Chemistry grade 10

Electron arrangement

Chemical compounds are represented using chemical names and chemical formulas.

• To tell different compounds apart, each one is given a unique chemical name.

• Each chemical name can be translated into a chemical formula. A chemical formula is a group

of letters and subscript numbers that represent the make-up of a chemical compound.

The letters in the compound are the chemical symbols of the elements in the compound.

• The subscript numbers tell you how many atoms of these elements are in the compound.

• Reactive elements can become more stable when they form compounds.

Sodium + Chlorine becomes sodium chloride

Compounds

• When elements form compounds, they become more stable because when the elements combine to form compounds, each element makes a full outer electron shell.

• Metal elements lose electrons to form positive ions to become more stable.

• Non-metal elements can gain electrons to form negative ions OR non-metals can share electrons to become more stable.

• Ions are atoms that have either a positive electrical charge or a negative electrical charge.

Binary Ionic compound

• A compound consists of a metal cation and non-metal anion.

• First part of the name always identifies the cation – usually a metal

• Second part of the name identifies the anion. Ends in the suffix “ide”

Name Symbol

Fluoride F-

Chloride Cl-

Oxide O2-

Sulfide S2-

Nitride N3-

Phosphide P3-

Elements in Ionic compound Name of Ionic compoundMagnesium and phosphorus Magnesium phosphideSodium and chlorine Sodium chlorideCalcium and bromine Calcium bromideAluminum and oxygen Aluminum oxide