Properties of compounds depending on the chemical bond Remember, 3 types of chemical bond: Ionic bond Between a metal and a non metal. The metal gives electrones to the non metal. A crystal is formed. Covalent bond Between non metals. Non metals share pairs of electrons. Some covalent compounds form molecules and other form crystals. Metallic bond Between metals. Metals lose electrons that travel through all the metal. All the lost electrons form an electron sea.

Properties of ionic compounds They are solids at room temperature and they have high melting points (because ionic bond is an strong bond and it is difficult to break). They can dissolve in water (think of table salt). When they melt or when they are dissolved in water they can conduct electricity, but they can´t conduct electricity when they are in a solid state (because in order to conduct electricity we need charges with the ability to move and in solid state the cations and anions are in fixed positions but in liquid state or dissolved they can move freely).

Properties of ionic compounds They are hard but fragile (when you hit the crystal, ions are displaced: positive charges face positive charges and negative charges face negative charges. Ions with the same charge repel each other. That´s why the crystal breaks even when it´s hit by small forces).

Properties of ionic compounds

Properties of covalent compounds or elements which form molecules They are gases at room temperature, or liquids with a low boiling point, or solids with a low melting point (because the forces between molecules are usually small). Some of them can dissolve in water but others can´t and dissolve in organic solvents, such as oil. They can´t conduct electricity (because there are no charges with the ability to move). They don´t conduct heat.

Properties of covalent compounds or elements which form crystals At room temperature they are solids with a high melting point (because the covalent bond is a strong bond and it is difficult to break it). They can´t dissolve in any solvent. They conduct neither electricity nor heat.

Properties of metallic elements At room temperature they are solids, except mercury, which is a liquid. They can dissolve in other metals, forming alloys (aleaciones). They can conduct electricity (because there are charges with the ability to move, the electrons of the electron sea).. They can conduct heat.