomic orbitals
A
An orbital is a three dimensional description of the most likely location of an electron around an atom.
11
Q
Pauli exclusion principle
A
in an atom or molecule, no two electrons can have the same four electronic quantum numbers.
12
Q
Hund’s rule
A
every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.
13
Q
Covalent bond
A
the force of attraction that holds together two atoms that share a pair of valence electrons.
14
Q
Bonding energies
A
the amount of energy required to break apart a mole of molecules into its component atoms.
15
Q
Resonance
A
describes the delocalization of electrons within molecules
16
Q
delocalized bonding
A
a bond that appears in some resonance forms, but not others.
17
Q
Polar covalent bond
A
a covalent bond in which the atoms have an unequal attraction for electrons, and so the sharing is unequal.
Slightly positive side, slightly negative charge ex H2O
18
Q
Dipole moment
A
a measure of the system’s overall polarity. a measurement of the separation of two opposite electrical charges.
19
Q
Ionic bond
A
formed between two or more atoms by the transfer of one or more electrons between atoms
20
Q
Intermolecular forces
A
he attractive and repulsive forces that arise between the molecules of a substance.
21
Q
Hydrogen bonding
A
a weak bond between two molecules resulting from an electrostatic attraction between a proton in one molecule and an electronegative atom in the other.
22
Q
Van der Waals forces
A
relatively weak electric forces that attract neutral molecules to one another in gases, in liquefied and solidified gases, and in almost all organic liquids and solids.
23
Q
dipole-dipole
A
attractive forces between the positive end of one polar molecule and the negative end of another polar molecule.
24
Q
London forces
A
a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles.
25
Ideal gas law
ideal gas law, relation between the pressure P, volume V, and temperature T of a gas in the limit of low pressures and high temperatures, such that the molecules of the gas move almost independently of each other.
PV=nRT
26
Sublimation
Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the liquid state.
27
lyophilization
a drying technique by which a product is solifidied by freezing and the solvent that contains it (usually water) is evaporated by sublimation
28
Microheterogeneous systems
A closed system containing at least two phases is called a heterogeneous system. Reactions (changes) between or among phases are driven by energy manifested in temperature of chemical potentials. ex ice, water and steam
29
colloidal state and size
a mixture that has particles ranging between 1 and 1000 nanometers in diameter, yet are still able to remain evenly distributed throughout the solution.
30
Tyndall effect
When light is passed through a colloidal solution, it is observed that the colloidal particles do not permit the light to pass through it completely
31
Types of colloids
The types of colloids includes sol, emulsion, foam, and aerosol.
Sol is a colloidal suspension with solid particles in a liquid.
Emulsion is between two liquids.
Foam is formed when many gas particles are trapped in a liquid or solid.
Aerosol contains small particles of liquid or solid dispersed in a gas.
32
hydrophobic
a property of molecules that do not mix with water
33
hydrophilic
molecule is one that is able to interact with water
34
dispersed
a system in which distributed particles of one material are dispersed in a continuous phase of another material.
35
macromolecular
large polymer molecules made up of several smaller molecules bonded together by covalent bonds.
36
association colloids
Associated colloids are those colloids which behave as normal strong electrolytes at low concentrations but exhibit colloidal properties at higher concentrations due to the formation of aggregated particles.
37
Homogeneous systems
one whose properties are either the same throughout the system, or vary continuously from point to point with no discontinuities.
38
Saturated solutions
A solution with solute that dissolves until it is unable to dissolve anymore, leaving the undissolved substances at the bottom
39
unsaturated solutions
a solution that contains less than the maximum amount of solute that is capable of being dissolved.
40
Solubility
is the ability of a substance, the solute, to form a solution with another substance, the solvent.
41
Osmosis
the passage of water and small molecules across a semipermeable membrane with a net flow from a less concentrated solution to a more concentrated solution.
42
Chemical equilibrium
a state of balance in a reaction where the forward and reverse reaction speed is equal and the concentrations of the products and reactants remain unchanged.
43
equilibrium constant
expresses the relationship between products and reactants of a reaction at equilibrium with respect to a specific unit.
44
law of mass action
the rate of a reaction is proportional to the product of the concentrations of each reactant.
45
Le Chatelier’s principle
A change in one of the variables that describe a system at equilibrium produces a shift in the position of the equilibrium that counteracts the effect of this change.
46
precipitation
is the formation of a solid in a solution during a chemical reaction.
47
gas formation
a chemical reaction produces a gas as one of its products.
48
neutralization
when an acid and a base react to form water and a salt and involves the combination of H+ ions and OH- ions to generate water.
49
Solubility equilibrium
a type of dynamic equilibrium that exists when a chemical compound in the solid state is in chemical equilibrium with a solution of that compound.
Ksp=[A]^a[B]^b
50
solubility product constant
Ksp, is the equilibrium constant for a solid substance dissolving in an aqueous solution. It represents the level at which a solute dissolves in solution. The more soluble a substance is, the higher the Ksp value it has.
51
Electrolytes
a substance that dissociates in water into charged particles called ions.
52
degree of dissociation
the percentage of substance that has dissociated.
53
Bronsted-Lowry
A Brønsted-Lowry acid is any species that can donate a proton, , and a base is any species that can accept a proton.
54
Amphoteric species.
molecules or ions that can react as an acid as well as a base
55
Lewis concept of acids and bases
a Lewis acid is an electron-pair acceptor. A Lewis base is any substance, such as the OH- ion, that can donate a pair of nonbonding electrons.
56
Self-ionization of water
The reaction in which a water molecule donates one of its protons to a neighbouring water molecule
57
Ion product of water
The ion product of water, Kw = [H3O+] [OH−], has the value 1.0 × 10^−14
58
dissociation constants
(KD) is a specific type of equilibrium constant that measures the propensity of a larger object to separate (dissociate) reversibly into smaller components
59
hydrolysis
a chemical reaction in which a molecule of water breaks one or more chemical bonds
60
Acid-base titration
used to find the amount of a known acidic or basic substance through acid base reactions
61
titration curves
a graphical representation of the pH of a solution during a titration. In a strong acid-strong base titration, the equivalence point is reached when the moles of acid and base are equal and the pH is 7
62
Common-ion effect
an effect that suppresses the ionization of an electrolyte when another electrolyte (which contains an ion which is also present in the first electrolyte, i.e. a common ion) is added
63
Buffers
a solution that can resist pH change upon the addition of an acidic or basic components
64
Henderson-Hasselbalch equation
provides a relationship between the pH of acids (in aqueous solutions) and their pKa (acid dissociation constant).
pH= pKa+log [A-]/[HA]
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Types of buffers.
acidic buffer and basic buffer: A solution with weak acid and its salts containing strong bases is called an acidic buffer solution. E.g., A solution with CH3COOH, which is weak acid and CH3COONa, which is its salt is an acidic buffer solution
66
Buffer capacity
the moles of an acid or base necessary to change the pH of a solution by 1, divided by the pH change and the volume of buffer in liters
67
Thermodynamics
the study of the relations between heat, work, temperature, and energy.
68
State functions
a property whose value does not depend on the path taken to reach that specific value
69
Exothermic reactions
if heat is released by the system into the surroundings
70
endothermic reactions
any chemical reaction that absorbs heat from its environment
71
Internal energy
all the energy within a given system, including the kinetic energy of molecules and the energy stored in all of the chemical bonds between molecules.
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The first law of thermodynamics
energy cannot be created or destroyed; it can only be converted from one form to another
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The second laws of thermodynamics
the state of entropy of the entire universe, as an isolated system, will always increase over time
74
The heat of reaction and enthalpy
the change in the enthalpy of a chemical reaction that occurs at a constant pressure. It is a thermodynamic unit of measurement useful for calculating the amount of energy per mole either released or produced in a reaction.
75
Hess’s law
regardless of the multiple stages or steps of a reaction, the total enthalpy change for the reaction is the sum of all changes.
76
Entropy
describes the randomness and disorder of molecules based on the number of different arrangements available to them in a given system or reaction.
order to disorder takes no energy but it is spontaneous
77
third laws of thermodynamics
the entropy of a system approaches a constant value as the temperature approaches absolute zero
78
Entropy changes for a reaction
the standard entropy change is the sum of the standard molar entropies of the products minus the sum of the standard molar entropies of the reactants.
79
Spontaneous reactions
a reaction that favors the formation of products at the conditions under which the reaction is occurring there is a decrease in the energy of the system as energy is released to the surroundings as heat
80
Gibbs Free energy
combines enthalpy and entropy into a single value. The change in free energy, ΔG, is equal to the sum of the enthalpy plus the product of the temperature and entropy of the system.
81
Electrodes
a metal whose surface serves as the location where oxidation-reduction equilibrium is established between the metal and what is in the solution
82
voltaic cells
use a thermodynamically favored redox reaction to generate an electric current
83
standard potential
the ability of a species to gain or lose electrons, i.e., its reduction or oxidation potential.
84
standard potential
a measure of the reducing power of any element or compound
85
Electromotive force
the electric potential produced by either an electrochemical cell or by changing the magnetic field.
86
Nernst equation
The Nernst Equation enables the determination of cell potential under non-standard conditions.
E=E˚-(RT/nF)*ln(Q)
E= reduction potential
E˚=standard potential
R=gas constant
T=temp
n= moles of electrons
F=faraday constant
Q=reaction quotient
87
Redox reactions
are reactions that involve the transfer of electrons from one species to another
88
Reaction kinetics
study of reaction rate
89
Elementary reactions
chemical reaction in which one or more chemical species react directly to form products in a single reaction step and with a single transition state
90
molecularity of a reaction
the number of molecules that come together to react in an elementary (single-step) reaction
91
Reaction rate
the speed at which a chemical reaction proceeds
92
Rate law
that provides a relationship between the rate of the reaction and the concentrations of the reactants participating in it.
93
rate constant
the proportionality constant in the equation that expresses the relationship between the rate of a chemical reaction and the concentrations of the reacting substances
rate=K[A]^a[B]^b
94
Reaction order
first order= concentration x2 rate x2
Second order= concentration x2 rate x4
zero order= concentration x2 rate x1
95
Activation energy
the minimum energy required to cause a process (such as a chemical reaction) to occur.
96
Activated complex
the state of a molecule when the reaction is at the point of activation energy.
97
complex chemical reactions
takes place when the reactants are converted into products in multiple steps or more than one step
98
Catalysts
a substance that speeds up a chemical reaction, or lowers the temperature or pressure needed to start one, without itself being consumed during the reaction.
99
peroxides
any of a class of chemical compounds in which two oxygen atoms are linked together by a single covalent bond
99
Enzymes
proteins that act upon substrate molecules and decrease the activation energy necessary for a chemical reaction to occur by stabilizing the transition state.
99
oxides
a chemical compound containing at least one oxygen atom and one other element in its chemical formula. Oxide itself is the dianion (anion bearing a net charge of –2) of oxygen, an O2– ion with oxygen in the oxidation state of −2.
100
superoxides
a compound that contains the superoxide ion, which has the chemical formula O−2
101
Complex compounds
a class of substances with a chemical structure where the central atom is a metal and it is surrounded by non-metal atoms or a group of atoms
102
Coordination number
the number of atoms, ions, or molecules that a central atom or ion carries in a complex or coordination compound or in a crystal as its closest neighbours.
103
Chelate complexes
any of a class of coordination or complex compounds consisting of a central metal atom attached to a large molecule, called a ligand, in a cyclic or ring structure.
ex hemoglobin
