Chem semester exam

matter

anything that takes up space (volume) and has a mass

what is the absence of matter?

outer space

three states of matter

solid, liquid, gas

gas

indefinite volume, indefinite shape, particles are far apart. takes both shape and form of container

liquid

definite volume, indefinite shape, particles are apart but closer than gas

solid

definite volume and shape, particles are close

physical properties

characteristics of a substance that can be observed WITHOUT altering the identity of a substance

ex:dissolving, pH, melting/freezing point, color, odor, texture, solubility

chemical properties

characteristics of a substance that can be observed BY ALTERING the substance

ex: reactions, flammability, burning, rusting

intensive property

property that does NOT depend on the amount of matter present. (color, density, odor, texture, solubility)

extensive property

a property that DOES depend on the amount of matter present (mass and volume)

physical change

doesn't alter identity

Ex:phase change, break, tear

chemical change

alters identity

what are the 4 signs of a chemical change

\-formation of bubbles (gas)

\-release or absorption of heat

\-formation of a precipitate

\-color change

law of conservation of matter

matter can not be created nor destroyed

vapor

describes gaseous state of substance, generally liquid or solid at room temperature.

mixture

physical blend of two or more components that are not chemically combined.

heterogenous mixture

mixture that is not uniform in composition and components are not evenly distributed throughout the mixture

ex: salad, chicken noodle soup

homogeneous mixture

mixture that is uniform throughout. evenly distributed

ex: air, olive oil, stainless steel

solution

another name for homogenous mixture

phase

any part of a sample with uniform composition, homogenous has one phase, heterogeneous has two or more phases.

filtration

process that separates a solid from the liquid in a heterogeneous mixture

distillation

process used to separate components of a mixture using differences in boiling points. liquid is used to produce vapor, that is then condensed to liquid

how can mixtures be separated?

distillation and filtration

what are the two types of mixtures

heterogenous and homogeneous

element

simplest form in matter that has a unique set of properties. represented by symbols/letters.

compound

substance that contains two or more elements chemically combined in fixed proportions. compounds can be broken down. represented by formulas

chemical symbol

one or two letter word that represents an element

subscripts

written below the line, tells element number in each compound

periodic table

arrangement of elements in which the elements are separated into groups based on repeating properties.

period

horizontal row of periodic table, fill and restart valence electrons

group

vertical column on table, similar chemical and physical properties

reactant

present at start of reaction

product

substance produced from reaction

precipitate

solid that forms out of a liquid mixture

pure substances

made up of only one type of atom/molecule

ex: elements and compounds

two types of physical properties

extensive and intensive

scientific notation

n×10^y

n= a number 1-9

y= the power it is raised to, the number of times decimal moved

accuracy

measurement close to accepted value

precision

measurement you get every time you measure. (measurement reproducible)

what are significant figures and why are they important?

Significant figures are known digits in a number plus a last estimated digit

adding and subtracting sig figs

\-round to same number of decimal places as measurement w/ least number of places

ex:Ex: 123.25+46.0+86.257=255.5

multiplication and division sig figs

\-round answer to same number of sig figs as measurement with least sig figs

ex:Ex: 23.0x432x19=188,734 but with sf...190,000

how do you find density?

mass/volume

Tyndall effect

light scatters when passing through a colloid or very fine suspension

given data, how do you construct a graph and determine its slope?

\-give title using Y Axis vs. X Axis

\-label axes with measurement too

\-draw line of best fit through origin (unless otherwise specified), DON'T USE REAL DATA POINTS TO FIND EQUATION OF LINE

\-create key if necessary

\-fill up entire page

how to calculate percent error

percent error= (error) in absolute value form/ accepted value with this new number created multiplied by 100%

solute

substance being dissolved

solvent

substance doing the dissolving

dalton

\-atoms are neutral, no charge

\-Elements consist of very small indivisible particles called atoms

\-All atoms of an element are identical in mass and chemical behavior

\-Atoms of different elements can physically or chemically combine to form compounds

\-Chemical reactions occur when atoms are separated, joined or rearranged

\-Atoms of one element are never changed into atoms of another element as a result of a chemical reaction

\-Proved Law of Definite Proportions (specific substances always contain elements in the same ratio by mass) and Law of Conservation of Matter

Thompson

\-Showed that atoms of any elements have negative particles with a mass: electrons!

\-Plum Pudding Model: negative electrons balance out positive atoms

Rutherford

\-Used Gold Foil Experiment to find positively charged "core of an atom": nucleus

\-Found that the rest of an atom is empty space

bohrs planetary model

\-Suggested electrons orbit nucleus the way planets orbit the sun

\-More energy--further from nucleus

\-Electrons travel in a circular path

\-Electrons have their home (ground state)

\-Electrons absorb/release energy in quanta or photons by moving from higher to lower energy levels

\-Planck's Theory: energy released in packets

\-Worked great for hydrogen but no other element

cathode ray experiment

\-Negatively charged plate (cathode) emits an invisible ray which moves through the positively charged plate (anode)

\-Electric field: deflected away from negative plated towards positive plate, ray had a negative charge

\-Magnetic field: beam would bend in the presence of a magnet, ray had a mass

Milikans oil drop experiment

\-Millikan determined mass of oil drop from terminal velocity

\-Discovered the size of the charge of an electron

\-Determined that there was a smallest unit of charge, or that charge in quantized

gold foil experiment

\-rutherford

\-Shoot atoms through gold foil, occasionally one of the atoms would bounce back

\-Atom is composed of mostly empty space

\-Atoms have positive core called nucleus

\-Discovered that atoms are made up of mostly empty space, EXCEPT for the nucleus in the center

quantum mechanical model

\-no set electron location

\-Four quantum numbers to predict probable location of each electron in atom

\-Electrons do not have set positions, instead they exist in the electron cloud, orbitals simply approximate where certain electrons would be

what info does the atomic symbol give?

symbol of element, atomic number, number of protons in the nucleus, mass number of isotope with the total number of protons and neutrons (amu)

three subatomic particles

electrons (negative), protons (positive), neutrons (no charge)

mass number

total number of protons and neutrons in nucleus

isotopes

atoms that have the same number of protons but different number of neutrons (different mass)

\-chemically they are alike because they have the same number of protons and electrons

ion

an element with a different number of electrons and protons. due to loss or gain of electrons

neutral atom

no charge, regular mass number

average atomic mass *look at notes

weighted average of the atoms in a naturally occurring sample of the atoms in a naturally occurring sample of the element formula: (% abundance x mass #) + (% abundance x mass #) = answer in amu (practice problems???

how do you determine the charge an ion will take

\-Each atom wants 8 valence electrons in order to be an ion

\-Columns 1, 2 and 3 will lose electrons and be a + charged ion, or a cation

\-Columns 5, 6, 7 will gain electrons and be a - charged ion, or anion

\-Column 4 can lose 4 electrons (4+) or gain 4 (4-)

Frequency

number of wave cycles that pass a given point per unit of time

\-nu, ν

wavelength

distance between crests of a wave

\-lamda, λ

photons

quantum of light

high frequency is what size wave length?

shorter wavelength

lower frequency is what size wave length?

longer wave length

quantum

amount of energy needed to move an electron from one element to another

what are the two important equations for solving problems with wavelength, frequency, and energy?

E=hν

\-E: energy in Joules (J)

h: planck's constant, 6.63x10^-34 Joules x seconds

V: frequency

C=λν

\-C: speed of light, 3.0x10^8 m/s

\-ν= frequency(1/s, hertz)

\-λ=wave length (m)

what are the four quantum numbers in electron configurations?

1- energy level

2-shape of orbital (s,p,d,f)

3-3D orientation (xyz axes)

4-spin of electron, opposite spin

Aufbau principle

electrons occupy the lowest energy level first

pauli exclusion principle

two electrons occupying the same orbital must have opposite spins

hunds rule

each electron must occupy its own orbital before sharing with another electron

abbreviated configuration

start from noble gas from before

valence electrons

outermost electron in the highest energy level, will always be s and p orbitals

planks constant

number used to calculate the energy absorbed or emitted by a body based on frequency or radiation.

speed of light

3.0 *10^8 m/s

electromagnetic spectrum

\-gamma (highest energy)(short wave)(high frequency)

\-x rays

\-ultra violet

\-violet

\-blue

\-green

\-yellow

\-orange

\-red

\-infrared

\-microwaves

\-radar

\-radiowaves (lowest energy)(longest wave)(lowest frequency)

ultra

above

infra

below

quantum theory

energy is absorbed and emitted in discrete packets or energy called quanta or photons

How do you write complete electron configurations for ions?

Meaning there is a diff between electrons. Depending if its 2+ (2 less electrons) or 2- (2 more electrons) you just move the element backward from 14- 12 or forward 14-16

contribution of bohr model

atomic model, positive nucleus surrounded by electrons

Planck's quantum theory

energy is released in very small chunks, gives the chunk the number 6.63x10^-34

De Broglie duality of nature:

particles have wave properties (wave particle duality)

Schrodinger Wave Equations

use probability to find electron's location in the electron cloud

Heisenberg Uncertainty Principle

electrons act like particles, impossible to know exact velocity and position of a particle at the same time

bohr model vs quantum model

\-Bohr: absorption/emission of energy, orbitals

\-Quantum Mechanic Model: can't know position and velocity at the same time

mendeleev's periodic table

\-arranged rows by increasing atomic mass

\-arranged columns by chemical properties

\-left spaces for undiscovered elements

modern periodic table

arranged by atomic number

periodic law

when elements are arranged by increasing atomic number, there is a periodic repetition of physical and chemical properties

group 1

alkali metals

group 2

alkaline earth metals

transition metals

elements in the middle

group 3

boron family

group 4

carbon family

group 5

nitrogen family

group 6

oxygen family