Hiedel Honors

Law of Conservation of Mass
mass is niether creater nor destroyed during ordinary chemical reactions or physical changes
Law of Definite Proportions
Chemical compounds contain the same elements in exactly the same proportions by mass reagrdless of the size of the sample or source of the compound
Law of Multiple Proportions
Two or more different compounds are composed of the smae two elements then the ratio of the masses of the second element combined with a certain mass of the first element is always a ration of small whole numbers
Smallest particle of an element that retains the chemical properties of that element
Nuclear forces
short-range proton-neutron, proton-proton, and neutron-neutron forces that hold the nuclear particles together
Atomic Mass
number of protons of each atom of that element
Average Atomic Mass
Weighted average of the atomic masses of the naturally occuring isotopes of an element
Avogadro’s Number
6.022 x 10^23 number of particles in one mole of a pure substance
Atoms of the same element that have different masses (different number of neutrons)
Mass Number
Total number of protons and neutrons that make up the nucleus of an isotope
Molar Mass
Mass of one mole of a pure substance i
amount of substance that contains as many particles as there are exactly 12 g of carbon-12
term for a specific isotope of an element
electromagnetic radiation

form of energy that exhibits wavelike behavior as it travles through space

Ex: X Rays, Ultaviolet, Infared, Microwaves, and Radiowaves;

Electromagnetic spectrum
All the forms of electromagnetic radiation make this up
continous spectrum
the emission of a continous range of frequencies of electromagnetic radiation
excited state
state in which an atom has a higher potential energy than in its ground state
defined as the number of waves that oass a given point in a specific time, usually one second
Ground State
lowest energy state of an atom
line-emission spectrum
when a narrow beam of the emitted light was shined through a prism it was seperated into four specific colors of the visible spectrum
Photoelectric Effect
Refers the emission of electrons from a metal when light shines on the metal
Particle of Electromagnetic radiaiton having sero mass and carrying a quantum of energy
Minimum quantity of energy that can be lost or gained by an atom
Distance between corresponding points on adjacent waves
Angular Momentum Quantum Number
symbolized by l, indicates the sahpe of the orbital
Heisenberg Uncertainity Principle
States that it is impossible to determine simultaneously both the position and velocity og an electron or any other particle
Magnetic Quantum Number
symbolized by m, indicates the orientation of an orbital around the nucleus
three-dimensional region around the nucleus that indicates the probable location of an electron
Principal Quantum Number
symbolized by n, indicates the main energy level ocupied by the electrons
Quantum Numbers
Specify the properties of atomic orbitals and the properties of electrons in orbitals
Quantum Theory
Describes mathematically the wave properties of electrons and other very small particles
Spin Quantum Number
Only two possible values (+.5, -.5) indicates the two fundamental spin states of an electron in a orbital
Aufbau Principle
An electron occupies the lowest-energy orbital it can receive
Electron configuration
arrangement of elctrons in an atom, lowest energy arrangement
Highest Occupied Level
Electron containing main energy level with the highest principal quantum number
Hund’s Rule
Orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin state
Inner-Shell Electrons
Electrons that are not in the highest-occupied energy level
Noble Gases
Group 18 elements
Pauli Exclusion Principle
No two electrons in the same atom can have the smae set of four quantum numbers
Orbital Notation
unoccupied orbital = _ with name written underneath it; orbital with one or more electron has an arrow representing each seperate electron
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