1. Chapter 5
In a nutshell

2. Key Players
Dmitri Mendeleev- father of periodic table; arranged elements in order of increasing atomic mass.
Henry Mosley- creator of the MODERN periodic table; arranged elements in order of increasing atomic numbers (# of protons in nucleus)

3. Vocabulary
Periodic law- the physical and chemical properties of the elements are periodic functions of their atomic numbers.
Or… when the elements are arranged in order of increasing atomic number elements with similar properties appear at regular intervals.
Periodic Table- an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column, or group.

4. Noble gasses
Group 18
Non reactive
All gasses
8 valence electrons

5. Section 2

6. Periods How many energy levels does Lithium (3) have? 2
How many energy levels does Arsenic (33) have? 4
How many energy levels does Radium (88) have? 7

7. Blocks
S block
P block
D block
F block

8. S Block elements Group one = alkali metals
Soft; silvery appearance; VERY reactive; not found in nature except in compounds
React vigorously with water to produce hydrogen gas and aqueous solutions of alkalis
Group two = alkaline-earth metals
Harder denser and stronger than alkali metals
Higher melting points than alkali metals
Less reactive than alkali metals but are still not found in nature unless in compounds

9. Hydrogen and Helium Hydrogen and helium are exceptions to many rules.
Know their electron configurations and learn when they apply to the rules and when they don’t.

10. Practice 3s^1 Na (11) 2p^3 N (7) 6d^4 W (74) 5p^2 Sn (50) 3d^6 Fe (26)
Ca (20)
1s^2
He (2)
5d^9
Ag (47)
6p^2
Pb (82)
3p^5
Cl (17)

11. D-block Elements Transition elements
Elements with typical metallic properties
Good conductors of electricity
Have high luster
Typically less reactive than s-block elements.
Some are so unreactive that some can stand alone in nature (palladium, platinum, and gold)

12. P-block elements
Consists of all the elements of groups except helium.
P block elements with the s-block elements are called the main-group elements or representative elements.
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13. F-block
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14. Quiz Creator of the modern periodic table?
React vigorously with water to produce hydrogen gas and aqueous solutions of alkalis
Some are so unreactive that some can stand alone in nature (palladium, platinum, and gold)
5d^9
Consists of all the elements of groups except helium
Mosley
Alkali Metals
Transition metals or d-block elements
Silver (Ag)
p-block elements

15. Section 3
Electron configuration and periodic properties.

16. Atomic radii
You would think that the atomic radii would be measured from the center of the nucleous to the outer edge of the electron cloud.
But the electron cloud edge is fuzzy and indistinct, so it’s hard to find an accurate measurement. So
Atomic Radius- one-half the distance between the nucei of identical atoms that are bonded together.

17. Period trends
There is a gradual decrease in atomic radii across the second period from lithium to neon.
This is caused by the increasing positive charge of the nucleous.
The increased pull on the electrons results in the decrease in atomic radii.
As you move down a group, the atomic radii tend to increase.
This is because of more energy levels

18. Ionization energy
An electron can be removed from an atom if enough energy is supplied.
A + energy  (A+) + e-
A = atom…… A+ = an ion of an element with a single positive charge. (a 1+ ion)
Ion- an atom or group of bonded atoms that has a positive or negative charge.
Ionization- any process that results in the formation of an ion.

19. Ionization energy- the energy required to remove one electron from a neutral atom of an element.
IE or first ionization energy (IE1)
Period trends:
IN GENERAL ionization energies of the main group elements increase across each period.
Group trends:
Ionization generally decrease as you move down a group.
This is why elements tend to be more reactive as you move down the table.

20. Electron Affinity
Electron Affinity- the energy that occurs when an electron is acquired by a neutral atom.
most atoms release energy when they acquire an electron.
A + e-  (A-) + energy … the quantity of energy released is expressed as a negative number
Some atoms must be forced to gain an electron by the addition of energy.
A + e- + energy  A- … the quantity of energy absorbed is represented as a positive number.

21. Period trends
In general, electron affinities become more negative across the p-block.
With the exception of groups 14 and 15.
Group Trends
Group trends of electron affinities are not as regular as many other characteristics.

22. Electronegativity
Valence electrons hold atoms together in chem compounds.
In many compounds the negative charge of the valence electrons is concentrated closer to one atom than the other.
Electronegativity- a measure of the ability of an atom in a chemical compound to attract electrons.
The most elecronegative element, flourine, is arbitrarily assigned an electronegativity value of four. The values of the other elements are calculated in realtion to this value.

23. Period Trends
Electronegativites tend to increase across each period, although there are exceptions.
Alkali and alkaline-earth metals are the least electronegative elements.
Nitrogen, oxygen, and the halogens are the most electronegative elements.
Group trends
Electronegativities tend to either decrease down a group or stay about the same.

24. Quiz For a Test Grade
one-half the distance between the nucei of identical atoms that are bonded together.
As you move down a group, the atomic radii tend to_________
any process that results in the formation of an ion is called ________
ionization energy is abbreviated _______
the energy that occurs when an electron is acquired by a neutral atom is called electron ______
Atomic radius
Increase
Ionization IE
Affinity