5-1 Notes Part 1: Ionic Compounds Please have your Periodic Table out.

Compounds A compound is a pure substance that contains two or more different elements. CO 2 H 2 O HCl O 2

Compounds A chemical formula: –is an ingredient list for a compound to show which elements to use and how many of each –uses symbols and subscripts –shows the ratio of elements in a molecule

Compounds symbols – tell you which element(s) to use subscripts – tell you how many of each element to use H2O2H2O2 CO 2 symbol subscript

Compounds formulas of familiar compounds: CompoundFormula WaterH2OH2O Carbon DioxideCO 2 Carbon MonoxideCO MethaneCH 4 AmmoniaNH 3 Table SugarC 12 H 22 O 11

water vs. sucrose (sugar) H 2 O C 12 H 22 O 11 Compounds

Compounds and Elements Compounds have different properties than the properties of its individual elements.

Compounds and Elements For example: –The element Sodium (Na) is a soft metal and is explosive when added to water.

Compounds and Elements In fact… ALL the alkali metals (Group 1) are explosive when added to water.

Compounds and Elements Check it.

Compounds and Elements –The element Chlorine (Cl) is a greenish- yellow gas and is DEADLY by itself. The Iraqi army destroys what it says is an IED planted by ISIS containing chlorine gas in March 2015.

Compounds and Elements First used in World War I by the Germans in 1915:

Compounds and Elements –The compound Sodium Chloride (NaCl) is table salt and you need some (no more than 1 teaspoon a day) in your diet to help your nerves work properly.

Lewis Dot Diagrams The force that holds atoms together in a compound is called a chemical bond. caffeine

Lewis Dot Diagrams

The electrons in an atom’s outside energy level are called valence electrons.

Lewis Dot Diagrams

Valence electrons are the only ones involved in forming bonds. GROUP NUMBER VALENCE NUMBER

Lewis Dot Diagrams Lewis dot diagrams use symbols and dots to represent only the valence electrons. 1A 2A 3A 4A 5A 6A 7A 8A

Lewis Dot Diagrams

Ionic Compounds Overview An ionic compound: when atoms gain or lose electrons (forming ionic bonds).

Ionic Compounds Overview 1 electron leaves Na and goes to Cl. This makes Na+ and Cl-

Another casualty in the War of the Atoms

Ionic Compounds Overview An ionic bond is an electrical attraction between positive and negative ions. Na+ Cl-

Ionic Compounds Overview Atoms become charged by giving one or more electrons to another atom & both atoms become ions.

Ionic Compounds Overview The positive ion is usually a metal (left side) The negative ion is usually a non-metal (right side)

Ionic Compounds Overview Positive Ion or Negative Ion? 1.Magnesium 2.Nitrogen 3.Chlorine 4.Sodium 5.Helium Positive (2+) Negative (3-) Negative (1-) Positive (1+) NEITHER! does not form ions

Forming an Ionic Compound Example Lithium Lithium loses its 1 valence electron and becomes a positively charged ion (1+). Fluorine Fluorine gains the 1 valence electron and becomes a negatively charged ion (1-).

Forming an Ionic Compound Example The lithium ion (1+) and fluorine ion (1-) now have equal and opposite charges. They are attracted to each other and form a compound: Lithium fluoride (LiF).

Forming an Ionic Compound Example Lithium fluoride is in a category called binary compounds (made of just 2 elements)

Using the Periodic Table to Form Ionic Compounds Elements in the same column on the periodic table form a group (or family).

Atoms in Group 1A: –have 1 valence electron –if they get rid of it, their energy levels will all be maxed –so they give up 1 electron to form 1+ ions. 1+ Using the Periodic Table to Form Ionic Compounds

Atoms in Group 7A: –have 7 valence electrons –need 1 more electron to make 8 –so they take an extra electron to form 1- ions. 1- Using the Periodic Table to Form Ionic Compounds

When a positive ion from Group 1A and a negative ion from Group 7A combine, a salt such as sodium chloride (NaCl) forms. Using the Periodic Table to Form Ionic Compounds 1A + 7A = 8

Group 2A elements give up 2 electrons to form ions with a 2+ charge. Group 6A elements need 2 electrons and form ions with a 2- charge. All group 2A and group 6A elements are attracted to each other. Using the Periodic Table to Form Ionic Compounds 2A + 6A = 8

Ionic Compound Properties Usually solids at room temperature Brittle and break apart easily

Ionic Compound Properties Have high melting and boiling points H 2 O 0 100

Ionic Compound Properties If they dissolve in water they are good conductors of electricity (saltwater)

Noble Gases Elements in Group 8A are the Noble Gases. Noble gases are stable because their energy levels are maxed. Stable elements rarely react to form compounds.

End of 5-1: Ionic Compounds