1 - atomic strcuture Flashcards
atomic number (Z)
the number of protons in the nucleus of an atom of that element
mass number
the sum of the number of protons and the number of neutrons in the nucleus of that atom
isotopes
atoms of the same element with different masses
relative atomic mass (Ar)
the weighted mean mass of an atom of an element compared to 1/12 of the mass of an atom of carbon-12
relative isotopic mass
the mass of an individual atom of a particular isotope relative to 1/12 of the mass of an atom of carbon-12
molecular ion peak
the peak with the highest m/z ratio in the mass spectrum, the M peak
quantum shell
defines the energy level of an electron
orbital
a region of space with a high probability of finding an electron
can hold up to two electrons with opposite spins
electronic configuration
shows the number of electrons in each sublevel in each energy level of an atom
Hund’s rule
states that electrons will occupy the orbitals singly before pairing takes place
Pauli Exclusion Principle
states that two electrons cannot occupy the same orbital unless they have opposite spins. Electron spin is usually shown by the use of upward and downward arrows
first ionisation energy
the energy required to remove an electron from each atom in one mole of atoms in the gaseous state
second ionisation energy
the energy required to remove an electron from each singly charged positive ion in one mole of positive ions in the gaseous state
groups
vertical columns in the periodic table
periods
horizontal rows in the periodic table
