Subatomic ParticlesA.K.A. particles that are smaller than an atom.

Name Symbol Charge Mass Location Function

Proton*

Neutron*

Electron

** Amu (atomic mass unit) is defined as 1/12 of the atomic mass of the carbon-12 isotope (1.6605402 x 10-27 kg)

* protons and neutrons are collectively called nucleons because they are located in the nucleus.

p+ +1 ~1amu** nucleus Attract electrons

n 0 ~1amu nucleusBuffer p+ to p+ repulsions to help stabilize the nucleus

e- -1 1/2000 amu

Electron clouds around the nucleus

Participate in chemical reactions

If a football stadium represented the size of an atom (the electron clouds surrounding the nucleus), the nucleus is estimated to be about the size of a nickel.

Atomic Number and Mass NumberAtomic number – number of

protons in an atom. Also indicates the name of the element (Periodic Table).

Mass number – number of nucleons (protons and neutrons) in an atom. It is always a whole #, never a decimal approximation. It is specific to a particular atom, therefore it is not on the Periodic Table.

IsotopesIsotopes – atoms that have the same number of

protons but different number of neutrons

Atomic number

Mass number

Therefore it has 8 neutrons

Hyphen Notation and Symbol Notation for atoms.

Carbon-14 C6

14

Atomic MassAtomic Mass – average of all naturally occurring isotopes. Be

careful not to confuse atomic mass and mass number. It is the number found on the Periodic Table.

6

12.011C

Atomic mass

Based on this atomic mass, the most abundant Carbon isotope would probably be Carbon-12.

Atomic Number

IonsIons are atoms that have become charged due to an imbalance between protons and electrons.

Ions can only be formed by the loss or gain of electrons.

The loss or gain of protons, on the other hand does not form ions because if protons are lost or gained, the nucleus changes (nuclear reaction) and the atom becomes a new element.

Cation AnionIs an atom that has LOST electrons and become POSITIVELY charged.

Is an atom that has GAINED electrons and become NEGATIVELY charged.

The “t” in the word cation looks like a plus sign, therefore it should help you remember that it is positively charged.

Symbols for IonsSymbols for ions are simply the elements symbol with a superscript to indicate the charge of the ion.

Sodium +1 cation

Chlorine -1 anion

Lead +4 cation

Na+

Pb+4

Cl -

Summary of Terms• Ion- an atom that has become charged due to a loss or

gain of electrons. (cations and anions)

• Atomic Number- indicates the # protons as well as the # electrons if the atom is neutral. It also indicates the identity of the element.

• Mass Number- the sum of protons plus neutrons. This number is specific to an individual atom.

• Atomic Mass- the average of mass #’s for all the naturally occurring isotopes for a given element.

• Isotopes- atoms of the same element (same # protons) that have different # of neutrons.

Applying the Concepts

11047 Ag

20077 Ir

221 482 Pb

Indicate the number of protons, neutrons and electrons for each species below. Also indicate whether each species is cation, anion, or an atom.

Silicon-26

# protons # neutrons # electrons species

47

77

82

14

63

123

139

12

47

77

78

14

atom

atom

atom

+4 cation

More Examples

H11

8940 Zr

179 674W

Gold-198

# protons # neutrons # electrons species

26

40

79

74

35

49

119

105

24

40

79

68

+2 cation

atom

+6 cation

atom

61 226 Fe

1 0 1 atom

The Periodic Table

the organization of elements into groups by similar chemical properties

Periodic ClassificationGroups/families – the vertical columns of the periodic table

Periods – the horizontal rows of elements in the periodic table

Period

Group/Family

Types of ElementsMetals – an element that is a good electrical conductor and a good heat conductor. Commonly form cations.

Nonmetals – an element that is a poor conductor of heat and electricity. Commonly form anions.

Metalloids – an element that has some characteristics of metals and some characteristics of nonmetals

Copper: Metal

Sulfur: Nonmetal Silicon: Metalloid

Groups All groups have similar chemical properties

Group 1: Alkali Metals – have a silvery appearance and are very soft in pure state. Very reactive. Not found in nature as a free element. Generally form +1 cations in ionic compounds. They like to bond with anions.Group 2: Alkaline-Earth – harder, denser, and stronger than alkali metals. Fairly reactive. Not found in nature as a free element. Generally form +2 cations in ionic compounds. Groups 3-12: Transition Metals – good conductors of electricity, high luster. Less reactive than alkali/alkaline-earth. Cation charges vary.

Rubidium: Alkali Magnesium: Alkaline-Earth

Gold: Transition

Groups (continued)

Group 17: Halogens– most reactive nonmetals. Combine with most metals to form salts. Generally form –1 anions in ionic compounds.

Group 18: Noble Gases– inert gases.

Group 16: Chalcogens– include non-metals and metalloids. Generally form –2 anions in ionic compounds.

2 2I2

Notice the labeling scheme for the groups on this periodic table.

Roman numerals and capital letters are used. Groups with capital letter A are considered the representative elements.

The more recent labeling scheme is to simply number them from 1 to 18 from left to right

1

2

8

14 15 16 17

18

9 10 11 12

13

3 4 5 6 7

Chemical PropertiesElements in the same Group/Family will have similar chemical properties.For example if Lithium combines with chlorine to

form LiCl, then all the other alkali metals will react similarly. NaCl, KCl, RbCl, CsCl

Bromine readily reacts with magnesium to form MgBr2, then all the other halogens will react similarly. MgF2, MgCl2, MgI2

The MoleA mole, in chemistry, is an SI base unit for counting how many.

It is similar to a dozen because a dozen indicates “how many”. In fact a dozen things = 12 of those things.

Except in chemistry atoms and molecules are very small, therefore we would need a lot of them to observe properties about a substance. A dozen atoms or a dozen molecules is just not practical, therefore we need a much larger #.

The Mole, cont.

Similarly, 1 mole atoms = 6.02 x1023 atoms

It is similar to a dozen in that it indicates “how many”, 1 dozen atoms = 12 atoms

Similarly, 1 mole molecules = 6.02 x1023 molecules

It is similar to a dozen, 1 dozen molecules = 12 molecules

A mole means 6.02 x1023 “things” The things are generally atoms, molecules or ions.

Avogadro’s number

The Mole, cont.*IMPORTANT*

Would a dozen pencils have the same mass as a dozen people?

OF COURSE NOT!

Then the same concept applies to moles.

1 mole CO2, carbon dioxide, does not have the same mass as 1 mole Pb(NO3)4, Lead(IV) Nitrate

WHY? Simply because 1 CO2 molecule has less mass than 1 molecule of Pb(NO3)4. Therefore 6.02 x1023 CO2 molecules (1mole) will obviously have less mass than 6.02 x1023 Pb(NO3)4 molecules (1mole) .

Molecular Weight and Molar Mass

Molecular Weight (A.K.A. Formula Weight for ionic compounds) and Molar Mass are calculated the same way, the only difference is the unit and meaning.

Molecular Weight is the weight of a molecule measured in amu.

Molar Mass is the mass (in grams) of one mole of a substance.

Calculating Molecular Weight and Molar Mass

Example:Calculate the molecular weight of Pb(NO3)2.

Element Atomic mass # of each atom Total

Grand Total

=X

Therefore the molecular weight is 331.22 amu, therefore the molar mass or 331.22 g/mol. (Same # different unit and meaning)

Pb

N

O

207.20

14.01

16.00

1

2

6

207.20

28.02

96.00

331.22 amu

Mole Conversions

Converting between moles, grams and # of particles (atoms, molecules or ions.)

Use Dimensional Analysis

Given Quantityand Unit X

ConversionFactor(s) = Desired Quantity

And Unit

The Concept Map for Mole Conversions

moles

# of Particles(Atoms, molecules)

Mass(grams)

Molar Mass

Avogadros #

# atoms

Ratio of atoms to 1 molecule

Depends on whether the smallest unit of the substance is a molecule or an atom.

# grams = 1 mole

1 mole = 6.02 E23 “things”

Examples

POH g 98.00

POH mol 1

43

43

1) How many moles of H3PO4 are in 9.204 g H3PO4?

2) Calculate the mass of 0.109 mol of Fe(OH)3.

9.204 g H3PO4 0.09392 mol H3PO4X

0.109 mol Fe(OH)3

X 11.6 g Fe(OH)3

Fe(OH) mol 1

Fe(OH) g 106.88

3

3

More Examples

OH mol 1

molec OH E 6.02

2

223

)Pb(SO mol 1

molec )Pb(SO 6.02E

24

2423

3) How many particles are in 50.90 mol H2O? What kind of particles are they (desired unit)?

4) How many oxygen atoms are there in 5.60 mol of Pb(SO4)2?

MOLECULES

50.90 mol H2O X

X

3.064 E25 H2O molecules

5.60 mol Pb(SO4)2

X molec )Pb(SO 1

atomsOxygen 8

24

2.70 E25 Oxygen atoms

More Examples

OH g 18.02

OH mol 1

2

2

OH mol 1

OH molec 6.02E

2

223

223

2

Br molec E 6.02

Br mol 1

5) How many molecules of H2O are in 603.8 g H2O?

6) What is the mass of 9.08E24 Br2 molecules ?

603.8 g H2O

9.08E24 Br2 molec

2

2

Br mol 1

Br g 159.80X

=XX

2.017 E25 molec H2O

X =

2.41 E3 g Br2

Valence Electrons

• Valence electrons are the electrons in the outermost energy shell, or valence shell.

• For representative elements (groups 1-2 and 13-18) the group # will help you determine how many valence electrons an atom has.

The Octet Rule

• The representative elements, when forming ions, will attempt to have 8 electrons in their outer shell.

• Atoms will either lose or gain electrons to result in a completed outer shell.(8 electrons)

Valence ElectronsThe Group # (for the representative elements only) indicates the number of valence electrons.

For example all elements in Group 1 have 1 valence electron. Therefore, they can either gain 7 electron or lose 1 electron to result with a completed valence shell.

Obviously it will require less energy to lose 1 than to try to gain 7, therefore all Group 1 metals become a +1 cation as a result of losing 1 electron.

Common Ion Formation (most representative elements)

•Group 17 needs to gain 1 electron becoming a -1anion.

•Group 16 needs to gain 2 electrons becoming a -2anion.

•Group 15 (non-metals only) needs to gain 3 electrons becoming a -3anion.

•Group 14 (non-metals only) can either gain 4 or lose 4 electrons therefore can form +4 cations or -4 anions.

•Group 13 (non-metals only) needs to lose 3 electrons becoming a +3cation.

•Group 1 needs to lose 1 electron becoming a +1cation.

•Group 2 needs to lose 2 electrons becoming a +2cation.

Common Ion Formation (transition metals)

• All metals form cations.

• Transitions metals can form multiple charges depending upon the situation.

• The most common charges (listed with the

most common first) are the little numbers to the right of the element symbol on your Periodic Table.

Examples

Write the symbol for the most common charge if the following atoms were to become ions.

Na

S

Cr

Sn

Br

Sr

Al

Na+1

S-2

Cr+6

Sn+4

Br-1

Sr+2

Al+3