Ionic Compounds Ionic Compounds (SALTS) formed by transferring electrons (giving/taking) occurs between a metal and a non-metal have an electro negativity difference greater than 1.7 unit is called "formula unit“ Since electrons are transferred, not shared, the atoms aren’t attached to each other like in a molecule exist as solids, usually crystalline have high melting points This is because of the strength of their bond. A stronger bond requires more energy to break soluble in water conducts electricity in water fixed + and – parts (anions & cations ) EXAMPLES: KCl, NaF, KNO 3

Crystalline Structure of Ionic Compounds

Metallic Bonds A metallic bond is a bond formed by the attraction between neighboring metal nuclei and the electrons around them. metal atoms create a crystal lattice of positive metallic nuclei in a 'sea of electrons'. Electricity is the movement of electrons Metals are good at conducting electricity because their bonds allow the electrons to flow freely because they are delocalized This means that they do not belong to any one atom but move freely about the metal’s network of empty atomic orbitals.

Metallic Bond Properties Electrical & thermal conductivity as a solid or liquid This is because of how freely the electrons can move High melting and boiling points This is because of the strength of their bond. A stronger bond requires more energy to break Malleable (sheets) and ductile (wires) The delocalized electrons in the 'sea' of electrons in the metallic bond, enable the metal atoms to roll over each other when a stress is applied. Shiny appearance Photons of light do not penetrate very far into the surface of a metal and reflect off the metallic surface.

Covalent Compounds formed by sharing electrons occurs between non-metals unit is called "molecule“ exists as liquids, gases, or non-crystal solids have low melting points This is because a covalent bond isn’t as strong as the other two types of bonds insoluble in water This is because covalent compounds to not have much of a difference in charge conducts electricity in water may have slightly + and - parts or totally neutral When they have a slight difference in charge, they are considered polar When there is no difference in charge, they are considered non-polar EXAMPLES: NH 3, CO 2, CH 4

Polar vs. Non-Polar Covalent Compound Polar Bonds Bonds in which atoms share electrons unequally are called polar covalent bonds. The electronegativity difference between the two atoms is between 0.5 and 1.7 Non-Polar Bonds Bonds in which atoms share electrons equally are called non-polar covalent bonds The electronegativity difference between the two atoms is below 0.5

Ionic, Metallic, Polar Covalent or non-polar covalent? Step 1: Figure out what type of element each atom is in the compound (metal or non-metal) Metal + Metal = Metallic Metal + Non-metal = Ionic Non-metal + Non-metal = Covalent (polar or non- polar) Step 2: If it’s a covalent compound, you must find the difference in negativity to determine if it is polar or non- polar by looking that the chart Non-polar molecules have an electronegativity difference of less than 0.5 Polar molecules have an electronegativity difference of greater than 0.5 but smaller than 1.7

Single, Double and Triple Covalent Bonds Single bonds Only 1 electron pair is shared (total of 2 electrons) Requires the least amount of energy to break Has the largest distance between nuclei of the 3 bonds Double bonds 2 electron pairs are shared (total of 4 electrons) Requires a moderate amount of energy to break Has a medium distance between nuclei of the 3 bonds Triple bonds 3 electron pairs are shared Requires the most amount of energy to break Has the shortest distance between nuclei of the 3 bonds

Single, Double and Triple Covalent Bonds

How do I figure out if it’s a single double or triple bond? ANS: Create a Lewis dot structure! Organic Chemistry Example: compare the carbon- carbon bond of the following compounds: 1. Ethane (C 2 H 6 ) 2. Ethene (C 2 H 4 ) 3. Ethyne (C 2 H 2 ) Which one has a single bond? Double bond? Triple Bond?