Chapter 8The Periodic Table

What is the Periodic Table good for?

The Periodic Table Symbols and names Protons, electrons, &

neutrons Atomic mass Size of atoms & ions Strength of ions

(electronegativity) Electron configuration

Atomic SizeHow is atomic size determined?

The electron cloud doesn’t have a definite edge.

Atomic Size

Atomic Radius = half the distance between two nuclei of a diatomic molecule.

}Radius

Trends in Atomic Size Influenced by two factors:1. Energy Level

- Higher energy level is further away.

2. Charge on nucleus- More charge pulls electrons

in closer.

Group trends

Increasing number of energy levels

HLi

Na

K

Rb

Periodic Trends As you go across a period the

radius gets smaller. Same energy level. More nuclear charge.

Na Mg Al Si P S Cl Ar

Ionic Size Cations formed by losing electrons.

Metals form cations. Cations of representative elements have noble gas configuration.

Ionic size Anions form by gaining electrons.

Nonmetals form anions. Anions of representative elements have noble gas configuration.

Group trends

Increasing number of energy levels

Li+1

Na+1

K+1

Rb+1

Cs+1

Periodic Trends

Energy level changes between anions and cations.

Li+1

Be+2

B+3

C+4

N-3 O-2 F-1

Electronegativity

The tendency for an atom to attract electrons to itself when it is in a compound

Group Trend The further down a group, the farther the electron from the nucleus

More willing to share. Lower electronegativity.

Periodic TrendMetals are at the left end

•Metals lose electrons•Low electronegativity

At the right end are the nonmetals.•Nonmetals gain electrons•High electronegativity.

Electron ConfigurationAtomic Orbitals fill up in a

regular pattern.

The outside orbital electron configuration repeats.

Therefore, the properties of atoms repeat.

1s1

1s22s1

1s22s22p63s1

1s22s22p63s23p64s1

1s22s22p63s23p64s23d104p65s1

1s22s22p63s23p64s23d104p65s24d10

5p66s1

1s22s22p63s23p64s23d104p65s24d10

5p66s24f145d106p67s1

H1

Li3

Na11

K19

Rb37

Cs55

Fr87

He2

Ne10

Ar18

Kr36

Xe54

Rn86

1s2

1s22s22p6

1s22s22p63s23p6

1s22s22p63s23p64s23d104p6

1s22s22p63s23p64s23d104p65s24d105p6

1s22s22p63s23p64s23d104p65s24d10

5p66s24f145d106p6

Alkali metals all end in s1

Alkaline earth metals all end in s2

Helium included is S - block

s2s1 S- block

Transition Metals -d block

d1 d2 d3s1

d5 d5 d6 d7 d8s1

d10 d10

The P-block

p1 p2 p3 p4 p5 p6

F - block inner transition elements

f1 f5f2 f3 f4

f6 f7 f8 f9 f10 f11 f12 f14

f13

Each row (or period) is the energy level for s and p orbitals.

1

2

3

4

5

6

7

D orbitals fill up after previous energy level

1

2

3

4

5

6

7

3d

f orbitals start filling at 4f

1

2

3

4

5

6

7 4f

5f

Writing Electron Configurations the Easy

Way

Electron Configurations Repeat

As you move across a period, the outermost energy level is filled

This is the basis for writing shorthand electron configurations.

The Shorthand

Aluminum 1s22s22p63s23p1

Ne is 1s22s22p6

so Al is [Ne] 3s23p1

The Shorthand Again

Sn- 50 electrons

The noble gas before it is Kr

[ Kr ]

Takes care of 36

Next 5s2

5s2

Then 4d10

4d10Finally 5p2

5p2