{ Challenge 17

Which black rectangle is bigger?

IONIC BOND bond formed between a Metal and a Non Metal It is a transfer of electrons Metals- give up valence electrons Non –metals take in

Ionic Bonding

Ionic bonding is the combining of two or more ions to form an electrically-neutral compound How Ionic Bonding Works 1) The giving atom loses a valence electron (or 2 or 3) so that it has a full valence shell, but a positive charge 2) The gaining atom gains a valence electron (or 2 or 3) so that it has a full valence shell, but a negative charge

3) The negative and positively-charged ions are attracted to each other (like a magnet) based on their opposite charge

If you look at your periodic table, you will see that ionic bonding usually occurs in compounds formed between one metal and one nonmetal

Metals in Ionic Bonds In ionic bonds, metals are always the cation -- metals are on the left side of the periodic table and only have 1, 2, or 3 valence electrons -- it is very easy to lose these electrons and become positively charged

Nonmetals in Ionic Bonds Nonmetals (with the exception of hydrogen) are always the anion in ionic bonds -- nonmetals all have 4 or more valence electrons, so it is very easy for them to gain electrons to get a full valence shell -- when nonmetals gain electrons, they get a negative charge

Drawing Ionic Bonds When a nonmetal is exposed to a metal, the metal will lose electrons and the nonmetal will gain electrons, forming a new compound

-- that new compound is held together by an ionic bond The individual atoms will have a charge, but the overall compound will be neutral When we draw the compound, using Lewis Structures, we show the extra electron around the anion and the cation as having no valence electrons -- each ion in the compound is shown as being charged Example:

Na + Cl

Na Cl

Formation of Ions from Metals



Ionic compounds result when metals react with nonmetals



Metals lose electrons to match the number of valence electrons of their nearest noble gas



Positive ions form when the number of electrons are less than the number of protons

Group 1 metals  ion 1+ Group 2 metals  ion 2+ 

Group 13 metals  ion 3+

Formation of Sodium Ion

Sodium atom

Na  2-8-1 11 p+ 11 e0

– e

Sodium ion



Na +

2-8 ( = Ne) 11 p+ 10 e1+

Formation of Magnesium Ion

Magnesium atom 

Mg 

2-8-2 12 p+ 12 e0

– 2e

Magnesium ion



Mg2+

2-8 (=Ne) 12 p+ 10 e2+

Some Typical Ions with Positive Charges (Cations) Group 1

Group 2

Group 13

H+

Mg2+

Al3+

Li+

Ca2+

Na+

Sr2+

K+

Ba2+

Learning Check A. Number of valence electrons in aluminum 1) 1 e2) 2 e3) 3 eB.

C.

Change in electrons for octet 1) lose 3e2) gain 3 eIonic charge of aluminum 1) 32) 5-

3) gain 5 e-

3) 3+

Solution A. Number of valence electrons in aluminum 3) 3 eB.

Change in electrons for octet 1) lose 3e-

C.

Ionic charge of aluminum 3) 3+

Learning Check Give the ionic charge for each of the following: A. 12 p+ and 10 e1) 0 2) 2+ 3) 2B. 50p+ and 46 e1) 2+ 2) 4+

3) 4-

C. 15 p+ and 18e2) 3+ 2) 3-

3) 5-

Fluoride Ion unpaired electron 

:F





2-7

9 p+ 9 e0

+ e

: F:

octet  1 

2-8 (= Ne)

9 p+ 10 e1ionic charge

Ions from Nonmetal Ions In ionic compounds, nonmetals in 15, 16, and 17 gain electrons from metals

Nonmetal add electrons to achieve the octet arrangement

Nonmetal ionic charge: 3-, 2-, or 1-



 



Between atoms of metals and nonmetals with very different electronegativity Bond formed by transfer of electrons Produce charged ions all states. Conductors and have high melting point. Examples; NaCl, CaCl2, K2O

Ionic Bond

Diagram of Ionic Bonding

1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.

What happens in an ionic bond? • In an IONIC bond, electrons are given or taken, resulting in the formation of IONS. • The “bond” holds the atoms together and is a result of the negative and positive ions attracting to one another (opposites attract).

K

F

K F

K

F

K F

K F

K F

+

_

K F •The compound potassium fluoride consists of a potassium (K+) ion and a fluoride (F-) ion. •K is positive now because it gave an electron and F is more negative because it took the electron.