The Periodic Law – Chapter 5

What does the word “periodic” mean?

• Periodic:

Mendeleev 1869

• Arranged elements according to _______________________

• Put elements of similar properties in the same_______________________

• Why did he leave blank spots in table?

2 questions …..

1. Why could most elements be arranged in order of increasing atomic mass but a few could not? (Te & I, Co & Ni, Ar & K)

2. What was the REASON for chemical periodicity?

Henry Mosley1911 (40+ years later)…

• Used X-ray and spectral studies to show that each element has ________________

• ___________________ is a better basis for organizing the Periodic Table

Periodic Law

• The physical and chemical properties of the elements are periodic functions of their___________

Modern Periodic Table

• An arrangement of the elements in order of their______________

so that elements with similar properties fall in the same___________,

or _____________

Noble Gases

• Proposed by Sir William Ramsay and John William Strutt

• Lack of chemical ______________

The Lanthanides

• The 14 elements with atomic numbers from 58(cerium, Ce) to 71(lutetium, Lr)

• Similar in__________ and___________ properties

The Actinides

• The 14 elements with atomic number from 90(thorium, Th) to 103(lawrencium, Lr)

Periodicity

• Figure 5-4 on page 126

• Periodicity is explained by the arrangement of the________________around the nucleus

5-2Electron Configuration and

The Periodic Table

What is the outer configuration of the following:

• Re (#75)

• I (#53)

• Cd (#48)

Which sublevel fills in after the…

• 4s

• 4d

• 6s

• 5p

5-3Electron Configurations and

Periodic Properties

Atomic Radius• One-half the distance between the nuclei

of identical atoms that are bonded together

Group Trend for Atomic Radii

• Down a group the radius of an atom gets ……..…. because…

Period Trend for Atomic Radii

• Across a period the radius of an atom gets ………………....because….

• Exception: Noble Gas Family – atoms don’t interact and pull together like in other atoms because__

Why does the atomic radii not decrease very much as you move

across the d-sublevel?

Why would the atomic radius of hafnium (#72) be LESS than that

of zirconium (#40)?

Ionization energy, IE

• Energy required to _________ an electron from a neutral atom (or first ionization energy, IE1)

• __________: charged particle• _______________: process of an electron

being lost or gained from an atom which results in the formation of an ion

Group Trend for Ionization Energies

• Down a group the ionization energy of an atom generally gets …………………

because….

Period Trend for Ionization Energies

• Across a period the ionization energy …….…..because

4 Factors Affecting Ionization Energy

Multiple Ionization Energies• Energy required to remove the 2nd, 3rd, etc.

electron from an atom

• IE3……. IE2….. IE1 because ………

Why does the IE go UP as you go down a d-sublevel group but go

down in an s sublevel?

Electron Affinity p. 147• Energy change the occurs when an __________________________ by a neutral atom

• Most atoms _______ energy when they acquire an electron: A + e- A- + energy– energy has _____sign

• Some atoms ________ energy when they acquire an electron: A + e- + energy A-

– energy has ______ sign; atom is unstable & loses electron spontaneously

Group Trend for Electron Affinities

• Down a group the electron affinity of an atom tends to get …………….because

Period Trend for Electron Affinity• Across the p-sublevel, the energy change

………………(becomes more …………..)

because…..

Why is the electron affinity of nitrogen so low when compared

to carbon or oxygen?

Multiple Electron Affinities

• It is always ……………….. to add a 2nd electron to an already negatively charged ion..therefore, all 2nd electron affinities are …………………..

Ionic Radii• Cation:

• _________ ion

• Formed by an atom …………. electron(s)

• Always …………. because electron cloud is smaller (less repulsion) & sometimes even one less energy level!

• Anion:

• __________ ion

• Formed by an atom …………… electron(s)

• Always …………. because electron cloud is greater (more repulsion among electrons)

Group Trend for Ionic Radii

• Down a group the ionic radius of an atom generally gets ……………because

.

Period Trend for Ionic Radii• Metals (left side):form …………….

– Cationic Radius: ………….. ionic radius as nuclear charge increases without adding an energy level

• Non-metals: form ………………

– Anionic Radius:……………………. ionic radius as nuclear charge increases without adding an energy level

Valence Electrons

• Electrons available to be lost, gained, or shared in the formation of chemical compounds

• Often the outermost electrons because they are held most loosely

What would be the # of valence electrons in……..

• Calcium

• Lithium

• Chlorine

• carbon

What would be the # of valence electrons in……..

• Calcium – 2 : 4s2

• Lithium – 1: 2s1

• Chlorine – 7: 3s23p5

• Carbon – 4: 2s22p2

Electronegativity

• Measure of the ability of an atom ______

___________________to attract electrons

• ___________________ is the MOST electronegative element – assigned an arbitrary value of ______

• All other values are relative to F

• 3 highest values: F – O - N

Group Trend for Electronegativity

• Tend to ___________ down a group (or stay the same) as the atoms gets larger

Period Trend for Electronegativity

• Tend to _______________ across the period as the atoms gets ________, the nuclear charge becomes ___________, and the atom is getting closer to a noble gas configuration

Determine the likely charge for the following elements: Ca, O, Al

1. Write the noble gas configuration of the element

2. Determine if electrons will be LOST or GAINED to make the element stable

3. ID the noble gas whose electron configuration by losing/gaining these electrons

4. Write the formula for the ion

5. ID it as a cation anion

How do d-block elements form ions?

• Electrons in the highest occupied sublevel are always removed first

Why does zinc become a +2 ion?

Which electrons are lost when titanium becomes a +2, a +3 and a +4 ion?