Properties of Solids

1. Properties of Solids

2. Physical properties • While solid has definite shape and volume; it does have various other properties that can be very different. Such as density, colour, melting points, etc Pg. 119

3. Ionic solids • Lots found in nature as rock and mineral deposits: • Sodium chloride (salt) • Potassium chloride (potash) • Also found at home: • Household cleaners (contains sodium hydroixde) • Other examples: • Rust (iron (III) hydroxide) • Tarnish (silver sulfide)

4. Cont’d • Some reactive metals don’t occur in elemental form in nature, they are found as ionic compounds • Ionic compounds are also used to extract metals from naturally occurring compounds • For example: iron is the most common metal used but is also very reactive

5. Formation • Formation reaction of a metal and nonmetal similar to sodium chloride • Formation reaction of two compounds • Ionic compound stability is similar to that of noble gases so it can be suggested that there is a total electron transfer occurring.

6. A model • At SATP, all ionic compounds are solid so they must be held together (bonded) in that rigid structure. • Models show that the ions are arranged in a regular pattern, depending on the size, shapes and charges • This is called a crystal lattice

8. Ionic Compounds • Ionic compounds are brittle – the ions don’t rearrange • Binary ionic compounds also have medium to high boiling points • Polyatomic ions have more complex crystal lattices but the ions have covalent bonds so can be treated like an monatomic ion

9. Metallic Crystals • Shiny, silvery, flexible solids with good electrical and thermal conductivity • Hardness varies greatly as well as the melting temperature • X-Ray diffraction shows that all metals have a continuous and compact crystalline structure

10. Metal Properties • Metallic bonding – continuous electron clouds • Low electronegativity – loosely holding electrons • Empty valence orbitals explains electron mobility • Strong Electrostatic attraction for bonding • this gives the many different properties to metallic compounds Pg. 124

11. Molecular crystal • Elements or compounds • Small molecules for solid crystal, low melting point, not very hard, nonconductors • Properties can be explained by the IMF and structure

12. Covalent Network Crystals • Crystal substances • Diamond and quartz – very hard • Very hard, high melting point, brittle, insoluble, nonconductors • Examples – silicon carbide SiC(s) used in sandpaper,

13. Carbon • Carbon is extremely versatile with bonding in various ways

14. Semiconductors • Crystalline silicon or germanium ‘doped’ with a Group 13 or 15 element • Little bit of energy to put an electron into a higher orbital and conduct electricity • Used in transistors, solar cells

15. Summary

17. Unit Test Review Summary • Lewis Formulas • Bonding Theory (types) • Electronegativity • Molecular Formulas (Lewis, structural, sterochemical) • Bonding capacity • VSEPR • Bond and molecular Polarity • Intermolecular Forces • Isoelectronic Compounds • Boiling points • Properties of Liquids and Solids

18. Suggested review questions • Pg. 137 #3, 6, 7, 10, 12, 14 • Pg. 138 #21, 25, 28 • Pg. 139 #35, 40, 41, 43 • Pg. 140 #48, 53, 57 • Pg. 141 #60