the periodic table and naming simple compounds chemistry 142 a james b. callis, instructor winter...

The Periodic Table and

Naming Simple Compounds

Chemistry 142 A

James B. Callis, Instructor

Winter Quarter, 2006

Lecture #6

Classification of the Elements

• Most of the elements are metals - metallic luster, ability to conduct electricity and heat, and malleability.

• The remaining elements are classified as nonmetals - no luster, poor conductors of electricity and heat and brittleness.

Sub-Classes of Metals• Alkali metals - (lithium, sodium, potassium, rubidium

and cesium) - soft, low melting points, react with water to liberate hydrogen, form 1:1 compounds with chlorine.

• Alkaline earths - (beryllium, magnesium, calcium, strontium, barium and radium) - react in a 1:2 ratio with chlorine.

• Transition metals - (e.g. iron, copper, silver, gold, tungsten and cobalt) - structural metals

• Metalloids - (antimony, arsenic, boron, silicon and tellurium) - intermediate between metals and nonmetals.

Non-Metals

• Chalcogens - (oxygen, sulfur, selenium and tellurium) - form 1:1 compounds with alkaline-earths, but 2:1 compounds with alkali-metals.

• Halogens - (fluorine, chlorine, bromine and iodine) - highly reactive and form 1:1 compounds with alkali-metals.

• Noble gases - (helium, neon, argon, krypton, radon) - virtually inert to chemical reactions.

Periodic Variation

• When the properties of the elements are plotted against atomic number, we observe a periodic variation in their properties.

• The boundaries of the periods seem to be marked by the appearance of the noble gases at 2, 10, 18, 36, 54 and 86 amu.

• The variations in both melting point and atomic radius seem to correlate (inversely).

• The different element classifications also appear cyclically in this periodic variation.

Variation of Atomic Radius with Atomic Number

0

0.5

1

1.5

2

2.5

3

0 10 20 30 40 50 60 70 80 90 100

Atomic Number

Ato

mic

Rad

ius,

A

Periodic Variation in Properties

1

10

100

1000

10000

0 10 20 30 40 50 60 70 80 90 100

Atomic Number

Boi

ling

Poi

nt, K

0

0.5

1

1.5

2

2.5

3

Ato

mic

Rad

ius,

A

Boiling Point K

Atomic radius (Å)

The Periodic Table• A two dimensional classification scheme for the elements.

The columns or groups arrange the elements by chemical classification, as discussed above. The chemical variation across the rows or periods reflect the cyclic variation exhibited in the graphs above.

• The periodic table is not only an organizing principle, but it has (had) predictive power as well.

• As valuable as the periodic table is, the explanation of its organization was not obvious. It was not until the advent of quantum mechanics that the electronic structure of the atoms could be used to explain the periodic variation in properties.

Groups in the Periodic Table

Main Group Elements (Vertical Groups) Group IA - Alkali Metals Group IIA - Alkaline Earth Metals Group IIIA - Boron Family Group IVA - Carbon Family Group VA - Nitrogen Family Group VIA - Oxygen Family (Calcogens) Group VIIA - Halogens Group VIIIA - Noble GasesOther Groups ( Vertical and Horizontal Groups)Group IB - 8B - Transition MetalsPeriod 6 Group - Lanthanides (Rare Earth Elements)Period 7 Group - Actinides

O

S

Se

Te

Po

N

P

As

Sb

Bi

C

Si

Ge

Sn

Pb

B

Al

Ga

In

Tl

ZnCu

Cd

Hg

Ag

Au

Ni

Pd

Pt

Co

Rh

Ir

Fe

Ru

Os

Mn

Tc

Re

Cr

Mo

W

V

Nb

Ta

Ti

Zr

Hf

Sc

Y

La

Ac

The Periodic Table of the Elements

The Alkali Metals

The Alkaline Earth Metals

Ce Pr Nd PmSmEu Gd Tb Dy Ho Er TmYb Lu

Th Pa Np PuAmCmBk Cf Es FmMd No LrU

H

Li

Na

K

Rb

Cs

Fr

Be

Mg

Ca

Sr

Ba

Ra Rf Sg

The Halogens

The Noble Gases

He

Ne

Ar

Kr

Xe

Rn

F

Cl

Br

I

At

Du Bo HaMe

The Periodic Table of the ElementsH

Li Be

NaMg

K Ca Sc

Rb

Cs

Fr

Sr

Ba

Ra

Ti V CrMn Fe

Y

La

Ac

Co Ni Cu Zn

Zr

Hf

Nb

Ta

Rf

Mo

W

Tc

Re

Ru

Os

Rh

Ir

Pd

Pt

Ag

Au

Cd

Hg

F

He

Ne

ArCl

Br Kr

Xe

Rn

I

At

Ce Pr Nd Pm

Th

SmEu Gd Tb Dy Ho Er Tm Yb Lu

Pa U Np PuAmCm Bk Cf Es FmMd No Lr

Boron family

B

Al

Ga

In

Tl

Carbon Family

C

Si

Ge

Sn

Pb

Nitrogen family

N

P

As

Sb

Bi

Oxygen Family

O

S

Se

Te

Po

Du Sg Bo Ha Me

O

S

Se

Te

Po

N

P

As

Sb

Bi

C

Si

Ge

Sn

Pb

B

Al

Ga

In

Tl

The Periodic Table of the Elements

Lanthanides: The

Rare Earth ElementsThe Actinides

F

Cl

Br

I

At

H He

Ne

Ar

Kr

Xe

Rn

Li

Na

K

Rb

Cs

Fr

Be

Mg

Ca

Sr

Ba

Ra

Ce

The Transition Metals

Pr Nd PmSmEu Gd Tb DyHo Er TmYb Lu

Th Pa U Np PuAmCmBk Cf Es FmMd No Lr

Sc Ti V CrMn

Y

La

Fe Co Ni Cu Zn

Zr NbMo Tc Ru Rh PdAg Cd

Hf Ta W Re Os Ir Pt Au Hg

Ac Rf Sg HaDu Bo Me

Naming Binary Compounds (Type I; Ionic)

• The cation is always named first and the anion second.

• A monatomic cation takes its name from the name of the element, e.g. Na+ is called sodium in the names of compounds containing this ion.

• A monatomic anion is named by taking the first part of the element and adding –ide, e.g. Cl- is chloride.

Type I

Problem 6-1: Give the Name and Chemical Formulas of the Compounds formed from the following pairs of Elements

a) sodium and oxygen Na2O sodium oxide

b) zinc and chlorine c) calcium and fluorine CaF2 calcium fluoride

d) strontium and nitrogen

e) hydrogen and iodine HI hydrogen iodide

f) scandium and sulfur

Naming Binary Compounds (Type II; Ionic)

• Applies to cations that can take on alternate charge states

• Using the principle of charge balance determine the cation charge.

• Include in the cation name a Roman numeral indicating the charge.

Type II

Determining Names and Formulas of Ionic Compounds of Elements That Form More Than One Ion.

Problem 6-2: Give the systematic names for the formulas or the formulas for the names of the following compounds.

a) iron (III) sulfide - Fe is 3+, and S is 2- therefore the compound is: Fe2S3

b) CoF2 -

c) stannic oxide - Stannic is the common name for tin (IV), Sn4+, the oxide ion is O2-, therefore the formula of the compound is: SnO2

d) NiCl3 -

Ionic Compounds with Polyatomic Ions

• Polyatomic ions are assigned special names that must be memorized.

• Special rules apply to anions that contain an atom of a given element and different numbers of oxygen atoms. These anions are called oxyanions.

Start learning these boldface ones.

Rules for Families of OxoanionsFamilies with Two Oxoanions

The ion with more O atoms takes the nonmetal root and the suffix “-ate”.

The ion with fewer O atoms takes the nonmetal root and the suffix “-ite”.

Families with Four Oxoanions (usually a Halogen)The ion with most O atoms has the prefix “per-”, the nonmetal root and the suffix “-ate”.

The ion with one less O atom has just the suffix “-ate”.

The ion with two less O atoms has the just the suffix “-ite”.

The ion with three less O atoms has the prefix “hypo-” and thesuffix “-ite”.

NAMING OXOANIONS - EXAMPLES

Prefixes Root Suffixes Chlorine Bromine Iodine

per “ ” ate perchlorate perbromate periodate [ ClO4

-] [ BrO4-] [ IO4

-] “ ” ate chlorate bromate iodate [ ClO3

-] [BrO3-] [ IO3

-]

“ ” ite chlorite bromite iodite [ ClO2

-] [ BrO2-] [ IO2

-]

hypo “ ” ite hypochlorite hypobromite hypoiodite [ ClO -] [ BrO -] [ IO -]

No.

of

O a

tom

s

Binary Compounds (Type III; Covalent –

Contain Two Nonmetals• The first element in the formula is named first,

using the full element name.• The second element is named as if it were an

anion. • Prefixes are used to denote the numbers of atoms

present.• The prefix mono- is never used for naming the

first element, e.g. CO is carbon monoxide.

Examples of Names and Formulas of Oxoanions and Their Compounds - I

• KNO2 BaSO3 barium sulfite

• Mg(NO3)2 magnesium nitrate Na2SO4

• LiClO4 lithium perchlorate Ca(BrO)2 calcium hypobromite

• NaClO3 Al(IO2)3 aluminum iodite

• RbClO2 rubidium chlorite KBrO3

• CsClO LiIO4 lithium periodate

Examples of Names and Formulas ofOxoanions and their Compounds - II

• calcium nitrate ammonium sulfite (NH4)2SO3

• strontium sulfate SrSO4 lithium nitrite

• potassium hypochlorite KClO lithium perbromate LiBrO4

• rubidium chlorate calcium iodite Ca(IO2)2

• ammonium chlorite NH4ClO2 boron bromate

• sodium perchlorate magnesium hypoiodite Mg(IO)2

Problem 6-3: Determining Names and Formulas of Ionic Compounds Containing Polyatomic Ions

a) magnesium perchlorate

b) (NH4)2SO3

c) calcium nitrate

Naming Acids

1) Binary acids solutions form when certain gaseous compounds dissolve in water. For example, when gaseous hydrogen chloride (HCl) dissolves in water, it forms a solution called hydrochloric acid. Prefix hydro- + anion nonmetal root + suffix -ic + the word acid hydrochloric acid

2) Oxoacid names are similar to those of the oxoanions, except for two suffix changes: Anion “-ate” suffix becomes an “-ic” suffix in the acid. Anion “-ite” suffix becomes an “-ous” suffix in the acid. The oxoanion prefixes “hypo-” and “per-” are retained. Thus, BrO4

-

is perbromate, and HBrO4 is perbromic acid; IO2- is iodite, and

HIO2 is iodous acid.

Determining Names and Formulas ofAnions and Acids

Problem 6-4: Name the following anions and give the names and formulas of the acid solutions derived from them:

a) I - b) BrO3- c) SO3

2- d) NO3- e) CN -

Solution: a) The anion is

b) The anion is bromate; and the acid is bromic acid, HBrO3

c) The anion is

d) The anion is nitrate; and the acid is nitric acid, HNO3

e) The anion is

Names and Formulas of Binary Covalent Compounds

1) The element with the lower group number in the periodic table is the first word in the name; the element with the higher group numberis the second word. (Important exception: When the compound contains oxygen and a halogen, the halogen is named first.)

2) If both elements are in the same group, the one with the higher period number is named first.

3) The second element is named with its root and the suffix “-ide.”

4) Covalent compounds have Greek numerical prefixes toindicate the number of atoms of each element in the compound. Thefirst word has a prefix only when more than one atom of the elementis present; the second word always has a numerical prefix.

Determining Names and Formulas of Binary Covalent Compounds

Problem 6-5: What are the name or chemical formulas of the following chemical compounds:

a) carbon dioxide b) PCl3 c) Give the name and chemical formula of the compound formed from two P atoms and five O atoms.

Solution:

a) carbon dioxide

b) PCl3

c) The compound formed from two P atoms and five O atoms

Answers to Problems in Lecture #61. (b) ZnCl2 , Zinc Chloride; (d) Sr3N2 , Strontium Nitride;

(f) Sc2S3 , Scandium Sulfide2. (b) Cobalt (II) Fluoride; (d) Nickel (III) Chloride3. (a) Mg( ClO4)2 ; (b) Ammonium Sulfite; (c) Ca(NO3)2

4. (a) iodide, hydroiodic acid, HI; (c) sulfite, sulfurous acid, H2SO3 (e) cyanide, hydrocyanic acid, HCN

5. (a) CO2 ; (b) phosphorous trichloride; (c) diphosphorous pentaoxide