Introduction to Chemical Bonding Atoms seldom exist as

Introduction to Chemical Bonding Atoms seldom exist as independent particles in nature. Nearly all substances consists of combinations of atoms that are held together by chemical bonds. A chemical bond is a mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together.

Why are most atoms chemically bonded to each other? • Most atoms are less stable existing by themselves. By bonding with each other, atoms decrease their energy creating a more stable arrangement.

Octet Rule • Chemical Compounds tend to form so that each atom, by gaining, losing, or sharing electrons, has an octet of (8) valence electrons. • Each atom wants to achieve the same arrangement as the Noble Gases. • Which Noble Gas is stable with only 2 valence electrons?

Three Major Types of Chemical Bonding • 1. Ionic Bonding • 2. Covalent Bonding • 3. Metallic Bonding

IONIC BONDING When an atom of a metal gives one or more electrons to a non-metal so both atoms end up with 8 valence electrons

IONIC BOND FORMATION Neutral atoms come near each other. Electron(s) are transferred from the Metal atom to the Non-metal atom. They stick together because of electrostatic forces, like magnets.

IONIC BONDING IONS – any atom with more or less electrons than its Neutral atom. There are 2 Types of Ions: Cations – positively charged ions Anions – negatively charged ions

Positive Ions are formed when… Metals tend to lose electrons to become stable, and they are called……… CATIONS Normal sodium atom loses one electron to become sodium ion

Ionic Bond Video

Cations When sodium forms a compound with a non-metal - it is called a sodium ion. +1 It is written as Na , meaning that it loses one electron to become stable. The +1 symbol means it has lost one electron

The Sodium atom has 1 Electron in it’s outer shell. Na e. c. 2, 8, 1 Atom The Sodium loses 1 electron to leave a complete outer shell. It is now a Sodium ion with a charge of 1 + (Na +) e. c. (2, 8)+ Ion +

Mg+2 1. How many valence electrons does Mg have? 2. How many electrons does it need in its highest energy level to be stable? 3. What does the Mg atom do in order to become stable? (Achieve the same configuration as a Noble Gas? )

ANSWERS • 1) 12 • 2) 8 (octet rule) • 3) lose 2 electrons

Negative Ions Nonmetals will tend to gain electrons to become stable, and they are called ANIONS Normal chlorine atom gains an electron to become a chloride ion

The Chlorine atom has 7 electrons in it’s outer shell. Cl e. c. 2, 8, 7 Atom The Chlorine gains 1 electron to gain a complete outer shell. It is now a Chlorine ion with a charge of 1 - (Cl - ) e. c. (2, 8, 8)Ion

ANIONS 2 S is called a sulfide ion 2 symbol The means it gains two electrons to become stable

Classwork / Homework • Ionic Bonds Worksheet

There is another special group of anions, called Polyatomic Ions

Polyatomic Ions – Pg. 226 A group of atoms that act like one anion and carry a negative charge. 2) --carbonate (CO 3 ion 3(PO 4) -- phosphate ion

Polyatomic Ions -EXCEPTION • The one exception is NH 4 (ammonium), which is a cation and carries a positive charge. +1

Polyatomic Ions POLYATOMIC IONS ACT JUST LIKE ANY OTHER NEGATIVE ION WHEN BONDING Na and 2(SO 4) What is the metal? What is the non-metal? What charge does (SO 4) have ?

Name and give the charge of the following Polyatomic Ions • Ba (NO 3)-1 • Mg(PO 4)3 • Li(Cl. O)-1

ANSWERS • Barium nitrate • Magnesium phosphate • Lithium hypochlorite

Properties of Ionic Compounds 1. At room temperature, most ionic compounds are crystalline solids. 2. Ionic compounds are brittle, and shatter if they are hit. 3. Because of their strong electrostatic attractions, ionic compounds are very strong and have high boiling and melting points. 4. When melted or dissolved, ionic compounds conduct electricity.