Chapter 5

Energy levels Energy increases as shells increase Shell number = principal quantum number

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

One sphere Greater the shell number, the greater the radius of the sphere

Dumbbell shape 3 orbitals at right angles to each other X y z Each shell from n = 2 has 3 p orbitals

N=3 5 orbitals

N=4 7 orbitals

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

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

Fill up each orbital before pairing

Uses Nobel gas (He)2s1

S - 2 groups P - last 6 groups D - transition metals F - below

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

The electrostatic attraction between positive and negative ions Holds cations and anions in ionic compounds

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

Ions attract oppositely charged ions in all directions Each ion is surrounded by 6 of the other ion

Melting points - high Solubility - in polar solvents Electrical conductivity - liquid or aqueous solution

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

Lattices with greater ionic charges Size of ions - bigger they are , more attraction

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

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

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

The attraction is localised Solely between shared electrons and nuclei Resulting in a molecules - h2 h2o

The smallest part of a covalent compound that can exist whilst retaining the chemical properties of a compound

Shows the relative positing of atoms and the bonds between them