BondingBonding

Practical Chemistry Practical Chemistry 20052005

How are new substances formed?How are new substances formed?

New substances are formed when two New substances are formed when two or more atoms or more atoms CHEMICALLY BONDCHEMICALLY BOND together.together.

The resulting substance is UNIQUE The resulting substance is UNIQUE both both chemicallychemically & & physicallyphysically..

It’s all about the electrons!It’s all about the electrons!

Remember Remember electrons?electrons?– Tiny particles that Tiny particles that

are located outside are located outside of the nucleus of an of the nucleus of an atomatom

The Periodic Table: your best friendThe Periodic Table: your best friend

How do you figure out how many electrons How do you figure out how many electrons an element has?an element has?

Electron IdentificationElectron Identification

Determine the # of electrons in the Determine the # of electrons in the following:following:

1. Ca1. Ca

2. P2. P

3. N3. N

4. Mg4. Mg

How Electrons are OrganizedHow Electrons are Organized

Electrons are arranged in energy levels Electrons are arranged in energy levels around the nucleus of an atomaround the nucleus of an atom

1st energy level = 2 electrons1st energy level = 2 electrons

2nd energy level = 8 electrons2nd energy level = 8 electrons

3rd energy level = 8 3rd energy level = 8 (or 18) (or 18) electronselectrons

Practice Drawing AtomsPractice Drawing Atoms

Take a few minutes to practice drawing Take a few minutes to practice drawing atoms and their electrons …..atoms and their electrons …..

HeliumHelium

OxygenOxygen

MagnesiumMagnesium

CarbonCarbon

Valence ElectronsValence Electrons

The outermost electrons (Valence The outermost electrons (Valence electrons) are the ones involved in electrons) are the ones involved in bonding.bonding.

Lewis Dot Notation – shows only the Lewis Dot Notation – shows only the valence electrons.valence electrons.

““Happy Atom” TheoryHappy Atom” Theory

Atoms want Atoms want 88 (eight) valence electrons in (eight) valence electrons in their their outermost orbitals. outermost orbitals. Once atoms have Once atoms have a filled outera filled outer shellshell, they , they are STABLE, or “happy”are STABLE, or “happy”Chemical Chemical bondingbonding allows atoms get the allows atoms get the electrons that they needelectrons that they need

An Easier Way….An Easier Way….You can figure out how many electrons You can figure out how many electrons are going to be involved in bonding by are going to be involved in bonding by looking at the periodic tablelooking at the periodic table

Types of Bonding ITypes of Bonding I

IONIC BONDINGIONIC BONDING

Na

(1 electron)

F

(7 electrons)

NaF

Both have 8 electrons because now the second shell of Na is its outermost shell.

IONIC BONDING (cont…)IONIC BONDING (cont…)

Electrons are ripped off one atom by Electrons are ripped off one atom by another atom. This creates IONS.another atom. This creates IONS.

Occurs between METALS and Occurs between METALS and NONMETALSNONMETALS

Identify the following elements as metals Identify the following elements as metals or non-metals…..or non-metals…..

Types of Bonding IITypes of Bonding II

COVALENT BONDINGCOVALENT BONDING– Electrons are SHARED between two atomsElectrons are SHARED between two atoms– Occurs between NONMETAL and Occurs between NONMETAL and

NONMETALNONMETAL

Identifying Different BondsIdentifying Different Bonds

Practice identifying the type of Practice identifying the type of bonding in each compound bonding in each compound below…… below……

(SEE WORKSHEET)(SEE WORKSHEET)

THE ENDTHE END