Chem. warm-up: What is the difference between an ionic and covalent compounds? Ionic compounds are made of ions (Cations & Anions) and transfer electrons, whereas covalent compounds are made of two nonmetals and share electrons

Properties At room temperature they are a crystalline solid. Ionic Compounds: At room temperature they are a crystalline solid. Hard & Brittle, High melting point Covalent (Molecular Compounds): At room temperature they can be a solid, liquid or gas. Usually soft & low melting point

Compound Arrangement Three dimensional pattern Ionic Compound Three dimensional pattern How is the 3D pattern created? Oppositely charged ions form closely packed layers. Layers stack together to make a regular repeating 3D pattern called a: Unit cell Closely packed layers will keep stacking to form a: Crystal

Compound Arrangement Molecular Compound Consist of atoms (nonmetals) which form molecules that are held together by weak forces. Weak forces Water molecules

Type of Bond Force & Strength Ionic Compounds: Electrostatic forces Very Strong Covalent (Molecular Compounds): Intermolecular forces Weak The force of attraction between atoms in metals, such as copper and aluminum, or alloys, such as brass and bronze, are metallic bonds. Dispersion forces, Dipole-dipole, H-bonding Strength

Good conductors of electricity Ionic Compounds: Good conductors of electricity Two ways ionic compounds conduct electricity: Conduct an electric current in the melted state. Conduct electricity when the compound is dissolved in water. Conductors

The ion movement produces a flow of electricity Conductors Ionic Compounds cont… How? Bonds break or dissociate. The ions separate. Ions are free to move around. The ion movement produces a flow of electricity When a voltage is applied the cations move to one electrode & the anions to the other.

Conductors Poor conductors Why? Molecular Compounds: Bonds do not break easily. Compound does not easily dissolve in water. Compound does not contain ions that can conduct electricity.

Network Solids +Network Solid Consist of atoms held together by large chains of covalent bonds. Each atom is covalently bonded in a large chain or network. There are NO molecules in a network solid, only atoms bonded together. Covalent solids, such as diamond, form crystals that can be viewed as a single giant molecule made up of an almost endless number of covalent bonds. Each carbon atom in diamond is covalently bound to four other carbon atoms oriented toward the corners of a tetrahedron, as shown in the figure below. Because all of the bonds in this structure are equally strong, covalent solids are often very hard and they are notoriously difficult to melt. Diamond is the hardest natural substance and it melts at 3550°C Bonds are very strong. Example: Diamond +Network Solid

Reading Quiz 1 Write the title on your paper. The attraction between an anion & a cation forms an _________ bond. List the three types of compounds found in chapter 15. 3. List the type of compound that conducts electricity when dissolved in water. 4. List the type of compound or solid that only contains one type of atom & is the simplest crystalline solid. 5. An __________ is a compound that contains a mixture of 2 or more metals. Pass your paper forward