chemical nomenclature. chemistry - today chemical formulas memorizing 55 elementsmemorizing 55...

Chemical Nomenclature

Chemistry - Today•Chemical Formulas

•Memorizing 55 elements

•Rules for naming binary compounds.

NOTES

I. ElementsA. Symbols: come from the first

letter, or first two letters of the element’s name.

B. Learn all 55 given elements. See the web page.

C. Elements Test next Thursday (A) and Friday (B)

Naming Inquiry

Formula Name NaCl Sodium Chloride KI Potassium Iodide MgCl2 Magnesium Chloride

What is a binary compound?

Naming Inquiry


What does the chemical formula of each indicate?

Naming Inquiry

Formula Name NaCl Sodium Chloride KI Potassium Iodide MgCl2 Magnesium chloride

Why are there two chlorines for one magnesium?

Naming Inquiry


What are some naming rules that can be discovered from

these examples?

II. Chemical Formula: represents the composition of the compound.

A. Tells the proportion of each element relative to each other.

1. Subscripts are used to indicate the number of atoms of each element in the compound.

2. The subscript follows the atom it refers to.

II. Formula: represents the composition of the compound.


B. All atoms have oxidation numbers (valence charge).

C. Polyatomic ions behave as though they were a single atom. They have oxidation numbers as well. Examples: SO42- (sulfate), NO3- (nitrate)

II. Formula: represents the composition of the compound.


B. All atoms have oxidation numbers (valence charge).

C. Polyatomic ions behave as though they were a single atom. They have oxidation numbers as well.

D. The concept of valence or charge will be used to write the formulas.


1. Valence is either (+) or (-).

2. In all compounds the sum of all valences is zero.

3. Metals are always (+).

4. Non-metals may be either.

5. Most polyatomic ions are (-).


1. Example 1: Lithium Chloride …Li 1+ and Cl 1-, so the formula must be LiCl.

2. Example 2: Calcium Oxide …Ca 2+ and O 2-, so the formula must be CaO

3. Example 3: What about Lithium Oxide?

4. Answer: you need two lithium atoms for every one oxygen to balance…Li2O

E. Atoms that have a constant valence: (+1) = first column and Ag, (+2) = 2nd column plus Zn and Cd, and (+3) Al. (See columns already marked on your periodic table.)

F. Some Atoms can have multiple valences (charges, or oxidation states) – see page 24 in the blue book.

III. Naming Binary Salts & Writing their Formulas

A. Metal plus a non-metal (two elements).

B. Metals named first, non-metal second with an “ide” suffix.

C. Many metals have multiple valences (+ oxidation states), therefore their particular valence must be indicated using the stock system where a Roman numeral indicates which valence is used.

C. Many metals have multiple valences – examples:

1. Example: Iron can be +2 or +3, therefore Fe +2 is named Iron (II), and Fe +3 is named Iron (III).

2. The Latin names ferrous (for Fe +2) and ferric (for Fe+3) may also be used.

IV.Salts with Radicals (polyatomic ions)

A. Four ways to identify salts1. Metal + non-metal (binary)2. Metal + Radical3. Radical + Non-metal4. Radical + Radical


B. Naming Salts (other than binary)1. Name of metal + name of radical2. Name of radical + name of non-

metal or radical


C.Memorization of Polyatomic Ions (Radicals)

1.– “ite” (one less oxygen)

2. Two fewer oxygen’s then the name starts with “hypo” and ends with “ite”.

IV. Salts with Radicals (polyatomic ions)

C.Memorization of Polyatomic Ions (Radicals) - continued

3. If there is one more oxygen then use “per” as a prefix and “ate” as a suffix.

4. Examples: NaNO3, NaNO2, NaNO, and NaNO4

V. Naming Acids1. Can be named as common salts if not dissolved in water.2. Binary Acids: hydrogen + a non-metal.

a. Change hydrogen hydro

b. Change -ide -ic. c. Followed by the word

acid.d. Example: HCl is

Hydrochloric acid

V. Naming Acids - continued3. Ternary Acids:

hydrogen + a radical.a. Change –ate to –

ic.b. Change –ite to –

ous.c. Also uses hypo

and per. (same as before)

d. Ex: HNO3 Nitric Acid

See pages 29-30 in the blue book for more help on naming acids.

Assignment: More practice naming salts and naming acids!

Naming Compounds Test:

VI. Molecular Compounds

A. Greek System of naming1. Only used for 2 non-metals

2. Ends in “ide”

3. Number of each kind of atom is indicated by a Greek numerical prefix (list on next slide)

Greek prefixes used for molecular compounds.

Mono = 1 Hexa = 6

Di = 2 Hepta =7

Tri = 3 Octa =8

Tetra= 4 Nona = 9

Penta= 5 Deca = 10

VI. Molecular Compounds

Non-metal + Non-metal

Formula NameCO2 Carbon Dioxide

N2O5 Dinitrogen Pentoxide

N2O4 _______________

_____ Phosphorous Trichloride

P4O10 _______________

A few more rules for naming binary compounds of non-metals:

1. The prefix mono- is usually omitted except where it is used for emphasis, as in carbon monoxide.

2. Common usage omits the double vowel – as in the example above carbon monoxide is not carbon mono-oxide.

Naming Test – Thursday

Assignments due on Thursday 10/15:

Worksheets #1 – 9

chemical nomenclature. chemistry - today chemical formulas memorizing 55 elementsmemorizing 55...

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