Valence Electrons and Ionic Bonds

Ionic Bonds

Atoms form ionic bonds by transferring electrons.

Recall:

• Atoms want to have a full outermost shell (stable).

• In order to do this, they either gain/lose their valence electrons or they share them.

• Ionic bonds form between metals + nonmetals.

Octet Rule

• All atoms are trying to achieve a stable octet.

• This means they want to have a FULL outermost shell with 8 electrons (remember Helium has only 2).

• Atoms are stable, or resistant to change, if their outermost shell is full.

Multiple Choice

How many valence electrons do atoms want to have in order to be stable?

• 3

• 1

• 8

• 4

Valence electrons

• Atoms of ALL elements have 1 to 7 valence electrons EXCEPT for your noble gases.

Ions

• Atoms gain or lose electrons to meet stability.

• An atom that has gained or lost an electron is called an ion.

Multiple Choice

An atom that has gained or lost an electron is called a(n) _____.

• ion

• particle

• atom

Types of Bonds

• Ionic (metal + nonmetal)

• Covalent (nonmetal + nonmetal)

• Metallic (metal + metal) -- (we're not going to talk about this one)

Ions

• An ion is a charged particle that has either more or less electrons than protons.

Multiple Choice

An ion is a charged particle that has more or less ______ than _____.

• electrons than protons.

• protons than electrons

• electrons than neutrons

Ions

• When atoms LOSE electrons, it becomes POSITIVELY charged (called a cation).

• When atoms GAIN electrons, it becomes NEGATIVELY charged (called an anion).

• Some of the most common compounds are made by the loss/gain of ONE electron (between Group 1 and Group 17).

Multiple Choice

When ions LOSE electrons they become ____ charged.

• positively

• negatively

• same

Multiple Choice

When ions GAIN electrons, they become _____ charged.

• postively

• negatively

• same

Transfer of electrons

• Atoms are no longer neutral when they gain or lose electrons.

• Example: Potassium (K) and Iodine (I)

• Show the charge by using a superscript.

• Metals will lose their electrons while the nonmetals will gain them.

Zero net charge

• Atoms have a charge when they gain/lose electrons.

• HOWEVER, the compound as a whole is neutral because the sum of charges on the ions is zero.

• 
  

Ionic Bond

• When ions combine in this way (gain/lose electrons), an ionic bond is formed.

• Between a metal and a nonmetal.

• Typically on opposite sides of the Periodic Table.

Open Ended

How does Sodium (Na) and Chlorine (Cl) achieve a stable outer electron energy level when they form NaCl?

What kind of bond do they form?

Open Ended

Explain how an ionic bond is formed.