Formation of Ions

Formation of IonsFormation of Ions

Formation of IonsFormation of Ions

Elements tend to lose or gain Elements tend to lose or gain electrons to fill their outermost electrons to fill their outermost energy levels with eight electrons energy levels with eight electrons depending on their electron depending on their electron affinityaffinity

As a general rule, metals will give As a general rule, metals will give electrons away and nonmetals will electrons away and nonmetals will accept electrons.accept electrons.

fill their outermost energy levels fill their outermost energy levels with eight electrons:with eight electrons:

Attain Noble Gas StatusAttain Noble Gas Status

Sodium: 1sSodium: 1s22 2s 2s22 2p 2p66 3s 3s11

[Ne] 3s[Ne] 3s11

Chlorine: 1sChlorine: 1s22 2s 2s22 2p 2p66 3s 3s22 3P 3P55

[Ne] 3s[Ne] 3s22 3P 3P55

Formation of IonsFormation of Ions

This causes an imbalance of This causes an imbalance of charge (more or less electrons charge (more or less electrons than protons)than protons)

This imbalance in the element is This imbalance in the element is called “ionizing”, and the element called “ionizing”, and the element is transformed into an “ion”is transformed into an “ion”

Formation of IonsFormation of Ions

The charge of an ion can be The charge of an ion can be computed by subtracting the computed by subtracting the number of protons by the new number of protons by the new number of electrons:number of electrons: Chlorine would gain 1 electrons so: Chlorine would gain 1 electrons so:

17 - 18 = -1 charge17 - 18 = -1 charge

Formation of IonsFormation of Ions

Sodium would lose 1 electrons so: Sodium would lose 1 electrons so:

11 - 10 = +111 - 10 = +1

An ion and its charge is An ion and its charge is represented by the element's represented by the element's symbol and then the charge is symbol and then the charge is written after it as a superscript:written after it as a superscript:

Na+1 Cl-1

Formation of IonsFormation of Ions

The general term for a positive The general term for a positive ion is a ion is a cationcation..

The general term for a negative The general term for a negative ion is an ion is an anionanion..

Formation of IonsFormation of Ions

It may be easier to draw the It may be easier to draw the electron dot for the specific electron dot for the specific element and then see if the element and then see if the element will add or subtract element will add or subtract electrons to form eight electrons electrons to form eight electrons in its outermost shell. in its outermost shell.

Formation of IonsFormation of Ions

(four or more dots, add electrons; (four or more dots, add electrons; four or less dots, subtract four or less dots, subtract electrons.)electrons.)

LiSubtract one electron

Li+1

Formation of IonsFormation of Ions

Remembering the Periodic Law Remembering the Periodic Law will help you realize that all of the will help you realize that all of the elements in each column will have elements in each column will have the same charge as an ion:the same charge as an ion:

Formation of IonsFormation of Ions

• Na = NaNa = Na+1+1

• K = KK = K+1+1

• Li = LiLi = Li+1+1

• and so onand so on

Formation of IonsFormation of Ions

Unfortunately, since the transition Unfortunately, since the transition metals have only two electrons in metals have only two electrons in their outermost energy level, we their outermost energy level, we cannot use the Rule of Eight to cannot use the Rule of Eight to determine their ionic charge.determine their ionic charge.

Formation of IonsFormation of Ions

To accommodate this, we will To accommodate this, we will assume that an ion of a transition assume that an ion of a transition metal will be +2 unless otherwise metal will be +2 unless otherwise stated (they have the ability to stated (they have the ability to have more than one oxidation have more than one oxidation number).number).

Ionic ChargeIonic ChargeAssignmentAssignment

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Assignment