Chapter 5 Electrons and Structure Flashcards
Shells, sub-shells and orbitals
Electrons are arranged in electron shells (energy levels)
The shells have sub-shells(sub-level)
Each Shell/sub-shell is made up of electron orbitals which can each hold 2 electrons.
Orbital definition
regions of space in which the electrons most likely to be found.
the electrons have opposite spins i.e. clockwise + anticlockwise.
this helps to minimise the repulsion.
Hund’s rule
every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied and all electrons in singly occupied orbitals have the same spin.
Aufbau’s Principle
Electrons enter the lowest energy orbital available.
Ions
The highest energy level electrons are lost when an ion is formed.
Note that 4s electrons are lost before 3d, as once 4s and 3d are occupied 4s moves above 3d.
What are the 4 atomic orbitals
Each shell from n = 1 has one s-orbital
Each shell from n = 2 has three p-orbitals
Each shell from n = 3 has five d-orbitals
Each shell from n = 4 has seven f-orbitals
Two forms of electronic configuration
Normal electron configuration is written in full however shorthand can be used aswell. This is done by writing an element from group 8 and adding the rest of the electrons.
Ionic bonding
is the electrostatic attraction between positvie and negative ions. It holds together cations and anions in ionic compounds.
Structure of ionic compounds
Has a giant ionic lattice structure containing billions of ions. Each Positive ion is surrounded by 6 negative ions and the opposite for each negative ion it is surrounded by 6 positive ions.
Properties of ionic compounds
Solid at room temp. At room temp there is insufficient energy to overcome the strong electrostatic forces of attraction between the oppositely charged ions in the giant ionic lattice. High tempers are needed for a lot of energy to overcome the strong electrostatic attraction between ions. High melting and boiling points.
Many ionic compounds dissolve in polar solvents such as water. They break down the lattice and surround each ion in solution.
An ionic compound does not conduct electricity when solid but does when in solution or liquid or molten.
Two process of solubility
The ionic lattice must be broken down
water molecules must attract and surround the ions.
Covalent bond definition
A strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
Lone pair of electrons
Paired electrons that are not shared are called lone pairs.
Orbital overlap
the shared pair of electrons is attracteed to the nuclei of the both the bonding atoms.
The bonded atoms often have outer shells with the same electron structure as the nearest noble gas.
Covalent bonds are localised
with an ion it attracts oppositely charged ions in all directions, resulting in a giant ionic lattice structure containing billions of ions.
in covalent, the attraction is localised and acts between the shared pair of electrons and the nuclei of the two bonded atoms. This creates molecules.
