The Periodic Table Flashcards
Element
Substance that cannot be split into simpler substances by chemical means
Triad
Group of three elements with similar chemical properties in which the atomic weight ( relative atomic mass) of the middle element is approximately equal to the average of the other two
Newlands octaves
Arrangements of elements in which the first and the eight element, counting from a particular element have similar chemical properties
Mendaleevs periodic law
When elements are arranged in order of increasing atomic weight (relative atomic mass) the properties of the elements recur periodically. This means that the properties displayed by an element are repeated at regular intervals in another element
Atomic number
The number of protons in the nucleus of that atom
Modern periodic table
Arrangement of elements in order of increasing atomic number
Modern periodic law
When elements are arranged in order of increasing atomic number, the properties of the elements recur periodically. This means that the properties displayed in one element are repeated at regular intervals in other elements
Mass number
The sum of the number of protons and neutrons in the nucleus of an atom of that element
Isotopes
Atoms of the same element ( they have the same atomic number) which have different mass numbers due to a different number of neutrons in the nucleus
Relative atomic mass
The average of the mass numbers of the isotopes of the element
As they occur naturally
Taking their abundances into account
And expressed on a scale in which the atoms of the carbon -12 isotope have a mass of exactly 12 units
Principle of mass spectrometry
Charged particles moving in a magnetic field are deflected to different extents according to their masses and are thus separated according to their masses
Electron configuration
Shows the arrangement of electrons in an atom of an element
Aufbau principle
When building up the electron configuration of an atom in its ground state, the electrons occupy the lowest available energy levels
Hunds rule of maximum multiplicity
States that when two or more orbitals of equal energy are available, the electrons occupy them singly before filling them in pairs
Pauli exclusion principle
States that no more than two electrons may occupy an orbital and they must have opposite spin