Chapter 8 The Periodic Table

What is the Periodic Table good for?

The Periodic Table u Symbols and names u Protons, electrons, & neutrons u Atomic mass u Size of atoms & ions u Strength of ions (electronegativity) u Electron configuration

Atomic Size u How is atomic size determined? u The electron cloud doesn’t have a definite edge.

Atomic Size u 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 H Li Na K Rb

Periodic Trends u As you go across a period the radius gets smaller. u Same energy level. u More nuclear charge. NaMgAlSiPSClAr

Ionic Size u Cations formed by losing electrons. u Metals form cations. u Cations of representative elements have noble gas configuration.

Ionic size u Anions form by gaining electrons. u Nonmetals form anions. u 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 u The tendency for an atom to attract electrons to itself when it is in a compound

Group Trend u The further down a group, the farther the electron from the nucleus u More willing to share. u Lower electronegativity.

Periodic Trend Metals are at the left end Metals lose electrons Low electronegativity At the right end are the nonmetals. Nonmetals gain electrons High electronegativity.

Electron Configuration Atomic Orbitals fill up in a regular pattern. The outside orbital electron configuration repeats. Therefore, the properties of atoms repeat.

1s11s1 1s 2 2s 1 1s 2 2s 2 2p 6 3s 1 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 1 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 1 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 7s 1 H 1 Li 3 Na 11 K 19 Rb 37 Cs 55 Fr 87

He 2 Ne 10 Ar 18 Kr 36 Xe 54 Rn 86 1s21s2 1s 2 2s 2 2p 6 1s 2 2s 2 2p 6 3s 2 3p 6 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6

u Alkali metals all end in s 1 u Alkaline earth metals all end in s 2 u Helium included is S - block s2s2 s1s1 S- block

Transition Metals -d block d1d1 d2d2 d3d3 s1d5s1d5 d5d5 d6d6 d7d7 d8d8 s 1 d 10 d 10

The P- block p1p1 p2p2 p3p3 p4p4 p5p5 p6p6

F - block u inner transition elements

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

u D orbitals fill up after previous energy level d

u f orbitals start filling at 4f f 5f

Writing Electron Configurations the Easy Way

Electron Configurations Repeat u As you move across a period, the outermost energy level is filled u This is the basis for writing shorthand electron configurations.

The Shorthand Aluminum 1s 2 2s 2 2p 6 3s 2 3p 1 u Ne is 1s 2 2s 2 2p 6 u so Al is [Ne] 3s 2 3p 1

The Shorthand Again Sn- 50 electrons The noble gas before it is Kr [ Kr ] Takes care of 36 Next 5s 2 5s 2 Then 4d 10 4d 10 Finally 5p 2 5p 2