Ms. Claudia Barahona

Types of chemical bonds: Ionic, Nonpolar covalent and polar covalent

Electronegativity Polarity Electron configuration and formation of ions Properties of ionic and molecular compounds Chemical bond and electrical conductivity Modern materials

Identifies key ideas in a text or speech and infers conclusions from them.

Communicates in a second language in daily life situations. Handles information and communication technologies to

obtain information. Identifies the systems and rules or core principles that lead to

a series of phenomena. Base opinions on science and technology impact of in our

daily life assuming ethical considerations.

The force that holds atoms or ions together in a compound.

A chemical bond can form by attraction between the

positive nucleus of one atom and the negative electrons of another atom, or by the attraction between positive and negative ions.

Introduction

All atoms want to satisfy the octet rule to be stable like noble gases.

Energy is released when bonds are formed, exothermic process.

1. What is a chemical bond? Ans// The force that holds atoms or ions together in a

compound. 2. Why do elements combine? Ans// Elements tends to gain or lose electrons, so they will

have the same number of electrons as a noble gas, to become more stable.

3. Do characteristics of the atoms change when they form a bond?

Ans// No, the atom is still the same. But even though the compound does not inherit the

properties of its parent elements, nevertheless their properties do determine the type of chemical bonding involved, which in turn largely determines the properties of the compound.

4. Choose a common binary compound you know, indicate its formula, mention 2 properties of the individual elements involved and mention two properties of the compound these elements can form.

Compound name: Sodium chloride Compound formula: NaCl Properties of the 1st element in the formula: Sodium – Na: 1. Soft lustrous metal 2. So reactive that it tarnishes immediately when exposed to air

and reacts explosively with water.

4. Choose a common binary compound you know, indicate its formula, mention 2 properties of the individual elements involved and mention two properties of the compound these elements can form.

Compound name: Sodium chloride Compound formula: NaCl Properties of the 2nd element in the formula: Chlorine - Cl2 1. Greenish yellow gas 2.Very corrosive and poisonous.

4. Choose a common binary compound you know, indicate its formula, mention 2 properties of the individual elements involved and mention two properties of the compound these elements can form.

Compound name: Sodium chloride Compound formula: NaCl Properties of the compound: sodium chloride, NaCl or table

salt: 1. Is a hard, brittle, high-melting, nonvolatile, transparent

crystalline solid that is nontoxic, dissolves quietly in water, and is unreactive toward most other substances.

5. What do you need for a bond to occur? Ans// Loosing, gaining or sharing of electrons.

6. Which are the types of bonds you have heard of? Ans// Ionic, Polar covalent, Nonpolar covalent, metallic

bond.

Octet rule: Tendency for atoms to attain a noble gas electron configuration.

7. How many electrons are needed to satisfy the Octet Rule? Ans// 8 electrons in the outer shell. 7. What does the phrase "has the same electron configuration of

a noble gas" mean? Ans// It indicates the acquisition of eight electrons in the

outer shell just as the noble gases naturally has.

9. What do the dots, in the Lewis structures represent? Ans// Represent the valence electrons. 9. What are the valence electrons? Ans// Electrons in the outermost shell of the atom.

Octet rule: Tendency for atoms to attain a noble gas electron configuration.

Compounds are the result of the formation of chemical bonds between 2 or more different elements,

Ionic Bonds: Metal atoms lose valence e- and atoms of nonmetals gain valence e-.

Bond that occurs when one or more electrons are transferred from the atoms of metals to atoms of nonmetals

Consist of positive and negative ions. Ions are held together by strong electrical attractions between the opposite charges called ionic bonds.

High melting points. Typically, crystalline solid at room temperature Good electrolytes (Conduct electricity when dissolve in

water).

• Covalent Bonds: Forms when atoms of nonmetals share valence e-.

• Nonmetal + Nonmetal • Share e-. • Single, double or triple bonds. • In the formation of either and Ionic bond or a covalent bond,

atoms lose, gain or share valence e-

Low melting point.

Gas or liquid at room temperature.

Soft solids

Non electrolytes, doesn’t conduct

electricity when dissolved in water.

• Describes how equally bonding electrons are shared between atoms .

• One atom might exert more of a force on the electron cloud than the other, electronegativity.

• The unequal sharing of electrons within a bond leads to the formation of an electric dipole.

The ability of atoms

in a molecule to

attract electrons to

itself.

1.8

Difference in electronegativities of two atoms in a bond

can be used to predict the type of bond formed.

Polar covalent bond:

Electrons are shared unequally.

Nonpolar covalent bond: Bond

between atoms with identical or

very similar electronegativities.

As the electronegativity difference increases the bond

becomes more polar.

There is no definite point at which one type of bond

stops and the next starts.

Electronegativity ranges Type of bond

0.0 to 0.4 nonpolar covalent

0.4 to 1.8 polar covalent

>1.8 Ionic

• H-H (2.1 – 2.1=0)

• C-H (2.5 – 2.1=0.4)

• O-H (3.5 – 2.1=1.4)

• Use electronegativities to classify each of

the following bonds.

1. H-Cl

2. MgO

3. H2

4. NaCl

5. O-K

6. O-H

7. Cl-As

Bonding of atoms in solid metallic

crystals.

A three-dimensional array of positive

ions that remain fixed in the crystal

lattice while loosely held valence

electrons move freely throughuot the

crystal.

Sharing a “sea of ve-”.

e- are free to move.

Good conductors of electricity and heat

Insoluble in water

Malleable (sheets)

Ductile (wires)

Shiny

Work on the EOC.