Chapter 4_ The Periodic Table Flashcards
Aufbau Principle
When building up the electron configuration of an atom in its ground state, the electrons occupy the lowest available energy levels.
The Modern Periodic Table
An arrangement of elements in order of increasing atomic number.
Electron configuration
shows the arrangement of electrons in an atom of an element.
Isotopes
Are atoms of the same element which have different mass numbers due to the different number of neutrons in the nucleus.
The Pauli Exclusion Principle
States that no more than two electrons may occupy an orbital and they must have opposite spin
Atomic Number
The number of protons in the nucleus of an atom.
Mendeleev’s Periodic Law
When elements are arranged in order of increasing atomic weight, the properties of the elements recur periodically.
Newland’s Octaves
Are arrangements of elements in which the first and eight element, counting from a particular element, have similar properties.
Hund’s 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.
Modern Periodic Law
When elements are arranged in order of increasing atomic number, the properties of the elements recur periodically.
A Triad
A group of three elements with similar chemical properties in which the atomic weight of the middle element is approximately equal to the average of the other two
An Element
A substance that cannot be split into a simpler substance by chemical means.
The principle of mass spectrometry
is that charged particles moving in a magnetic field are deflected to different extents according to their masses and are thus separated according to these masses.
Mass Number
The sum of the number of protons and neutrons in the nucleus of an atom of a specific element.
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.
