Grade 11 Chemistry - Chemical Compounds and Bonding

Chemical bond

The force of attraction between two atoms or ions

Electrolyte

A compound that dissolves in water, producing a solution that conducts electricity

Ionic compounds have several properties like

-They are hard and brittle

-They have relatively high melting and boiling points. For example, sodium chloride melts at 801 C

-They conduct electricity as molten liquids but not as solids

-They conduct electricity when dissolved in water

Ionic bond

The electrostatic force of attraction between a positive ion and a negative ion; a type of chemical bond

Formula unit

The smallest repeating unit in an ionic crystal

Ionic compound

A pure substance composed of positively charged ions and negatively charged ions in a fixed ratio

Ionic compounds have relatively high melting points because

Their ions are held together by strong electrostatic forces

Ionic compounds are hard because

Their bonds resist being stretched

A piece of sodium chloride is easily cracked or fractured because

When an outside force strikes the crystal, the crystal lattice structure is offset. Suddenly, positively charged ions are side by side with other positively charged ions. A repulsive force quickly develops between the like charges, and the crystal breaks

Ionic compounds are electrolytes because

when an ionic crystal is placed in water, water molecules surround each ion and separate it from the crystal. The crystal breaks up or dissolves, releasing free-floating ions into the solution. The ions are able to move, and thus to carry electric charges, through the water. This is what happens when electricity passes through a solution

Molecular element

A pure substance composed of molecules made up of two or more atoms of the same element

Diatomic

Made up of two atoms

Molecular compound

A pure substance composed of molecules made up of two or more non-metallic elements

Covalent bond

The bond that results from the sharing of a pair of electrons by two atoms

Bonding electron

An electron, or in the valence shell of an atom, that is available to form a covalent bond with another atom

Lewis structure

A representation of covalent bonding based on Lewis symbols; a model in which shared electron pairs are shown as lines and unshared electrons are shown as dots

Bonding capacity

The number of covalent bonds that an atom can form

Lone pair

A pair of electrons that is not involved in covalent bonding

Structural formula

A representation of the number, types and arrangement of atoms in a molecule, with dashes representing covalent bonds