Studied by 24 peoplemolecules in nucleus
protons and neutrons
mass number
number of neutrons in nucleus
atomic number
number of protons in nucleus
isotopes
same number of protons and electrons but different number of neutrons
average atomic mass
based on the percentage of isotopes found in nature
valence electrons
electrons in the outermost shell (can be easily shared, gained or lost)
core electrons
electrons in the inner shell
atomic spectra
the electromagnetic emission from atoms and molecules
spectroscopy
a technique measuring electromagnetic emissions that is widely used in chemical analysis and in studies of the properties of atoms, molecules, ions, etc.
wave mechanical model
modern model of the atom, atoms have electrons in "orbitals" that are like clouds around the nucleus
quantum numbers
specify the properties of atomic orbitals and the properties of electrons in orbitals
pauli expulsion principle
an atomic orbital may describe at most two electrons, each with opposite spin direction
hund’s rule
electrons do not pair up until they have to
aufbau principle
An electron occupies the lowest-energy orbital that can receive it
noble gas notation
shortcut→ find the closest noble gas (column 18) with fewer electrons than the element then finish configuration
transition elements
group 3-12
transition element properties
elements that have high melting points, often paramagnetic, tend to form salts when reacted w/ halogens ex; iron, copper, gold, silver, and titanium
electronegativity
a measure of the ability of an atom in a chemical compound to attract electrons
ionization energy
the amount of energy required to remove an electron from an atom
alpha decay
a nuclear reaction in which an atom emits a ________ particle consisting of two protons and two neutrons; this increases the atomic number by 2 and the mass number by 4.
beta decay
a nuclear reaction in which a neutron changes into a proton and into an electron, and the atoms emits a ______ particle, which is the electron; this increases the atomic number of the atom without changing the mass.
gamma radiation
electromagnetic radiation emitted during radioactive decay and having an extremely short wavelength
covalent bond
a chemical bond that involves sharing a pair of electrons between atoms in a molecule
dipole-dipole attraction
attractive force resulting when polar molecules line up so that the positive and negative ends are close to each other
electrostatic repulsion
describes a force between particles with opposite electrical charges that causes them to push apart from one another
hybridization
several atomic orbitals mix to form the same total number of equivalent hybrid orbitals
hydrogen bond
a relatively weak bond formed between any hydrogen atom (which is covalently bound to a nitrogen or oxygen atom) and a nitrogen or oxygen with an unshared electron pair
ionic bond
formed when one or more electrons are transferred from one atom to another; metal and nonmetal
london dispersion forces
the intermolecular attractions resulting from the constant motion of electrons and the creation of instantaneous dipoles
metallic bond
a bond formed by the attraction between positively charged metal ions and the electrons around them
pi bond
when two p orbitals line up in parallel and electron clouds overlap. it exsits over a single bond.
resonance structure
a structure that occurs when it is possible to draw two or more valid electron dot structures that have the same number of electron pairs for a molecule or ion
stable octet
the arrangement of eight electrons in the outermost shell of an atom
sigma bond
a bond formed when two atomic orbitals combine to form a molecular orbital that is symmetrical around the axis connecting the two atomic nuclei
van der waals forces
a slight attraction that develops between the oppositely charged regions of nearby molecules
VSERP
valance electron pair repulsion model / unshared electron pairs around the central atom
binary compound
ionic compounds when they are composed of only two different kinds of atoms
coefficient
a number in front of a chemical formula in an equation that indicates how many molecules or atoms of each reactant and product are involved in a reaction.
emperical formula
simplest whole # ration of atoms in a compound
formula mass
the sum of the average atomic masses of all the atoms represented in the formula of any molecule, formula unit, or ion
molecular mass
the sum of the masses of all the atoms in a molecule
law of definite composition
chemical compounds are composed of a fixed ratio of elements as determined by mass.
law of multiple proportions
whenever two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers
net ionic equation
includes only those compounds and ions that undergo a chemical change in a reaction in an aqueous solution
percentage composition
the percentage by mass of each element in a compound
polyatomic ion
a covalently bonded group of atoms that has a positive or negative charge and acts as a unit
products
the elements or compounds produced by a chemical reaction.
reactants
a substance that takes part in and undergoes change during a reaction
stock system
a method for naming ions of elements that can form more than one possible positive charge by using a roman numeral after the ion name to denote the ion's charge
ternary compound
a compound that consists of three or more elements, usually containing
true formula
chemical formula that indicates the actual number of atoms of each element in one molecule of a substance
atmosphere
Layers of different gases that surround the Earth.
atmospheric pressure
the pressure exerted by atoms and molecules in the atmosphere surrounding Earth, resulting from collisions of these particles with objects
greenhouse effect
natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases
manometer
a device used to measure the pressure of a sample of gas in a container.
boyle’s law
PV = k
charles’s law
V/T = k
combined gas law
P1V1/T1=P2V2/T2 (constant n)
ideal gas law
PV = n R T
dalton's law of partial pressures
total pressure of a gas is equal to the sum of the partial pressure of the component gases
graham's law
rate of diffusion of a gas is inversely proportional to the square root of its molecular weight
kinetic-molecular theory
a theory that explains that the behavior of physical systems depends on the combined actions of the molecules constituting the system
mercury barometer
an instrument that measures changes in air pressure, consisting of a glass tube partially filled with mercury, with its open end resting in a dish of mercury
ozone
a form of oxygen that has three oxygen atoms in each molecule instead of the usual two
pascal
the SI unit of pressure equal to one newton per square meter
standard pressure
1 atm or 101.3 kPa
standard temperature
One atmosphere and 273 K.
torr
the force per unit area exerted by the gas on its container, usually measured in atmospheres
acidic anhydride
a nonmetallic oxide that, when placed in water, reacts to form an acid solution
aeration
air is forced through the water to release unwanted gases, which reduces odor and improves taste
alloy
a mixture of two or more metals
boiling point
the temperature at which a liquid changes to a gas
brownian movement
kinetic energy spreads small suspended particles throughout the cytoplasm of the cell
colligative property
a property of a solution that depends on the number, not the identity, of the solute particles
concentrated
describes a solution that has a relatively large amount of dissolved solute
critical pressure
the lowest pressure at which the substance can exist as a liquid at the critical temperature
critical temperature
the temperature above which the substance cannot exist in the liquid state
crystal
an orderly, three-dimensional pattern of ions or atoms in a solid
deliquescent
compounds that remove sufficient water from the air to dissolve completely and form solutions
dilute
to lessen the concentration, force, or purity of by adding something
dynamic equilibrium
result of diffusion where there is continuous movement of particles but no overall change in concentration
endothermic
a chemical reaction that absorbs energy (heat)
efflorescent
hydrated crystals that lose the water of hydration on exposure to air at ordinary temperatures
exothermic
a chemical reaction that releases energy (heat)
heat of fusion
amount of energy required to change a substance from the solid phase to the liquid phase
heat of vaporization
the amount of energy required for the liquid at its boiling point to become a gas
"heavy" water
water containing an elevated concentration of molecules with deuterium
deuterium
an isotope of hydrogen with one proton and one neutron in the nucleus having an atomic weight of 2.014
hydrate
a compound that has a specific number of water molecules bound to its atoms
le chatelier's principle
states that if a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress
melting point
the temperature at which a solid becomes a liquid
miscible
describes two liquids that are soluble in each other
immiscible
liquid solutes and solvents that are not soluble in each other
molality
the concentration of a solution expressed in moles of solute per kilogram of solvent
molarity
a common measure of solute concentration, referring to the number of moles of solute per liter of solution
mole fraction
the ratio of the moles of solute in solution to the total number of moles of both solvent and solute
normality
gram equivalent weight of solute per liter of solution, often denoted by N
phase equilibrium
when the rates of evaporation and condensation equalize
polarity
a lack of electrical symmetry in a molecule; charge differences on opposite ends of a structure
saturated
unable to dissolve any more solute
Note
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