Chemical Bonding

Chapter 5

Compound

is a substance is made up of two or more different elements combined together chemically

Octet rule

when bonding occurs, atoms tend to reach an electron arrangement with eight electrons in the outermost energy level

Ion

is a charged atom or group of atoms

Cations

are positive ions

Anions

is negative ions

Ionic bond

is the force of attraction between oppositely charged ions

Crystal lattice

is the three-dimensional arrangement of ions

Valency

is the number of atoms of hydrogen which the element will combine with

Sigma bond

is formed by the head-on overlap of atomic orbitals

Pi bond 

is formed by the sideways overlap of p orbitals

Properties of Ionic bonds

• Contain a network of ions in he crystal

• Usually hard & brittle

• High melting & boiling points

• Usually solid at room temperature

• Conduct electricity when molten or dissolved in water

Properties of Covalent bonds

• Contain individual molecules

• Usually soft

• Low melting & boiling point

• Usually liquids, gases or soft solids at room temperature

• Don’t conduct electricity

Electronegativity

is the relative attraction that an atom in a molecule has for the shared pair of electrons in a covalent bond

Non-polar covalent

the atom in the molecule all share electrons equally

Polar covalent

is the atoms in the molecule don’t share the electrons equally

Intramolecular bonding

is bonding that takes place within a molecule

Intermolecular Forces

are the forces of attraction that exist between molecules

Van der Waals Force

forces gets stronger for bigger molecule. This is because bigger molecule have more electrons and therefore have a bigger chance of making a temporary dipole

Dipole-Dipole Forces

are forces of attraction between the negative pole of one polar molecule and the positive pole of another polar molecule 

Hydrogen Bonds

are particular types of dipole-dipole attractions between molecules in which Hydrogen atoms are bonded to Nitrogen, Oxygen or Fluorine