The Atom Flashcards
Nucleons
This is the collective name given to the total number of particles present in the nucleus of an atom (protons and neutrons)
Atomic number
This is the Total number of protons that are found in the nucleus of an atom (it also represents the total number of electrons orbiting the nucleus in the neutral atom) and is represented by the symbol Z.
Mass number
This is the collective sum of the number of protons and neutrons (nucleons) that are present in the nucleus of an atom and is represented by the symbol A.
Isotopes
These are atoms of an element that have the same number of protons, but different numbers of neutrons in the nuclei — that is, they had differing numbers of nucleons.
Energy level
This is an area of probability in which an electron would be found orbiting the nucleus of an atom and that these electrons would have energy typical of that region of probability.
Orbitals
These are areas within an energy level in which electrons are located. The orbitals do vary slightly in energy where S orbital will have the lowest energy within their level, then the P orbital, then the D orbital followed by the F orbital.
The Aufbau principal
The energy structure of a multi electron atom is obtained by filling the orbitals one electron at a time, in order of increasing energy starting with the lowest energy.
Pauli’s exclusion principle
Electrons are negatively charged which means that if electrons are placed close to each other, like in an orbital in an energy level – electrostatic forces of repulsion will be present between the elections causing them to have opposite spins.
Hunds rule of maximum multiplicity
When more orbitals than electrons are available within an energy level, then the electrons will tend to singularly occupy the orbitals before they form electron pairs.
Valence electrons
The number of electrons that are found in the highest energy level of an atom
Core electrons
The electrons that are present in the lower energy levels beneath the highest or valence energy level. These electrons will ensure that the lower energy levels are full.
Period
The number of the row which represents the highest energy level in which the valence electrons for an atom of a particular element will be found.
Valency
This is the number of electrons an atom must either lose or gain to achieve a filled outermost energy level and hence attain its most stable energy state.
Bonding pair
This is a shared pair of electrons that is common to both atoms that are involved in the chemical bond and are shared equally between both atoms in that bond.
Molecule
This is a combination of non metal atoms which are bonded covalently through electron sharing as a result of overlap of the outer most orbital forming bonding pairs of electrons.
