Chemical Bonding

Chapter 12

ObjectivesO SPI 0807.9.2 Identify the common outcome of

all chemical changesO SPI 0807.9.9 Use the periodic table to

determine the properties of an element.O I can:

1. Describe how atoms bond to form compounds. 2. Identify the number of valence electrons in an

atom.3. Draw electron dot diagrams for atoms to show

how valence electrons form bonds.

Chemical BondingO Joining of atoms to form new substances

O Formed by chemical changesO Form moleculesO Properties of the new substances are different

from the properties of the original elementsO Atoms are held together by an interaction

called a chemical bondO Formed when electrons are shared, gained, or

lost1. Ionic2. Covalent3. Metallic

I can describe how atoms bond to form compounds.

Chemical BondingO Valence electrons – electrons in the

outermost energy level in an atomO Form bonds

O Group number on the PT gives the number of valence electrons for each atomO Group 1: 1 valence electronO Group 2: 2 valence electronsO Group 3-12: 1 or 2 VEO Group 13: 3 VEO Group 14: 4 VEO Group 15: 5 VEO Group 16: 6 VEO Group 17: 7 VEO Group 18: 8 VE (He had 2 VE)I can identify the number of valence electrons in

an atom.

I can identify the number of valence electrons in an atom.

BondingO Atoms want 8 electrons in their

outermost energy levelO Atoms with less than 8 VE will more

likely form bonds

I can describe how atoms bond to form compounds.

How many valence electrons?

1. Sulfur O 6

2. MagnesiumO 2

3. HeliumO 2

I can identify the number of valence electrons in an atom.

Electron-dot DiagramsO Model that shows only valence

electrons in an atom1. Write chemical symbol for atom.2. Place 1 dot around symbol for every

valence electron.3. Place first 4 dots alone.4. Pair up remaining electrons with

dots.

I can draw electron dot diagrams for atoms to show how valence electrons form bonds.

I can draw electron dot diagrams for atoms to show how valence electrons form bonds.

Draw electron-dot diagrams

1. Sodium2. Phosphorous3. Aluminum4. Carbon5. Chlorine6. Calcium7. Argon

I can draw electron dot diagrams for atoms to show how valence electrons form bonds.

ObjectivesO SPI 0807.9.2 Identify the common outcome of

all chemical changesO SPI 0807.9.9 Use the periodic table to

determine the properties of an element.O I can:1. Explain how ionic bonds form.2. Explain how atoms become positively charged.3. Explain how atoms become negatively

charged.4. Distinguish between ionic, covalent, and

metallic bonds.

Ionic BondsO Bond that forms when electrons are

transferred from one atom to anotherO One or more valence electrons are transferredO Form by chemical changes

O Molecules bonded by ionic bonds tend to have high melting and boiling points, conduct electric current, and soluble

O Forms when a metal bonds with a nonmetalO Na + ClO Mg + OO K + ClI can explain how ionic bonds form.

I can distinguish between ionic, covalent, and metallic bonds.

IonO Charged particles

O Gain or lose electronsO Protons NEVER change for an atom

I can explain how ionic bonds form.

Forming Positive IonsO One atom loses electrons creating a

positive ion.O Atom has more protons than electronsO Metals lose electronsO Energy is needed to lose electrons

O Examples:O Na+

O K+

O Mg2+

O Al3+

O Ca2+

I can explain how atoms become positively charged.

Forming Negative IonsO One atom gains an electron creating a

negative ionO Atom has more electrons than protonsO Nonmetals gain electronsO Energy is given off to gain electrons

O The name changes when negative ions formO Change the ending of the name to –ide

O ExamplesO Chloride Ion: Cl-

O Oxide Ion: O2-

O Sulfide Ion: S2-

I can explain how atoms become negatively charged.

I can explain how ionic bonds form.

ObjectivesO SPI 0807.9.2 Identify the common outcome

of all chemical changesO SPI 0807.9.9 Use the periodic table to

determine the properties of an element.O I can:1. Explain how covalent bonds form.2. Identify which atoms will form covalent

bonds.3. Explain how metallic bonds form.4. Distinguish between ionic, covalent, and

metallic bonds.

Covalent BondO Bond that forms when electrons are shared

between atomsO Form by chemical changes

O Molecules that are covalently bonded tend to have low melting and boiling points: why they are mostly gases. Solids are brittle. They do not conduct electric current and are not soluble.

O Forms when a nonmetal bonds with another nonmetalO H + O → H2O

O C + O → CO2

O N + H → NH3I can explain how covalent bonds form.I can distinguish between ionic, covalent, and metallic bonds

The Simplest Molecules

O Two or more atoms joined together in a definite ratio

O Diatomic molecules – molecules made up of 2 atomsO Hydrogen (H2)

O Oxygen (O2)

O Nitrogen (N2)

O Fluorine (F2)

O Chlorine (Cl2)

O Bromine (Br2)

O Iodine (I2)I can identify which atoms will form covalent bonds.

I can identify which atoms will form covalent bonds.

I can identify which atoms will form covalent bonds.

More-Complex MoleculesWater Methan

e

Glucose Acetaminophen

I can identify which atoms will form covalent bonds.

Metallic BondsO Bond formed by the attraction between

positively charged metal ions and the electrons in the metal.O Metal ions form when metal atoms lose electronsO Outer most energy levels overlap allowing

valence electrons to move freely throughout the metal

O Allows metals to be reshapedO Malleability and ductility

O Allows metals to be bent without breakingO Electrons are able to move around when metal is

bentI can explain how metallic bonds form.I can distinguish between ionic, covalent, and metallic bonds.

I can explain how metallic bonds form.