Chemistry Final Semester 1

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chemistry

the study of matter and how it reacts with energy on a molecular level

entropy

the amount of disorder between molecules in a substance

matter

anything that takes up space

mole

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

law

an observed fact

atom

basic unit of an element

isotope

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

photon

dual nature of light

frequency

number of vibrations produced per second in Hertz

inert

non reactive

ion

atom that either gains or loses 1 or more electrons

valence electrons

electrons on outer orbital of atom; highest energy level

solid

lower level of entropy where molecules vibrate around a fixed point

liquid

higher level of entropy than a solid where molecules flow freely

gas

higher level of entropy that a liquid where molecules flow freely

plasma

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

units

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

mendeleyev

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

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