173 terms

Chem 101

anything that has mass and occupies space
two things loosely joined together
a substance formed by chemical union of two or more elements or ingredients in definite proportion by weight
the study of composition, structure, properties and reactions of matter
substance that always has the same composition and properties wherever it is found
scientific method
observations, hypothesis, experiment, theory
measured numbers
the numbers you obtain when you measure a quantity
exact numbers
those obtained by counting items or from a definition that compares two units in the same measuring system
The ability to do work
any activity that requires energy
Potential energy
stored energy. Types: gravitational, chemical, electrostatic
Kinetic energy
the energy of motion. types: mechanical, thermal, electrical
energy that flows from a warmer object to a cooler one
SI unit of energy and work
amount of energy needed to raise the temperature of 1g of water by 1 degree Celsius
how hot or cold a substance is compared to another substance
1.8*(temperature Celsius) + 32
Specific heat
amount of heat needed to raise the temperature of exactly 1g of substance by exactly 1 degree Celsius
Pure substance
matter that has a definite composition
the simplest pure substance, contains only one material
a pure substance that contains 2 or more elements all in the same proportions
two or more substances that are physically mixed but not chemically combined
homogeneous mixture, solution
composition is uniform
heterogeneous mixture
mixture where composition is not uniform
physical properties
characteristics that can be observed without affecting the identity of a substance
physical change
change of a substance where its state or apperance will change but its composition remains the same
chemical properties
properties that describe the ability of a substance to change into a new substance
chemical changes
changes in a substance where the substance is converted into one or more new substances in which have different chemical and physical properties
Heat of fusion
energy needed to separate particles of a solid during melting
Heat of fusion for water
334 Joules = 80 calories for 1g of H2O
Heat needed to melt
mass * heat of fusion
heat of sublimation for water
2590 J = 620 calories for 1 gram of H2O
Heat of vaporization for water
2260 Joules = 540 calories for 1g of H2O
Heat needed to vaporize or condense
mass * heat of vaporization
Heat of a reaction
heat of products minus heat of reactants
representative elements
an element in an "A" group in the periodic table; as a group these elements display a wide range of physical and chemical properties. In their atoms, the s and p sublevels in the highest occupied energy level are partially filled
transition elements
groups of elements in the modern periodic table that are designated with a B(1B through 8B) and are further divided into transition metals and inner transition metals
alkali metals
Group 1, 1 electron in outer level, very reactive, soft, silver, shiny, low density; Lithium, Sodium, Potassium, Rubidium, Cesium, Francium
alkaline earth metals
metallic elements in group 2 of the periodic table which are harder than the alkali metals and are also less reactive
noble gasses
non-metals, group 18, the most non-reactive elements
semiconductors, border the zigzag line, shiny, brittle, hard, at high temp- good conductors of electric current
left of the zigzag line, shiny, malleable, ductile, good conductors of electric current, good conductors of thermal energy
elements that are usually dull in appearance, poor conductors of heat and electricity, gases at room temperature
group 17; contains nonmetals; 7 electrons in its outermost energy level; very reactive; poor conductors of electric current; never in its uncombined form in nature; combine with most metals to form salts
smallest particle of an element that retains the characteristics of that element
subatomic particles
smaller bits of matter that atoms are composed of
negatively charged particles in an atom
positively charged particles in an atom
where protons are contained in the atom
a particle contained in the nucleus of the atom, it is neutral
proton mass
1.7*10^-24 g (also about the mass of a neutron)
electron mass
9.1*10^-28 g, 1/1800 of H atom
atomic mass unit (amu)
one twelfth of the mass of a carbon atom with six protons and six neutrons
1 amu
1 amu
atomic number
# of protons in an atom
mass number
protons + neutrons
atoms of the same element that have different numbers of neutrons
atomic mass
the weighted average of all the naturally occurring isotopes of that element
atomic spectrum
the spectrum created when the light emitted from a heated element is passed through a prism
levels within each energy level that contain electrons with identical energy
a region in an atom where there is the highest probability of finding an electron, they are sub-shells of the n shells, each orbital can have a max of 2 electrons. orbitals with the same value of n form a shell, and orbitals on the same energy level are called degenerate
atomic radius
distance from nucleus to the valance electrons
ionization energy
the energy needed to remove the least tightly bounded electron from an atom in the gaseous state
cathode ray tubes
ray moves with electric and magnetic field, made of particles
alpha particle
2 protons, 2 neutrons, mass number of four, atomic number of 2, charge of 2+
beta particle
high energy electron that is emitted when a neutron in an unstable nucleus changes to a proton charge of 1-, mass number of 0
positron particle
produced by an unstable nucleus when a proton is transformed into a neutron and a positron. positive 1+ charge, mass number of 0, (B+) antimatter
an isotope that emmitts radiation
a particle that is the exact opposite of another particle
Gamma rays
high-energy radiation, released when an unstable nucleus undergoes a rearrangement of its particles to give a more stable, low energy nucleus. Gamma rays are often emitted along with other types of radiation. No mass or charge
Radioactive decay
when a nucleus spontaneously breaks down by emitting radiation
converting stable, non-radioactive isotopes into radioactive ones by bombarding the nucleus by high speed particles to produce radioisotopes
3.7*10^10 disintegrations per second
1 disintegration per second
radiation absorbed dose (rad)
measures amount of radiation absorbed by a gram of material
Gray (Gy)
100 rads
radiation equivalent in humans (rem)
measures biological effects of different kinds of radiation. rem = rad x factor
sivert (sv)
100 rems
the amount of time it takes for one half of a sample to decay
decay curve
diagram of the decay of a radioactive isotope
smallest quanta of electromagnetic radiation
atomic energy
energy generated when splitting an atom
nuclear fission
splitting the nucleus of an atom
chain reaction
the rapid increase in number of high-energy neutrons capable of splitting
Nuclear fusion
2 small nuclei combine to form a larger nucleus. Mass is lost and energy is released. fusion happens in the sun, requires 100,000,000 degree Celsius
mass of substance left after a certain amount of time
mass * (.5)^(how many half lives have passed)
ground state
the lowest energy state of an atom
excited state
an electron moves up a level
period number
the number of electrons allowed in an energy level
octet rule
the tendency for atoms to attain a noble gas electron configuration
ionic compound
a compound where an atom of one element lose valance electrons and the atoms of the other element gain valance electrons. electrolytes (ions dissolve in solution) metal + nonmetal, cation + anion, polar, conductive in solute or melted
covalant compound
a bond between elements where the elements share valance electrons. no electrolytes, do not conduct, no ions, two nonmetals, compounds do not break when dissolved
an atom or group of atoms having an electrical charge because of a loss or gain of electrons. formed in ionic bonding
positively charged ions formed when metals in ionic compounds lose their valance electrons, named by the element
negatively charged ions formed when nonmetals in ionic compounds gain valance electrons from metals, named with an ide
volume of ions
much smaller for metals and larger for nonmetals
polyatomic ion
a group of atoms that has an ionic charge. most are nonmetal covalent bonds with oxygen. generally stick together and behave as if it were one atom
covalent compound
what is formed when atoms of two nonmetals achieve stability by sharing electrons (creates a covalent bond)
what is formed when two or more atoms share electrons
resonance structures
when two or more electron-dot formulas can be written for a compound
Naming covalent compounds
1st nonmetal: element name
2nd nonmetal: prefix-name-ide
Covalent prefixes
mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca
the attraction of an atom for valence electrons in a chemical bond
nonpolar covalent bond
a bond between atoms with identical or very similar electronegativity values
polar covalent bond
when shared electrons are unequal in electronegativity
a polar covalent bond that has a separation of charges +----> indicates a dipole
valence-shell electron-pair repulsion (VSEPR) theory
indicates that the electron groups will move asw far apart as possible to reduce repulsion between the negative charges
180 degrees
120 degrees
Trigonal Planar
120 degrees
Tetrahedral (pyramid)
109.5 degrees
Trigonal pyramidal
107 degrees
bent (3-D)
105 degrees
polar molecule
one end of the molecule is more negatively charged than another end
dipole-dipole attractions
attractive forces that occur between the positive end of one molecule and the negative end of another
hydrogen bond
a strong dipole-dipole attraction between polar molecules created when a hydrogen atom is attached to fluorine, oxygen or nitrogen
dispersion forces
very weak attractions that occur between nonpolar molecules
atoms in the reacting substances in a chemical reaction
results of a reaction
chemical reaction
the process by which a chemical change takes place
chemical equation
a shorthand way to represent a chemical reaction using chemical formulas to indicate the reactants, products and coefficients to show reacting ratios
balanced equation
the final form of a chemical equation that shows the same number of atoms of each element in the reactants and products
combination reaction
a reaction in which reactants combine to form a single product
decomposition reaction
a reaction in which a single reactant splits into two or more simpler substances
single replacement reaction
a reaction in which an element replaces a different element in a compound
double replacement reaction
a reaction in which parts of two different reactants exchange places
a group of atoms, molecules or formula units that contain 6.02x10^23 of these items. One mole of any element always contains Avogadro's number of atoms
Avogadro's number
the number of items in a mole; equal to 6.02x10^23
formula units
the group of ions represented by the formula of an ionic compound
molar mass
the mass in grams of one mole of an element equal numerically to its atomic mass. The molar mass of a compound is equal to the sum of the masses of the elements in the formula
mole-mole factors
a conversion factor that relates the number of moles of two compounds derived from the coefficients in an equation
theoretical yield
the maximum amount of product that a reaction can produce from a given reactant
actual yield
actual amount of product produced by a reaction
percent yield
the ratio of the actual yield of a reaction to the theoretical yield possible multiplied by 100%
Bonding (intramolecular) forces
covalent(sharing electrons), ionic(loosing, gaining electrons)
Attractive (intermolecular) forces
hydrogen, dipole-dipole, dispersion
limiting reactants
the reactant used up during a chemical reaction-it limits the amount of product that can form
excess reactant
the reactant that remains when the limiting reactant is used up in a reaction
Exothermic reaction
a reaction that releases energy in the form of heat
endothermic reaction
A reaction that ABSORBS energy in the form of heat
activation energy
the minimum amount of energy required to start a chemical reaction
heat of reaction
the quantity of energy released or absorbed as heat during a chemical reaction. each product/reactant = moles*heat of formation
oxidation (OIL)
the loss of electrons by a substance. Biological oxidation may involve the addition of oxygen or loss of hydrogen
oxidation/reduction reaction
a reaction in which the oxidation of one reactant is always accompanied by the reduction of another reactant. Provides us with energy from food, provides electrical energy in batteries, occurs when iron rusts, transfer electrons from one reactant to another
reduction (RIG)
the gain of electrons by a substance. Biological reduction may involve the loss of oxygen or gain of hydrogen
Heat of formation
the amount of heat required to form a substance
activated complex
a high energy transitional structure in a chemical reaction where old bonds are breaking and new bonds are forming
What kind of energy does temperature measure?
Boyle's Law

a gas law stating that the pressure of gas is inversely related to the volume when temperature (K) and amount (moles) do not change
Charle's law

a gas law stating that the volume of a gas changes directly with a change in Kelvin temperature when pressure and amount (moles) of the gas do not change
273 + K
Dalton's Law

a gas law stating that the total pressure exerted by a mixture of gasses in a container is the sum of the partial pressures that each gas would exert alone
Avogadro's law
n/V(or P)=n/V(or P)

a gas law that states the volume of a gas is directly related to the number of moles of gas when pressure and temperature do not change
Gay-Lussac's Law

a gas law stating that the pressure of a gas changes directly with a change in Kelvin temperature when the number of moles of a gas and its volume do not change
Ideal Gas Law
Ideal gas constant
atm R=.0821, torr/mmHg R=62.36, kpa R=

a numberical value that relates the quantities in the ideal gas law
Combined Gas Law

a relationship that combines several gas laws relating pressure, volume and temperature
Dalton's Law of partial pressure
Pgas=(mole fraction)*(P_Total)
Four variables of the state of a gas
Volume, Pressure, Temperature, Moles (n)
the amount of force applied to an area, P=F/Athe force exerted by gas particles that hit the walls of a container
Normal atmospheric pressure at sea level
1atm or 760 torr/mmHg
used to measure the difference in pressure between atmospheric pressure and pressure of a gas
the pressure exerted by a column of mercury 760 mm high
atmospheric pressure
the pressure exerted by the atmosphere
direct relationship
a relationship in which two properties increase or decrease together
inverse relationship
a relationship in which two properties change in opposite direction
kinetic molar theory of gas
a model used to explain the behavior of gasses
molar volume
a volume of 22.4L occupied by 1 mole of gas at STP conditions of 0 degrees Celsius and 1atm
partial pressure
the pressure exerted by a single gas in a gas mixture
vapor pressure
the pressure exerted by the particles of vapor above a liquid
1 atm and 0 degree Celcius/273 Kelvin