Thermochemistry Definitions Flashcards
Atomic Radius
The distance between the middle of the nucleus to the outermost electron
Electronegativity
The ability of an atom to attract electrons to itself
Ionisation energy
The amount of energy required to remove 1 mole of electrons from 1 mole of atoms in the gaseous state
What is the periodic table trend for electronegativity?
Electronegativity increases across the periodic table (to the right), and decreases down the periodic table
What is the periodic table trend for atomic radius?
Atomic radius decreases across the periodic table (to the right), and increases down the periodic table
What is the periodic table trend for ionisation energy?
Ionisation energy increases across the periodic table (to the right), and decreases down the periodic table
Nuclear charge
The number of protons within the nucleus
Shielding
When inner electron shells reduce the electrostatic force from the nucleus, reducing the force experienced by valence electrons
Hydrogen bonding
Hydrogen acts like a proton when bonded with O, N, or F, and becomes so positively charged that it is strongly attracted to the lone electron pairs on the O, N, or Fs on neighbouring molecules
Temporary dipole-dipole interactions
Instantaneous attractions that develop due to the bunching up of electrons, thus creation of positive and negative dipoles, within molecules
What types of molecules experience temporary dipole-dipole interactions?
All of them
Permanent dipole-dipole interactions
Unbalanced differences in electronegativities over the molecules generate positive and negative dipoles that have an electrostatic attraction between them
What types of molecules experience permanent dipole-dipole interactions?
Polar molecules only
Octahedral
6 regions of electron density
6 regions bonded
0 regions lone
Square pyramidal
6 regions of electron density
5 regions bonded
1 region lone
