Writing Formulas and Naming CompoundsWriting Formulas and Naming Compounds

SC StandardsSC Standards

PS-4.5Predict the ratio by which the representative elements combine to form binary ionic compounds, and represent that ratio in a chemical formula.

PS-4.5Predict the ratio by which the representative elements combine to form binary ionic compounds, and represent that ratio in a chemical formula.

“Perhaps one of you gentlemen would mind telling me just what is outside the window that you find so attractive..?”

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Warm-up Distinguish if the compounds on the board are ionic or covalent

Warm-up Distinguish if the compounds on the board are ionic or covalent

Types of BondsTypes of Bonds

IonicCovalentMetallic

IonicCovalentMetallic

Binary Ionic CompoundsBinary Ionic Compounds

Binary compound – compound composed of only two elements

KCl MgCl2 AlCl3

Binary compound – compound composed of only two elements

KCl MgCl2 AlCl3

Element ChargeElement Charge

Oxidation number – the charge on an ion

Group 1 +1Group 2 +2Group 16 -2Group 17 -1

Oxidation number – the charge on an ion

Group 1 +1Group 2 +2Group 16 -2Group 17 -1

Writing Chemical FormulasWriting Chemical Formulas

In order for you to write formulas, you must know the elements charge or oxidation

number

In order for you to write formulas, you must know the elements charge or oxidation

number+1

+2 +3 +4 -3 -2 -1

0

How do we use an oxidation number?

How do we use an oxidation number?

When an element gains or loses an electron it develops a charge…

When an element gains or loses an electron it develops a charge…

What is sodium’s oxidation number?

What is chlorine’s oxidation number?

How do they bond?How do they bond?

A compound is always neutral.

The oxidation numbers always add up to zero.

In other words – the amount of positive charge must equal the amount of negative

charge

A compound is always neutral.

The oxidation numbers always add up to zero.

In other words – the amount of positive charge must equal the amount of negative

charge

Na+ + Cl- NaCl

Transition Metals

- most transition metals can form many different ions so a roman numeral is used to show its oxidation number

copper (I) Cu+1

copper (II) Cu+2

Determining the Formula for an Ionic Compound

Write down the ions of each element

Determine the number of each of the ions it takes to make a compound with no charge

Write down the formula using subscripts to show how many of each ion it took

What is the formula for the compound

that forms between magnesium and phosphorous?

Mg+2 P-3

3(+2) + 2(-3) = 0

Mg3P2

You Try it!!You Try it!!

Write the formulas for the compounds that form between the following pairs:

1. Sodium and sulfur2. Calcium and bromine3. Iron (III) and iodine4. Copper (I) and phosphorus

Write the formulas for the compounds that form between the following pairs:

1. Sodium and sulfur2. Calcium and bromine3. Iron (III) and iodine4. Copper (I) and phosphorus

Polyatomic IonsA Group of Atoms that Function as a Single Unit

in Compounds and Chemical Reactions

ammonium - NH4+1

hydroxide - OH-1

nitrate - NO3-1

carbonate - CO3-2

sulfate - SO4-2

phosphate - PO4-3

What is the formula for the compound between…

potassium and sulfate? ammonium and nitride?

K+1 SO4-2

2(+1) + (-2) = 0 K2SO4

NH4+1 N-3

3(+1) + (-3) = 0 (NH4)3N

Steps for Naming

Name the (+) ion (always

first)

1A or 2A metal or Ag, Cd, Zn, Al?

Just name it

NH4?Just name it

Group 3-16 metal?Name with Roman numeral

Name the (-) ion

Monoatomic?- name with -ide ending

Polyatomic? - Just name it

Practice Naming Compounds…

Sodium and Sulfur Na2SCalcium and BromineCaBr2

Iron(III) and Iodine FeI3Copper (I) and PhosphorusCu3P

Sodium SulfideCalcium BromideIron (III) Iodide

Copper (I) Phosphide

Covalent BondingCovalent Bonding

Covalent Bonds occur when electrons are being sharedCovalent Bonds occur when electrons are being shared

Electrons shared equallyElectrons shared unequally

e- are shared equallysymmetrical e- densityusually identical atoms

e- are shared equallysymmetrical e- densityusually identical atoms

Nonpolar Covalent Compounds

Nonpolar Covalent Compounds

Nonpolar Covalent Compounds

Nonpolar Covalent Compounds

Examples: The Magnificent Seven… I2, Br2, Cl2, F2, O2, N2, H2

Examples: The Magnificent Seven… I2, Br2, Cl2, F2, O2, N2, H2

+ -

Polar Covalent Compounds

Polar Covalent Compounds

e- are shared unequallyasymmetrical e- density

results in partial charges (poles)

e- are shared unequallyasymmetrical e- density

results in partial charges (poles)

Polar Covalent Compounds

Polar Covalent Compounds

Examples: H2O and HCl

Examples: H2O and HCl

•Nonpolar

•Polar

• Ionic

View Bonding Animations.

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