Properties of Compounds

What’s an Ionic (crystal) Lattice?

Millions of ions are packed together in a regular cubic

arrangement, joined by ionic bonds.

What happens when an Ionic (crystal) lattice is hit?

It’s brittle, so it shatters.

Ionic bonds are…

Ionic bonds are strong and a lot of heat is needed to break them.

Can ions in the solid state or liquid (molten), state conduct electricity?

Liquid (molten) ions as ions in molten state can move and conduct electricity.

What are the characteristics of covalent compounds?

• Some are liquids or gases at room temperature

• Others are solids and soft and malleable

• Some are nonpolar - Insoluble in water, soluble in organic solvents

• Others are polar-Soluble in water

• Low melting and boiling points:

  attraction between molecules is

  weak (intermolecular forces)

• Are not conductors of electricity/heat

What are metals and alloys?

Closely packed cations floating in a “sea of electrons” (delocalized).

• All the atoms are surrounded electrons.

• The electrons are not bound to

• individual atoms.

What are the properties of metals?

• Good conductors of electricity and heat

• Hugh luster: e- absorbs energy (excited/ground state)

• Very malleable and ductile: Free flowing electrons slip between the stationary cations.

• High melting and boiling points

• High densities

Why do certain metals conduct larger currents than others?

Some metals contain more free electrons per cubic meter than others.

What is corrosion?

It is the gradual destruction of a metal due to reactions with other chemicals in its environment. Over time, it can change the appearance of the metal.

Why doesn’t aluminum corrode?

The outer aluminum atoms react with oxygen in the atmosphere. This forms a thin layer of aluminum oxide on the metal’s surface, which protects the metal from corrosion.

What is rusting?

It is the specific name given to the corrosion of iron. It is a chemical reaction between iron, oxygen and water.

What can salt do to rusting?

Can increase the rate at which it occurs. This iron bolt is on a seaside structure and is nearly completely corroded.

What is an alloy

A metal composed of more than one element.

Most metals aren’t very strong in…?

Their pure form

Stainless steel is an alloy of…?

Iron and Chromium

What was the first alloy made?

Bronze, it is an alloy of copper and tin.

Brass is an alloy of…?

Copper and Zinc

Steel is an alloy of…?

Iron and Carbon

How hard steel is depends on…?

How much carbon is inside. Chromium is commonly added to steel to increase corrosion resistance and oxidation resistance.

Sterling Silver is an alloy of..?

Silver and Copper

What are alloy’s medical applications?

Nitinol (Ni and Ti) can be designed to apply constant force or stress over a variety of shapes. Alloys with memory form.

Metal alloy implants

Bone screws and plates made of surgical steel + titanium alloys.