Mammoth Memory

Ions

Ions are created when a neutral atom loses or gains electrons.

Ions are created when atoms lose or gain electrons
To remind you, here’s an image of electronic robots (electrons) playing a round of golf using golf irons (ions).

An ion is an atom or molecule that carries an electric charge.

Ions are identified with the sign and size of their charge.

Negatively charged ions are called anions.

Positively charged ions are called cations.

Examples of anions:

Br ⁻ = Bromine atom which has gained an electron

N³⁻ = Nitrogen atom which has gained 3 electrons

Examples of cations:

Na⁺ = Sodium atom which has lost an electron

Fe³⁺ = Iron atom which has lost 3 electrons

Example 1

 

When sodium and chlorine react sodium looses an electron and chlorine gains it

When a sodium atom and chlorine atom meet, the sodium atom loses an electron and the chlorine atom gains the electron, to give:

 

When an atom looses or gains an electron it becomes an ion, metal ions are charged positively and non metals are charged negatively, therefore sodium will be a positive ion and chlorine a negative ion or chloride ion

Note: When chlorine gains an electron to become an ion, it is known as a chloride ion not a chlorine ion.

 

The sodium ion is said to be a one + ion or Na+ ion as it has lost one negatively charged electron.

When sodium lost an electron to a chlorine the ion becomes negatively charged electron therefore sodium becomes NA+

The chlorine atom becomes a one – ve chloride ion or Cl- as it has gained one negatively charged electron.

Chlorine gained a negatively charged particle from sodium it becomes Cl-

 

 

The positive and negative charges of these ions attract one another and this forms an ionic bond to make the compound sodium chloride or NaCl.

 

Example 2

 

Magnesium loses 2 electrons to oxygen

When a magnesium atom and oxygen atom meet, the magnesium atom loses two electrons and the oxygen atom gains the two electrons, to give:

 

When electrons have been passed the magnesium becomes Mg2+ and oxygen becomes an oxide ion O2-

Note: When oxygen gains electrons to become an ion, it is known as an oxide ion not an oxygen ion.

 

The magnesium is said to be a two + ion or Mg2+ ion as it has lost two negatively charged electrons.

 

Magnesium has lost 2 negatively charged particles therefore it is Mg2+

The oxygen atom becomes a two – ve oxide ion or O2- as it has gained two negatively charged electrons.

 

Oxygen becomes an oxide ion and has gained 2 negatively charged electrons so it is O2-

 

The positive and negative charges of these ions attract one another, forming an ionic bond to make the compound magnesium oxide or MgO.

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