A QUICK BONDING REVIEWA QUICK BONDING REVIEW

Why do atoms want to bond?

To achieve the octet rule

OCTET RULE: atoms want to have 8 valence electrons in their outer most shell because it makes them stable

What is the difference between a bond and a compound?

A bond is the link between two (or more) elements in a compound

Na---Cl

it involves valence electrons

A compound is what two (or more) elements linked together is called

NaCl

What are the different types of bonds and/or compounds?

IONIC

COVALENT

METALLIC

IONIC BOND

bond between a metal and a nonmetal involves transfer of electrons one atom gains electrons (anion); the other atom loses

electrons (cation) attraction between oppositely charged ions holds ions

together strongest bond the compound with an ionic bond is also called a

FORMULA UNIT example: the bond between sodium & chlorine in NaCl

COVALENT BOND

bond between two nonmetals there is “cooperation between valence electrons” or sharing

of electrons neither atom loses e- easily; both attract e- by sharing e-, outer energy level is filled attraction between nucleus and shared e- holds atoms

together strong bond, but weaker than ionic the compound with a covalent bond is also called a

MOLECULE example: the bond between carbon & oxygen in CO2

METALLIC BONDS between 2 metals

positive nuclei of atoms surrounded by free-moving electrons

all electrons attracted by all the nuclei at the same time

NAMING AND WRITING NAMING AND WRITING CHEMICAL FORMULASCHEMICAL FORMULAS

Naming Ionic Compounds

Remember: between a metal & nonmetal

1.

2.

fluorine becomes fluoride

sulfur becomes sulfide

oxygen becomes oxide

phosphorus becomes phosphide

nitrogen becomes nitride

iodine becomes iodide

Example: LiBr

Name metal: Name nonmetal: Add –IDE ending:

More Examples

CaCl2Calcium chloride

Notice that the subscripts do not matter in the name

Rb2O

Rubidium oxide

Writing Ionic Compounds

Remember ionic charges!

(also called oxidation numbers)• Alkali metals (+1)• Alkaline Earth metals (+2)• Boron family (+3)• Nitrogen family (-3)• Oxygen family (-2)• Halogens (-1)

Remember to use your

Periodic Table!

Writing Ionic Compounds con’t

1.

2.

Example: aluminum oxide

Determine each element’s charge:aluminum oxygen

Criss-cross the charges:

(note: you may eliminate a subscript of 1)

More Examples

Lithium oxide

Barium bromide

= Li2O

=BaBr2

What is a polyatomic ion?

It is an ion (or has a charge) and is composed of more than one element covalently bonded

Example: NO3 –1

This is the nitrate ion

the whole thing has a charge of –1 and

it is composed of 1 nitrogen atom

and 3 oxygen atoms

See list on page 173).

Naming Compounds…with polyatomic ions

1.

2.

Remember that the subscripts do not matter in the name of IONIC compounds

Example: Ca(NO3)2

Name metal or positive polyatomic ion:

Name nonmetal or negative polyatomic ion:

Ca(NO3)2

More Examples

NH4Br

ammonium bromide

Mg(OH)2

magnesium hydroxide

Writing Compounds…with polyatomic ions

1.

2.

3. Use (parenthesis) if polyatomic ion has a subscript

Example: barium perchlorate

Determine each charge:

Criss-cross:

More Examples

Potassium Cyanide

K+1 CN-1

KCN

Magnesium phosphate

Mg+2 (PO4)-3

Mg3(PO4)2

Other thoughts…

Write the formula for beryllium sulfide

Beryllium: Be +2 Sulfide: S -2

you would think… Beryllium sulfide Be2S2

But cancel subscripts to make….BeS