Physical Chemistry Definitions Flashcards
Atomic / Proton number
Number of protons in the nucleus of an atom.
Mass / Nucleon number
Sum of protons and nucleus in the nucleus of an atom.
Isotopes
Atoms of an element that have the same number of protons but different number of neutrons and hence different nucleon numbers.
S orbitals
Orbital that is spherically symmetrical about the nucleus. The larger the principal quantum number, the orbitals get larger and more diffused.
P orbitals
Three dumbbell shaped orbitals, mutually at right angles to each other. All three orbitals are degenerate, ie have the same energy.
d orbitals
d orbitals have different shapes
First Ionisation Energy
The energy needed to remove one mole of electrons from one mole of the gaseous atoms to form one mole of singly charged gaseous cations.
Relative isotopic mass of an isotope
The mass of one atom of the isotope to 1-12th the mass of one atom of C-12 isotope
Relative atomic mass of an element
The average mass of one atom of the element to 1-12th the mass of one atom of C-12 isotope
Relative molecular mass of a substance
The average mass of one molecule of the substance to 1-12th the mass of one atom of C-12 isotope
Relative formula mass of a substance
The average mass of one formula unit of the substance to 1-12th the mass of one atom of C-12 isotope
One mole
The amount of substance which contains the same number of particles as there are atoms in exactly 12g of C-12
Avogadro’s law
Equal volumes of all gases under the same conditions of temperature and pressure contain the same number of atoms/molecules.
Empirical formula
The simplest formula that shows the relative number of atoms of each element present in a compound.
Molecular formula
The actual number of atoms present in one molecules of the compound
Metallic bonds
Strong electrostatic forces of attraction between the metal ions and the ‘sea’ of delocalised electrons in a giant metallic structure.
Ionic bonds
Strong electrostatic forces of attraction between cations and anions in the crystal lattice of an ionic solid
Covalent bond
Strong electrostatic forces of attraction between a shared pair of electrons and two positively charged nuclei