Ionic Compounds NaCl Quartz

Many of the rocks and minerals on Earth are made of cations and anions…ionic compounds.

The most common mineral on Earth is quartz, silicon dioxide, SiO2. Most sand is made of quartz.

The second most abundant compound in Earth’s crust is aluminum oxide, Al2O3. Corundum is the second hardest mineral known, and it is composed of aluminum oxide, Al2O3. Pure corundum is clear.

Corundum is also one of the most valuable of the gem minerals. Red corundum contains minute amount of chromium Blue corundum contains minute amount of iron and titanium Red corundum is called ruby. Blue corundum is called sapphire.

Pyrite, or fool’s gold, is composed of iron sulfide, FeS2.

Although they are composed of ions, ionic compounds are electrically neutral. The total positive charge of the cations equals the total negative charge of the anions. Na+ Cl- Ex: NaCl (+1) + (-1) =

Water is a molecular compound; it consists of molecules. A glass of water would be filled with millions of molecules of water. H2O H2O H2O H2O H2O H2O H2O H2O H2O

Ionic compounds do not consists of molecules. Ionic compounds do not exist as single discrete units, but as collections of positively and negatively charged ions arranged in repeating patterns. Each ion is attracted to many oppositely charged ions. In NaCl, each Na+ is attracted to 6 Cl-, and each Cl- is attracted to 6 Na+.

Properties of Ionic Compounds Most ionic compounds are crystalline solids at room temperature. The ions in such crystals are arranged in repeating three-dimensional patterns. NaCl CsCl ZnS

 Ionic compounds are very hard and brittle. In an ionic compound, the ions are fixed in place and each ion forms ionic bonds with neighboring ions, resulting in a very strong structure. It takes a lot of energy to break apart the ionic bonds holding these ions together. If we give a large crystal a hard enough whack with a hammer, the crystal will break in various places, the crystal shatters.

 Ionic compounds have high melting points. In order to melt a substance, their particles must be able to move (flow). In an ionic compound, the ions are fixed in place and each ion forms ionic bonds with neighboring ions, resulting in a very strong structure.

 Ionic compounds have high melting points. In NaCl, each Na+ is ionically bonded to 6 Cl-, and each Cl- is ionically bonded to 6 Na. A large amount of energy is required to break all the ionic bonds holding these ions together. As a result, ionic compounds have high melting points.

Ionic compounds have high melting points. https://www.youtube.com/watch?v=E_q6OC1quSk

Ionic compounds have high melting points. Compound Name Formula Type of Compound Melting Point °C Boiling Point °C Magnesium fluoride MgF2 ionic 1261 2239 Sodium chloride NaCl 801 1413 Sucrose (sugar) C12H22O11 covalent 186   Water H2O 100 Hydrogen fluoride HF -83 20

Ionic compounds can conduct an electric current when melted or dissolve in water. Charged particles must be free to move for a material to conduct an electric current. In the solid state, ionic compounds do not conduct electricity because their ions are fixed in place. However, when ionic compounds are melted or dissolved in water, the ions are free to move. https://www.youtube.com/watch?v=ODbgKXFED5o