Chapter 5 Flashcards
What are shells
Energy levels
Energy increases as shells increase
Shell number = principal quantum number
Atomic orbital
A region around the nucleus where there is a high probability of finding an atom
can hold 2 electrons, with opposite spins
S p d f
S orbitals
One sphere
Greater the shell number, the greater the radius of the sphere
P orbitals
Dumbbell shape
3 orbitals at right angles to each other
X y z
Each shell from n = 2 has 3 p orbitals
D orbitals
N=3
5 orbitals
F
N=4
7 orbitals
Orbitals fill in order of increasing energy
The new type of sub shell added has a higher energy
The highest energy level in the third shell overlaps with the lowest energy level in the 4th shell
Why do electrons pair with opposite spins
Electrons are negative and repel each other
They have a property called spin
Electrons in an orbital need to have opposite spins
This helps to counteract the repulsion between the negative charges f the electrons
Electrons in box model rule
Fill up each orbital before pairing
Shorthand electron configuration
Uses Nobel gas
(He)2s1
Sub shells in periodic table
S - 2 groups
P - last 6 groups
D - transition metals
F - below
Ions of d block
The energy levels of 4s and 3D are close
Once 3D is filled, it’s energy levels fall below 4s
- 4s fills and empties before 3D
Wha is ionic bonding
The electrostatic attraction between positive and negative ions
Holds cations and anions in ionic compounds
Dot and cross diagrams
Outer shell of electrons in metal are transferred to outer shell of non metals to achieve a full outer shell in order to be more stable
Negative and positive ions formed
Has the same structure as the nearest noble gas
Why does a giant ionic lattice form
Ions attract oppositely charged ions in all directions
Each ion is surrounded by 6 of the other ion
Properties of ionic lattices
Melting points - high
Solubility - in polar solvents
Electrical conductivity - liquid or aqueous solution
Melting points of ionic structures
Solid at room temperature - insufficient energy to overcome sting electrostatic forces of attraction between opposite charges
A lot of heat needed to overcome this attraction
When are melting points higher
Lattices with greater ionic charges
Size of ions - bigger they are , more attraction
Solubility
Ionic compounds dissolve in polar solvents
Polar water breaks down the lattice and surrounds each ion in solution
Lattices with ions of large charges are too strong for water to breakdown - are less soluble
Electrical conductivity
Solid
Ions are fixed
No mobile charge carriers
Melted / dissolved in water
Solid ionic lattice breaks down
Ions are free to move and carry a charge
Conductor
WHat is covalent bonding
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
The overlap of orbitals each containing 1 electron
Ions attract in all directions … what about covalent bonds
The attraction is localised
Solely between shared electrons and nuclei
Resulting in a molecules - h2 h2o
What is a molecule
The smallest part of a covalent compound that can exist whilst retaining the chemical properties of a compound
Displayed formula
Shows the relative positing of atoms and the bonds between them
