Terms Flashcards
Law of definite proportions
Any sample of a compound always has the same composition
Atomic theory
All matter is made of indivisible particles call atoms
Law of multiple proportions
Mass ratio for one of the elements in a compound that combines with a fixed mass of another element can be expressed in small whole numbers
Mole
The SI unit for measuring a substance
Anode
An electrode through which electrons enter a metal
Cathode
An electrode through which electrons leave a metal
Alpha particle
Positively charged particle produced by some nuclear disintegration a
Atomic number
Number of protons in an atom
Mass number
Total number of protons and neutrons in an atom
Coulomb’s law
The force between two charged particles is inversely proportional to the square of the distance between them
Isotope
One of two of more atoms of the same elements with different numbers of neutrons
Radioisotope
An unstable atom that undergoes radioactive decay
Quantum number
A number with certain definite values
Pauli exclusion principle
A maximum of two electrons can occupy each orbital and these electrons must have different spin quantum numbers
Aufbau principle
Electrons in an atom will occupy the lowest energy orbitals possible
Hund’s rule
The most stable arrangement of electrons is that with the maximum number of unpaired electrons, all with the same spin quantum number
Periodic law
The physical and chemical properties of elements are periodic functions of their atomic numbers
Period
A series of elements that from a horizontal row in the periodic table
Group
A series of elements that from a vertical column in the period table
Metal
An element that is a good conductor of electricity
Transition metals
Elements in groups 3 through 12
Nonmetal
An element that is a poor conductor of electricity
Semiconductor
A crystalline material with intermediate electrical conductivity
Main group elements
Elements belonging to groups 1, 2, and 13 through 18 in the periodic table and having very regular electron configurations
