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EK Chem 1
atoms, molecules, and quantum mechanics
| Question | Answer |
|---|---|
| atoms | tiny particles that make up mass, composed of nucleus surrounded by 1 or more electrons; size is mostly from the space between the electrons and nucleus |
| nucleus of atom | contains protons and neutrons (collectively nucleons) which are held together by strain nuclear force |
| proton | positive charge, same mass as neutron |
| neutron | neutral charge, same mass as proton |
| electron | negative charge, mass much smaller than that of proton or neutron (1/1800) |
| element | building blocks of all compounds and cannot be decomposed into simpler smaller substances by any chemical means |
| mass number | denoted as A (top left corner of the elemental symbol), proton + neutrons |
| atomic number | denoted as Z (bottom left corner of the elemental symbol), number of protons |
| isotope | two or more atoms of the same element that contain different number of neutrons |
| amu | atomic mass unit, aka dalton, defined by carbon-12 (one atom of carbon 12 has an atomic weight of 12 amu) |
| atomic weight | aka molar mass, given in amu's |
| mole | aka Avogadro's number, 6.022 x 10^23, the number of carbon atoms in 12 grams of carbon 12--> = grams/atomic or molecular weight |
| periodic table | lists elements from left to right in order of their atomic numbers, divides elements into nonmetals on right side, metals on the left side, and metalloids along the diagonal separating the nonmetals and metals |
| period of the periodic table | horizontal rows of periodic table |
| groups of periodic table | aka families, vertical rows of periodic table |
| metals | large atoms, tend to lose e's to form +ions or form + oxidation state, described as a sea of e's which move easily making them ductile (easily stretched), malleable (easily hammered into thin strips), thermal and electrical conductivity, and have a luster |
| nonmetals | diverse appearances and chemical behaviors, lower melting points than metals, form negative ions |
| metalloids | some characteristics that resemble metals and some that resemble non metals |
| transition metals | section B groups |
| hydrogen | unique, does not fall conform to any family, nonmetal, under most conditions is a colorless, odorless, diatomic gas |
| alkali metals | (Group 1A) soft metallic solids with low densities and low melting points, form 1+ cations easily, highly reactive, only exist in compounds in nature |
| alkaline earth metals | (Group 2A) harder, more dense, and melt at higher mp's than alkalis, form 2+ cations easily, less reactive than alkalis |
| 4A elements | can form 4 covalent bonds with nonmetals but only carbon can form 2 additional bonds with Lewis bases, only carbon forms strong pi bonds |
| 5A elements | can form 3 covalent bonds, all except nitrogen can use d orbitals to make 5 covalent bonds, only N and P can make pi bonds |
| 6A elements | aka chalcogens, most important of the group are O and S |
| 7A elements | aka halogens, highly reactive, fluorine, chlorine, bromine, and iodine |
| noble gas | nonreactive, aka inert gases, normally found in nature as isolated atoms, gases at room temperature |
| diatomic molecules | hydrogen, oxygen, nitrogen, and halogens |
| small atoms.. | less room to stabilize charge by spreading it out so it will bind strongly to water (greater heats of hydration), no d orbitals so no more than 4 bonds but make strong pi bonds due to overlap of p orbitals |
| large atoms.. | unable to make strong pi bonds bc not enough overlap but can have d orbitals allowing for more than 4 bonds |
| cation | positive ion, significantly smaller than their neutral atom counterparts |
| anion | negative ion, larger than their neutral atom counterparts |
| transition metals as ions | will lose e's from their s subshell before their d subshell (bc atoms typically lose e's from the highest energy shell first) |
| effective nuclear charge (Zeff) | amount of charge felt by the second e', it won't feel the entire nuclear charge b/c the first e' shields it, = the nuclear charge (Z) minus the average # of e's between nucleus and e' in question |
| Zeff trend | increases across (L-->R) and down the periodic table; the shielding increases with the addition of another subshell but decreases when adding to the same subshell |
| periodic trends | predictions about elements based on their position in the periodic table, includes trends in atomic radius, ionization energy, electronegativity, and electron affinity |
| atomic radius | increases going down the table and from right to left of the table, when Zeff decreases each e' is pulled in stronger creating smaller atomic radius |
| ionization energy | energy necessary to detach an electron from a nucleus, generally increases from left to right and from bottom to top |
| first ionization energy | energy necessary to detach an e' from a neutral atom |
| second ionization energy | energy for removal of second e' from the same atom |
| electronegativitiy | tendency of an atom to attract an e' in bond that shares with another atom, tends to increase from L to R and up the periodic table |
| electron affinity | willingness of an atom to accept an additional e', energy released when an e' is added to a gaseous atom, increases from L to R and up the table |
| metallic character | tends to increase from R to L and down the table |
| covalent bond | two e's shared by two nuclei where the repulsive and attractive forces of the + and - charged particles are balanced to create this bond |
| bond length | defined as the point where their energy level is lowest |
| bond dissociation energy | energy necessary to achieve a complete separation |
| compound | substance made of two or more elements in a definite proportions |
| empirical formula | ratio of whole numbers that represent the relative number of 1 element to another |
| molecules | distinct and separate units repeated formed from groups of atoms |
| molecular formula | exact number of elemental atoms in each molecule |
| how to find % composition by mass | (1) multiply an atom's atomic weight by the # of atoms it contributes to the empirical formula (2) divide the result by the weight of all the atoms in the empirical formula (3)multiple fraction by 100 |
| how to find empirical formula | (1) assume you have 100 g sample and percentage = # grams (2) divide grams by atomic weight to get moles (3) divide by greatest common factor to give empirical formula |
| ionic compounds | named after cation and anion (cation name goes in front of anion name) |
| monatomic ions and simply polyatomic anions suffix | -ide |
| polyatomic anions with oxygens | -ite for -ate depending on number of oxygens with hypo- and per- suffixes for the fewest and most oxygens respectively |
| acids | names based on their anions. if anion ends in 'die then acid name starts with hydro and end with -ic |
| binary molecular compounds | compounds with 2 elements, name begins with the name of the element that is furthest to the left and lowest in the periodic table, and the 2nd element is given suffix -ide (eg |
| physical rxn | when a compound undergoes a rxn and maintains its molecular structure (melting, evaporation, dissolution, and rotation of polarized light) |
| chemical rxn | when a compound undergoes a rxn and changes its molecular structure to form a new compound (ex |
| theoretical yield | amount of product produced when a rxn runs to completion |
| limiting reagent | reactant that would be completely used up if the reaction were run to completion |
| percent yield | actual yield / theoretical yield * 100 |
| combination rxn type | A + B --> C |
| decomposition rxn type | C--> A + B |
| single displacement rxn | A + BC --> B + AC |
| double displacement rxn | AB + CD --> AD + CB aka metathesis reaction |
| crystal solid | sharp melting point and characteristic shape, well ordered structure with repeating units, can be ionic, network covalent, metallic, or molecular |
| amorphous solid | no characteristic shape, melts over temperature range |
| principal quantum number | n, designates the shell level |
| azimuthal quantum number | l, designates the subshell (s, p, d, and f), = n-1, each has a peculiar shape |
| magnetic quantum number | m, designates the precise orbital of a subshell, ranges from -l to +l |
| electron spin quantum number | ms, either -1/2 or +1/2 |
| Pauli exclusion principle | no two e's in the same atom can have the same 4 quantum numbers |
| number of total orbitals w/in a shell = | n^2 |
| Heisenberg uncertainty principle | the more than is known about the momentum of a particle, the less we can know about the position |
| Aufbau principle | with each new proton added to create a new element, a new e' is added as well |
| electron configuration | a way to show the shells and subshells from lowest to highest energy level with a subscript to show the # of e's in each subshell |
| electron configuration relative energy table | 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 1s-2s-2p-3s-3p-4s-3d-4p-5s -etc |
| Hund's rule | e's will not fill any orbital in the same subshell until all orbitals in that subshel contain at least 1 e' and the unpaired e's will have parallel spin, e's also prefer to have its own orbital when available |
| Planck's quantum theory | electromagnetic energy is quantizied-- if we transfer energy from one point to another via electromagnetic wave, and we wish to increase that energy w/o changing f, then we can only change it in discrete increments (E = hf) |
| when an e' fall from higher energy rung to lower energy rung… | energy is released as a photon |
| if photon collides with an e'… | it can only bump the e' to another energy level rung and not between, if not enough energy, photon will be reflected away |
| photoelectric effect | e's from higher to lower release photons and e's need to absorb photon to go from lower to higher energy |
Created by:
miniangel918
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