Atoms, Molecules & Ions

ATOMS, MOLECULES & IONS

A Review of Early Atomic Models, Periodic Table Development, and Nomenclature

Early Atomic Models

Early History Democritus (Greek)

world is made up of:: empty space tiny particles (atomos)

Aristotle (Greek) world is composed of continuous matter

(hyle) accepted until 17th Century

John Dalton agreed with Newton

and Boyle atoms were the basis

(no proof) English studied Lavoisier

and Proust (both were French)

Lavoisier Chemical change in a

closed system has equal mass before and after the change, matter is neither created nor destroyed Law of Conservation of

Mass

Proust Law of Definite Proportions Specific substances always contain

elements in the same ratio by mass example: H2O has a ratio of 1:8

(H:O)

Dalton’s Law Law of Multiple Proportions

certain elements can combine to form two or more different chemical compounds

Hydrogen and Oxygen can to form water (1:8) and peroxide (1:16)

Dalton’s Atomic Theory All matter is composed of extremely

small particles called atoms. Atoms of a given element are identical

in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties. (*)

Atoms cannot be subdivided, created, or destroyed. (*)

Atomic Theory con’t Atoms of different elements can

combine in simple, whole-number ratios to form chemical compounds.

In chemical reactions, atoms are combined, separated, or rearranged.

What does the * mean?

These tennets are no longer true today! #2 because of isotopes #3 because of subatomic particles

~1832: FARADAY:*PROPOSED EXISTANCE OF ELECTRON*PROPOSED ELECTRICITY WAS CARRIED BY CHARGED ATOMS ----IONS

~1879: CROOKES: INVENTED GAS DISCHARGE TUBE (CRT)RAY FROM - “POLE” (CATHODE) TO + “POLE (ANODE)

1895: ROENTGEN: CRT HIT TARGET, GET LOWER ENERGY EMISSIONS ---- X-RAYS

1896: BEQUEREL: DISCOVERED RADIOACTIVITY!

1897: JJ THOMSON USED CRT AND EXPLORED NATURE OF THESE “RAYS”

Subatomic Particles: Electron

J. J. Thomson (Eng) cathode ray tube

experiment proved that the atom is divisible

cathode (negative electrode)

anode (positive electrode)

ZnS- +

NO CHARGE ON PLATES

-

+

1. RAY DEFLECTED BY ELECTRIC & MAGNETIC FIELDNOT LIGHT; THEREFORE, PARTICLES

2. DEFLECTION TOWARD POSITIVE PLATEPARTICLES NEGATIVELY CHARGED

3. LARGE DEFLECTIONDETERMINED CHARGE/MASS (q/m) RATIO

q/m < 1/1000 THE MASS OF HYDROGEN ATOM!!!!

THOMSON:“FOUND” FARADAY’S ELECTRON

DETERMINED THE ATOM WAS NOT THE SMALLEST PARTICLE

1909: MILLIKEN DETERMINED THE EXACT CHARGE AND MASS OF THIS ELECTRON

ALL DATA INTEGRAL VALUES OF SAME NUMBER

q = -1.6 x 10-19 Cm = 9.1 x 10-31 kg

ABOUT 1/1800th OF THE HYDROGEN ATOM

TODAY: 1.60219 x 10-19 C9.10940 x 10-31 kg

Thomson’s Model: Plum Pudding

+

++

Subatomic Particles: Electron Robert Millikan (USA)

Oil Drop Experiment first to measure

the mass of an electron 9.109 x 10-28g

first to measure the charge of an electron (-1)

Subatomic Particles: The Nucleons What is a nucleon?

A nucleon is a particle that is found within the nucleus of an atom.

What are the major nucleons? Proton and the Neutron

Ernest Rutherford (New Zealand)

Gold Foil Experiment hit a thin piece of gold

foil with a beam of alpha radiation (positively charged) some of the beam

went through uninerrupted

some of the beam was deflected to the side or totally reflected

1911 -- RUTHERFORD’S “GOLD FOIL” EXPERIMENTZnS COATED

SCREEN

GOLDFOIL

STREAM OF a (ALPHA)

PARTICLES

1. MOST PASS THRU UNDEFLECTEDMOST OF ATOM VOLUME IS

EMPTY SPACE

2. SOME POSITIVE a PARTICLES DEFLECTED SLIGHTLY

NEAR COLLISIONS WITH MASSIVE, POSITIVELY CHARGED PARTICLE

3. 1 OF 20000 DEFLECT ACUTELYCROSS SECTION OF MASSIVE, POSITIVELY CHARGED PARTICLE IS 1/20000th THAT OF ATOM

RUTHERFORD FOUND THE NUCLEUS!!!

Rutherford’s Results Since the positively charged radiation

was repelled in certain areas, there was evidence for a positive entity inside of the foil Proton

This led to the idea of a central core that is very dense (nucleus)

Since some of the radiation passes through unharmed the foil must not be totally positive

ATOM MUST BE A VERY DENSE, POSTIVELY CHARGEDNULCLEUS SURROUNDED BY VERY LIGHT, NEGATIVELY

CHARGED ELECTRONS

QUANDRY:HEAVY PROTON (+ CHARGE) IN NUCLEUSLIGHT ELECTRONS ON OUTSIDE

COMBINED, ACCOUNT FOR ~ 1/2 THE ATOMIC MASSAND THE ATOM IS NEUTRAL!

1932: CHADWICK ISOLATED THE NEUTRON

IN NUCLEUSO CHARGEMASS ~ SAME AS PROTON

Chadwick If the nucleus is the

home of the majority of the mass, and the atom is electrically neutral there must be a neutral particle with a mass: neutron

Comparison of the Major Nucleons Proton

+1 Charge Mass:1.673 x 10-

24g number of protons

must equal the number of electrons for the atom to be neutral

p+

Neutron No charge Mass:1.675 x 10-

24g no

What holds it all together?

nuclear force holds the particles together in the nucleus

What are isotopes? Isotopes are atoms of the same

element that have different masses (different numbers of neutrons).

What do the numbers mean? Atomic Number

Z number of protons

Mass Number A number of protons

plus the number of neutrons

Where do you find the numbers?

Using the periodic table locate the symbol for the element that you are looking for. Inside the element’s square will be the numbers.

Writing Nuclides

XCopperOxygenSilver

The Isotopes of HydrogenName of Isotope Atomic # Mass # no

Protium 1 1 0Deuterium 1 2 1

Tritium 1 3 2

The Isotopes of Hydrogen

How many electrons, protons, and neutrons are found in a copper atom of mass # 65? Z = protons therefore protons = 29 Protons = Electrons therefore electrons

= 29 A - Z = neutrons so 65 - 29 = 36, there

are 36 neutrons Now try Oxygen and Calcium:

Ions Ions have charge due to an

imbalance in the number of protons and electrons. Atoms can either gain or lose electrons. If they gain electrons the ion is negative (anion), where is they lose electrons the charge is positive (cation).

Try these: O 2-

Ca 2+

Isotopes of Beanium Lab Purpose: to

determine the average atomic mass of a new element called Beanium

Beanium has 3 isotopes: black, black-eyed pea, and speckled bean.

If you are given a sample of Beanium, what do you need to know in order to calculate the average atomic mass.

REMEMBER, that means the average mass of all three isotopes!

Number of each type, mass of each type, and then total to get the average mass per atom (bean)

Data Table for Beanium Lab

Type of Isotope

Mass of Isotope

(g)

Number of

Isotope

Average Mass of Isotope

% of Each

PresentBlack

Black-eyed peaSpeckled

Total 100

Mass Spectrometer A gaseous sample is introduced into the

spectrometer and then it is bombarded by a stream of high-energy electrons.

Collisions between the electrons and the sample produce cations (usually 1+)

The positive beam passes through magnetic poles and bends, the more massive the sample the less the bend of the ray

A full diagram of a mass spectrometer

THE PERIODIC TABLE

Families of the Periodic Table

Column # Family Name Valence e- Oxidation #

1 Alkali Metals 1 1+

2 Alkaline Earth Metals

2 2+

3 Boron Family 3 3+/5-

4 Carbon Family 4 4+/4-

5 Nitrogen Family 5 3-

6 Chalcogens 6 2-

7 Halogens 7 1-

8 Noble Gases 8 0

Metals Loose electrons (oxidation) to form ions

that are positively charged (cations) Good conductors (allow energy to flow

through them) of heat and electricity Have 3 or less valence electrons

Non-metals Gain electrons (reduction) in order to

form negatively charged ions (anions) Good insulators (don’t allow heat or

electricity to flow through them) 4 or more valence electrons

Metalloids Found on the periodic table along the

“staircase” Have properties of both metals and

non-metals depending upon the particular situation

Also called the semi-metals

Molecules

Molecules An assembly of two or more atoms

tightly bound together Represented by a chemical formula

(written as a collection of element symbols and subscripts to indicate the # of each element)

Monatomic vs. Diatomic Some elements exist in nature as pairs

of atoms: diatomic “H and the 7” N O F

Br Cl I

Empirical Formula Simplest, true formula of a compound C2H8 can be simplified to CH4

Molecular Formula The TRUE formula for the ratio of

elements in a compound

Inorganic Nomenclature

51

HELLO……MY NAME IS

NAMING IONS

AND COMPOUNDS

52

MONOATOMIC CATIONS

ELEMENT + ION OR ELEMENT(VALENCE) + ION

Na1+ Ca2+

Fe2+

Fe3+

SODIUM

IRON (II) ION

IRON (III) ION

CALCIUM ION

Al3+ ALUMINUM ION

WHAT IS?

Be2+ Li1+

Co3+ Mn5+

BERYLLIUM ION LITHIUM ION

COBALT(III) ION MANGANESE(V) ION

Na SODIUM ION

53

ELEMENT ROOT + -IDE + ION

OXYGEN

IODINE

OX

IODIDE ION

MONOATOMIC ANIONS

O2-

I1-

WHAT IS?

S2- N3-

Br1- Se2-

SULFIDE ION NITRIDE ION

BROMIDE ION SELENIDE ION

OI

IONIDE

Suffix Naming System Higher Oxidation States for Transition

metals is indicated by the –ic suffix to the Latin stem Fe3+ is Iron (III) or ferric

Lower oxidation States for Transition metals is indicated by the –ous suffix to the Latin stem Fe2+ is Iron (II) or ferrous

Name these: Sn4+

Sn2+

SnCl2 FeCl3 FeCl2 Hg22+

56

POLYATOMIC ANIONS

COVALENTLY BONDED, NON-METAL ANIONS

CO32- = CARBONATE ION CN1- = CYANIDE ION

OXOANIONS: CENTRAL ATOM SURROUNDED BY OXYGEN

NO31-

NO21-

NITRATE IONNITRITE ION

1 LESS O

ClO1-

ClO21-

ClO31-

ClO41-

CHLORITE IONCHLORATE ION

HYPOCHLORITE ION

1 LESS O

PERCHLORATE ION

1 MORE OCO32-

HCO31-

CARBONATE IONHYDROGEN CARBONATE ION

57

NAMING IONIC COMPOUNDS

CATION ION + ANION ION = CATION ANION

Na1+ = SODIUM ION Cl1- = CHLORIDE ION

Na Cl

SODIUM CHLORIDE

CuBr

ZnO

Na2CO3

Fe2 (CO3) 3

COPPER (I) BROMIDE

ZINC OXIDE

SODIUM CARBONATE

IRON (III) CARBONATE

58

NAMING BINARY COVALENT COMPOUNDS

LESS ELECTRONEGATIVE ELEMENT FIRST:EXCEPTION H

RETAINS NAME

MORE ELECTRONEGATIVE ELEMENT: CHANGE END TO -IDE

MUST INDICATE NUMBER OF ATOMS WITH GREEK PREFIXES1 = MONO2 = DI3 = TRI4 = TETRA5 = PENTA

6 = HEXA7 = HEPTA8= OCTA9 = NONA10 = DECA

DO NOT USE MONO FOR FIRST ELEMENTDO NOT PUT TWO VOWELS TOGETHER

DECAOXIDE = DECOXIDE

59

NAME THE FOLLOWING:

NO

N2O

NO2

P2O5

H2O

CF4

P4O10

NH3

NITROGEN MONOXIDE (NITRIC OXIDE)

DINITROGEN MONOXIDE

NITROGEN DIOXIDE

DIPHOSPHORUS PENTOXIDE

TETRAPHOSPHORUS DECOXIDE

DIHYDROGEN MONOXIDE (WATER)

CARBON TETRAFLUORIDE

NITROGEN TRIHYDRIDE (AMMONIA)

NAMING ACIDS

BINARY:

UNLESS DISSOLVED IN WATER -- COVALENT

HBr

HYDROGENHYDRO BROMIDEBROMICHYDROBROMIC ACID

HFHI

HYDROFLUORIC ACIDHYDROIODIC ACID

POLYATOMICANIONS

-ITE = OUS OR -ATE = ICEXCEPTING S OR P

CO3 2- CARBON ATE IONH2 CO3 IC ACID

SO42- = SULFATE ION H2 SO4 = SULFURIC ACID

SO32- = SULFITE ION H2 SO3 = SULFUROUS ACID

Name these: HBr H2S H2SO4 H2SO3 HNO3 HN

Organic Nomenclature

Organic compounds Contain Carbon and hydrogen May contain oxygen, nitrogen, sulfur,

and occasionally other elements Defined by # of carbon atoms, type of

bonds between the atoms, and other types of atoms bonded to the carbons

All organic compounds contain Carbon, but not all Carbon containing compounds are organic!

Types of Organic CompoundsFamily of Organic Compounds

Type of Bonds between the Carbons

Alkanes SingleAlkenes DoubleAlkynes Triple

66

OverviewHydrocarbons:

•alkanes•alkenes•alkynes•arenes

Prefixes Indicating the # of Carbons present

# of C

1 2 3 4 5 6 7 8 9 10

Pre-

Meth

Eth

Prop

But Pent

Hex

Hept

Oct

Non

dec

68

R-H

Functional Groups in Hydrocarbons

•alkanes•alkenes•alkynes double bond

FG

triple bondFG

ringFG

Ar-H•arenes

arenes

HFG

69

Functionally substituted derivativesof alkanes

R-OH alcohol CH3CH2OH

R-X alkyl halide CH3CH2Cl (F,Cl,Br,I)

R-Der Class Example

R-NH2 amine CH3CH2NH2

R2C CR2

Oepoxide

H2C CH2

OR-O-R ether CH3CH2OCH2CH3

nitrileR-C N CH3CH2C N

R-NO2 nitroalkane CH3CH2NO2

R-SH thiol CH3CH2SH

70

Classes of cpds that contain a carbonyl group

R-Der Class Example

O

C

CH3CH2COHO

CHRaldehyde

CH3CH2COCH3

O

CRRketone

CH3CH2COOHO

COHR

carboxylicacid

O

CH

O

C

O

CO

H

O

CO

CH3CH2COOCH3

O

CORRester

71

Methane (CH4)

H

HC

HH 4 C-H s bonds

All carbons are sp3 hybridizedAlkane: CnH2n+2

H

CC

H H

HH

HEthane (C2H6)

1 C-C s bond

6 C-H s bonds

H CC

H

C

HH

H

H

HH

2 C-C s bond

8 C-H s bondsPropane (C3H8)

Name these compounds CH4

C2H6

C5H12

C10H22

73

CH4

CH3 CH3

methane

Alkane Nomenclature (IUPAC rules)

ethane

propane

butane

pentane

hexane

heptane

octane

nonane

decane

Unbranched Alkanes

Cyclic Hydrocarbons Drawn as geometric shapes where two

lines meet, a carbon is indicated Lines between carbons show number of

bonds between carbon Naming: use prefix cyclo- , then name

according to normal organic system

Name these:

The Special ring

Benzene(C6H6)

What’s so special about Benzene?

Congratulations we’re finally done with this unit!