Definitions Flashcards
Define an element.
An element is a substance that cannot be split into simpler substances by chemical means
Define a triad.
A triad is a 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
Define Newland’s Octaves.
Newland’s Octaves are arrangements of elements in which the first and the eight element, counting from a particular element, have similar properties
Define Mendeleev’s Periodic Law.
When elements are arranged in order of increasing atomic weight (relative atomic mass), the properties of the elements recur periodically, i.e. the properties displayed by an element are repeated at regular intervals in other elements
Define atomic number,
The atomic number of an atom is the number of protons in the nucleus of that atom
Define the modern Periodic Table.
The modern Periodic Table is an arrangement of elements in order of increasing atomic number
Define Modern Periodic Law
When elements are arranged in order of increasing atomic number, the properties of the elements recur periodically, i.e. the properties displayed by an element are repeated at regular intervals in other elements
Define mass number,
The mass number of an element is the sum of the number of protons and neutrons in the nucleus of an atom of that element
Define isotopes.
Isotopes are atoms of the same element, (i.e. they have the same atomic number) which have different mass numbers due to the different number of neutrons in the nucleus
Define relative atomic mass.
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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
What is the principle of mass spectrometry?
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
Define electron configuration.
The electron configuration shows the arrangement of electrons in an atom of an element
What is the Aufbau Principle?
When building up the electron configuration of an atom in its ground state, the electrons occupy the lowest available energy levels
What is Hund’s Rule of Maximum Multiplicity?
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
What is the Pauli Exclusion Principle?
The Pauli Exclusion Principle states that no more than two electrons may occupy an orbital and they must have opposite spin
