Grade 8 Integrated Science Chapter 8 Lesson 3 on ionic and metallic bonds. An introduction to electron pooling, conductors, and ions.

1. Chapter 8 Lesson 3: Ionic and Metallic Bonds – p 283-289 – page 1
Vocabulary
• Ion (284) – an atom that is no longer electrically neutral because it has lost or gained valence
electrons
• Ionic bond (286) – the attraction between positively and negatively charged ions in an ionic
compound
• Metallic bond (287) – a bond formed when many metal atoms share their pooled valence
electrons
Understanding Ions
•
•
When a metal and non-metal bond, they do not ____________ electrons
Instead, one or more valence electrons _____________ from the metal atom to the
nonmetal atom
•
After electron transfer, the atoms bond and form a chemically stable compound
• When an atom loses or gains a valence electron, it becomes an_____________.
• An ion is an atom that is no longer electrically neutral because it has lost or gained valence
electrons
• Because electrons have a negative charge, losing or gaining an electron changes the overall
________________ of an atom
• An atom that loses valence electrons becomes an ion with a
______________ charge
– Because the number of electrons is now less than the number of
protons
• An atom that gains an electron becomes an ion with a
________________ charge
– Because the number of protons is now less than the number
electrons

2. Chapter 8 Lesson 3: Ionic and Metallic Bonds – p 283-289 – page 2
Losing Valence Electrons
• Look at Sodium
– Sodium is a metal
– It has an atomic number of _______
• That means 11 protons and 11 electrons
– It is in group 1
• That means it has ____ valence electron
– Therefore, it is _______________
• Metal atoms, such as sodium, become more stable when they lose valence electrons and
form a chemical bond with a nonmetal
• If sodium loses one electron it will have a total of __________ electrons, __________ of
them being valence electrons
– That means it would have the electron configuration of a noble gas.
– It would be chemically ____________________.
Gaining Valence Electrons
•
•
Nonmetal atoms can also _________ valence electrons with metal atoms
•
•
If a chlorine atom can gain one electron, it will have ______ valence electrons
Look at chlorine
– Chlorine has an atomic number of ___________
• That means 17 protons and 17 electrons
– Its in group 17
• That means __________ valence electrons
– It is chemically unstable
Then, it will have the electron configuration of the noble gas ____________ (Ar).

3. Chapter 8 Lesson 3: Ionic and Metallic Bonds – p 283-289 – page 3
•
When sodium loses a valence electron, it becomes a _______________ charged ion.
– This is shown by a plus sign (+)
•
When a chlorine atom gains a valence electron, it becomes a ______________ charged ion.
– This is shown by a negative sign (-)
Determining an Ion’s Charge
• Once an atom gains or loses electrons, it becomes a charged ion.
• For example:
– Nitrogen has 7 electrons and 7 protons
– However, if N gains 3 electrons when forming an ion, the N ion then has 10 electrons
• To determine the charge, _______________the number of electrons in the ion from the
number of protons.
7 protons – 10 electrons = -3 charge
– So, it is a N ion with a -3 charge, shown as N^3Ionic Bonds – Electron Transferring
•
Metal atoms typically lose valence electrons and __________________ atom typically gain
valence electrons
•
In an ionic bond, the nonmetal atom _____________ the electrons that the metal atom loses
• In NaCl
– Na loses ___________ valence electron
• Na becomes a positively charged ion
– Cl gains that _________ electron
• Cl becomes a negatively charged ion
– These ions attract each other and form a stable ionic compound.
• The _________________________between positively and negatively charged ions in an ionic
compound is an ionic bond.
Ionic Compounds
•
•
Usually solid and __________ at room temperature
Relatively ___________ melting and boiling points

4. Chapter 8 Lesson 3: Ionic and Metallic Bonds – p 283-289 – page 4
•
•
Many ionic compounds ___________ in water
Water that contains ionic compounds is a good conductor of electricity.
– This is because the electrical charge can pass from ion to ion in the solution
Comparing Ionic and Covalent Compounds
•
When nonmetal ions bond to metal ions in an ionic compound, there
are no molecules.
•
•
Instead, there is a large collection of ______________charge ions.
All of the ions attract each other and are held together by ionic
bonds
Metallic Bonds – Electron Pooling
•
Metal atoms form compounds with one another by_______________ , or pooling, their
valence electrons
•
A ________________ bond is a bond formed when many metal atoms share their pooled
valence electrons
•
•
•
•
In metallic bonds, metal ions lose their valence electrons and become positive ions.
The electrons move from ion to ion.
Valence electrons in metals are not bonded to one atom.
Instead, a “______________________________________” surrounds the positive ion
Properties of Metallic Compounds
• Metals are good conductors of _____________________ energy and electricity
• Because the valence electrons can _______________ from ion to ion, they can easily
conduct electric current.
• Metal ions can slide past one another in the electron sea and move into new positions.
• Metals are __________________because the valence electrons at the surface of the metal
interact with light

5. Chapter 8 Lesson 3: Ionic and Metallic Bonds – p 283-289 – page 5

6. Chapter 8 Lesson 3: Ionic and Metallic Bonds – p 283-289 – page 6