Chemistry Final Semester 1

the study of matter and how it reacts with energy on a molecular level
the amount of disorder between molecules in a substance
anything that takes up space
it's a unit of measure used to determine the number of atoms in a molecule, equal to 6.022 x 10^23; multiply mole by atomic mass of element to find the number of moles in an atom; moles = grams/molar mass; # of grams = molar mass x moles
an observed fact
basic unit of an element
atom of an element with different massed neutrons
atomic number
used to identify an element; number of protons in element; a whole number
emission spectrum
light given off by excited atoms
dual nature of light
number of vibrations produced per second in Hertz
non reactive
atom that either gains or loses 1 or more electrons
valence electrons
electrons on outer orbital of atom; highest energy level
lower level of entropy where molecules vibrate around a fixed point
higher level of entropy than a solid where molecules flow freely
higher level of entropy that a liquid where molecules flow freely
higher level of entropy than a gas where molecules flow freely and conduct electricity
Bose-Einstein Condensate
higher level of entropy than a plasma where molecules begin to combine into a single massive molecule
physical properties
observed without changing the substance's chemical properties; melting point, odor...
chemical properties
observed when a substance reacts with another substance chemically: toxicity, flammability, reactivity...
atom vs molecule
An atom exists within a molecule, and is an element. A molecule can have one or more types of atoms inside it, and can be an element or a compound.
element vs compound
an element can not be broken down into simpler substances, while a compound can
endothermic reaction
The heat comes from from the molecules changing identity, from energy. The energy was transferred according to the law of conservation of energy.
importance of conservation of matter
Atoms cannot be created nor destroyed, only transferred; a scientist could determine what original substances were combined with to make new ones, and from there a formula could be developed.
noble gasses
they do not react to extreme heat or energy because they've already reached the octet, so they are considered lazy; 2s2p6
sources of periodic table's symbols
The universal language chosen to represent the elements was latin; in latin the symbol of gold Au makes sense, it's Aurorium. Once new elements came along where the letter was already taken they were given a second letter to differentiate themselves.
three fundamental measurements of chemistry
mass- kilo
temperature- kelvin
mole- amount of matter
base metric measurements
They are the starting points where all other units of measure are based upon, their definition.
answering questions with science
The scientific method does not use guesses, rather a tight set of rules. A hypothesis is an educated statement based on a previous researched that cannot be changed to match results after an experiment.
dimensional analysis cannot be used to convert units
If there's no equality you cannot make a conversion. You must change the unit.
accuracy vs precision
Accuracy is based on a known answer, while precision is based on the tool you use to measure with. it's assumed that the more precise of a tool used the more accurate your answer will be.
theory vs hypothesis
theories have been tested so many times that they've been proven correct; hypotheses can e either true or false; every theory started with a hypothesis
the metric system over time
It's become more and more accurate; the meter was first based on a distance divided between the north and south poles, and has since been changed to a certain distance that light travels. The more accurate an answer the more beneficial research would be and people could agree on answers.
derived unit
uses to who base measurements. this could be density (mass/volume) like g/m3 or finding the amount of substance in a given volume (moles/m3).
importance of rounding to significance
It will let me and my readers know the precision of my instrument, and the numbers i got with it. the more precise the less confusion there will be in comparing with other answers.
determining significant values
count numbers over 0 after the decimal; don't count 0's in numbers before/after decimal unless in between numbers <0;
must be rounded to sigfigs least number, and scinot between 1 and 10
add units to answers or they will not be counted; cm x cm = cm^2; cm/cm = no unit
Dalton's important parts to atomic theory
1. during a chemical reaction elements cannot be created nor destroyed, only rearranged, combined, or subdivided
2. compounds with the same elements exist in whole number ratios; when they behave different they have different proportions- a fixed ratio.
four common parts of the atom
1. proton- positive charge, with a weight of 1836/1837th of a hydrogen atom; found in nucleus; most important part of atom because it identifies the atom
2. electron-negative charge with a weight of 1/1837th of a hydrogen atom. Found around nucleus.
3. nucleus- positive mass located in the center of the atom- very tiny.
4. neutron- located in nucleus with no charge; mass of 1837/1837th of hydrogen atom.
four forces of the universe
gravity-not affective at atomic level; what gives an object mass
electromagnetic force- positive and negative charges attract; keeps matter from existing in two places at once
strong nuclear force- bonds protons together in a tight place
weak nuclear force- stronger force overcomes strong force and makes atoms separate; radioactive element
avogrado's number
6.022 x 10^23; number of atoms in a given element; with it you can find how many atoms are in a certain number of grams; you use moles for mathematical conversions at a molecular level.
rutherford's experiment
he had a screen surrounding a malleable gold foil at which he shot protons. he found 99% of the protons went straight through, and the rest either shot straight back on went in another direction. from this he found there must be a nucleus, protons are positive, electrons surround the nucleus, and neutrons exist in the nucleus with a neutral charge.
purpose of neutron
holds the atom's nucleus together; nucleus would tear apart without them
radioactive isotope substitution
They can be substituted for non radioactive isotopes with not change in results because it's a physical property. Chemically they're exactly the same.
most common isotope mass
is the element's atomic mass rounded to the nearest whole number. The process works because it's the most commonly occurring, unique to all other elements' isotopes.
quantum values
N- principle quantum number and main energy level; whole numbers 1-7
L- orbital quantum number determines which suborbital (N-1) to 0
M- magnetic quantum number tells which orbital the electron is in; -l to 0 to l
S- spin quantum number is the spin level and says you can only have two electrons in any main energy level; up or down
quantum values, electron configuration, and orbital notation
ex. 1 0 0 up/down; 2s2p6 (inconsistency 3d1 and 4s2 switched); up down combination (remember hund's rule)
3 principles of quantum mechanics model
aufbau- an electron goes into the lowest energy level first and works its way up
pauli's exclusionary- each electron has a unique set of four numbers: N, L, M, and S
hund's- you must first list all the possible electrons in a main energy level before giving their pairs
atoms releasing energy
an atom absorbs energy and moves from one energy level to the next.
it knows it not in the right place and so release energy, giving off a photon of light.
by back tracing the energy of an atom you can tell where it was before it got excited and emitted light.
why an atom gives off different light in its emission spectrum
during each energy drop it gives you different colors, and enters different energy levels
how it's possible for two electrons to occupy the same space orbital
they must be waves out of phase, overlapping at nullpoint
frequency and wavelength
multiplied together determine the speed of light
frequency of a beam of light -> energy it can carry
the frequency determines the color of a beam; the higher the energy the higher the frequency
how many of the same orbitals an energy level can have?
how many ways you can orientate the shape without overlapping the orbitals
importance of element's number and location of electrons
can determine how the atom acts and its location
four periodic table family names
alkali metals- group 1
alkaline earth metals- group 2
transitional metals- groups 3-12
noble gasses- group 18
atomic size
metals lose electrons; the larger atom, the easier it is to lose, so it's more active
was the first to organize the elements by atomic number, and discovered the periodic law; he arranged elements by atomic weight and properties; there were gaps where atoms were supposed to match but weren't there, so he determined not all the elements were known
nonmetal activity
nonmetals gain electrons; small atoms have greater aptitude for electrons thus more active
periodic table explanation
as you count, the same one reappears
chemical family
contains similar characteristics involving reactivity; their location on the periodic table and their properties determines relationship; the number of valence electrons
transitional elements
d block; first D is third, but they don't start filling till the S has 4; inconsistency of quantum mechanics
ionization energy
is removing an electron's affinity energy; opposite
why nonmetals form negative ions
they gain electrons to form an octet