1. Ch. 14: Chemical Periodicity
Standard: Matter consists of atoms that have internal structures that dictate their chemical and physical behavior.
Targets:
Describe the arrangement of elements in the periodic table in order of increasing atomic number.
Distinguish between the terms group and period.
Apply the relationship between the electron arrangement of elements and their position in the periodic table.
Apply the relationship between the number of electrons in the highest occupied energy level for an element and its position in the periodic table.
Discuss the similarities and differences in the chemical properties of elements in the same group.
Describe and explain the group and periodic trends in atomic radii, first ionization energies and electronegativities.

2. Development of the Periodic Table
Describe the arrangement of elements in the periodic table in order of increasing atomic number.
Development of the Periodic Table
Johan Dobereiner
Grouped similar elements into groups of 3 (triads) such as chlorine, bromine, and iodine. ( ).
John Newlands
Found every eighth element (arranged by atomic weight) showed similar properties. Law of Octaves (1863).
Dmitri Mendeleev
Arranged elements by similar properties but left blanks for undiscovered elements (1869).

3. Development of the Periodic Table
Describe the arrangement of elements in the periodic table in order of increasing atomic number. Distinguish between the terms group and period.
Development of the Periodic Table
Henry Mosley
Arranged the elements by increasing atomic number instead of mass (1913)
Glen Seaborg
Discovered the transuranium elements (93-102) and added the actinide and lanthanide series (1945)
Elements are arranged by increasing
atomic number into periods (rows)
and groups or families (columns)

4. Arrangement of the Periodic Table
Describe the arrangement of elements in the periodic table in order of increasing atomic number.
Arrangement of the Periodic Table
Metals
Left side of the periodic table (except hydrogen).
High electrical conductivity, high luster, ductile, malleable
Alkali metals: Group 1
Alkaline earth metals: Group 2
Transition metals: Group 3-12, lanthanide & actinide series

5. Arrangement of the Periodic Table
Describe the arrangement of elements in the periodic table in order of increasing atomic number.
Arrangement of the Periodic Table
Nonmetals
Right side of the periodic table
Poor conductors, nonlustrous, nonmalleable, dull
Halogens: Group 17
Noble gases: Group 18

6. Arrangement of the Periodic Table
Describe the arrangement of elements in the periodic table in order of increasing atomic number.
Arrangement of the Periodic Table
Metalloids
Between metals and nonmetals
Properties intermediate between metals and nonmetals

7. Arrangement of the Periodic Table: pg 392-393
Apply the relationship between the electron arrangement of elements and their position in the periodic table.
Arrangement of the Periodic Table: pg
Noble Gases: Outermost s and p sublevels are filled. Group 18
Ending configuration is s2p6 (except He)
Eight valence electrons (except He)
Row number equals highest energy level
See Figure 14.5 pg 395
Pg 396: practice 1,2; Pg 396: 3,4,5

8. Arrangement of the Periodic Table: pg 392-393
Apply the relationship between the electron arrangement of elements and their position in the periodic table.
Arrangement of the Periodic Table: pg
Representative Elements: Outermost s and p sublevels are partially filled.
Group 1-2 and 13-18
1 (s1); 2 (s2); 13 (s2p1); 14 (s2p2)…
Group number equals valence electrons
Row number equals highest energy level
Transition Metals
Filling the d & f sublevels
Go to Chemistry: periodicty Trends Practice 1
See Figure 14.5 pg 395
Pg 396: practice 1,2; Pg 396: 3,4,5

9. Shortcut Electron Configuration
Apply the relationship between the electron arrangement of elements and their position in the periodic table.
Shortcut Electron Configuration
Based on the electron configuration of the noble gases.
He ends in 1s2; Ne ends in 2p6; Ar ends in 3p6; Kr ends in 4p6; etc.
Write the electron configuration and orbital filling diagram for Se
Se has 34 electrons
Go back to the previous noble gas: Ar (18 electrons). Begin the configuration with [Ar] which accounts for 18 electrons and then begin with 4s2. Continue until you reach 34 electrons
[Ar]4s23d104p4
[Ar] __ __ __ __ __ __ __ __ __
4s d p

10. GO TO NOBLE GAS CONFIGURATION PRACTICE Handout
Apply the relationship between the electron arrangement of elements and their position in the periodic table.
Shortcut Electron Configuration
Write the electron configuration and orbital filling diagram for Au
Au has 79 electrons
Go back to the previous noble gas: Xe (54 electrons). Begin the configuration with [Xe] which accounts for 54 electrons and then begin with 6s2. Continue until you reach 79 electrons
[Xe]6s24f145d9
[Xe] __ __ __ __ __ __ __ __ __ __ __ __ __
6s f d
GO TO NOBLE GAS CONFIGURATION PRACTICE Handout

11. Shortcut Electron Configuration
Apply the relationship between the number of electrons in the highest occupied energy level for an element and its position in the periodic table.
Shortcut Electron Configuration
Electron dot diagrams
Group 1: 1 dot X Group 15: 5 dots X
Group 2: 2 dots X Group 16: 6 dots X
Group 13: 3 dots X Group 17: 7 dots X
Group 14: 4 dots X Group 18: 8 dots (except He) X
GO TO WHITE BOARD LEWIS DOT PRACTICE and Noble gas configuration practice.

12. Trends in the Periodic Table
GO TO PERIOD TRENDS GRAPH ACTIVITY
GO TO REACTIVITY LAB

13. Periodic Trend Definitions
Atomic Radius: half the internuclear distance between two atoms of the same element (pm)

14. Periodic Trend Definitions
Electronegativity: a measure of the tendency of an atom in a molecule to attract a pair of shared electrons towards itself

15. trends are easier to understand if you comprehend the following
the ability of an atom to “hang on to” or attract its valence electrons is the result of two opposing forces
the attraction between the electron and the nucleus
the repulsions between the electron in question and all the other electrons in the atom (often referred to the shielding effect)
the net resulting force of these two is referred to effective nuclear charge

16. This is a simple, yet very good picture. Do you understand it?

17. 3.2.2 Describe and explain the trends in atomic radii, ionic radii, first ionization energies, electronegativities and melting points
Atomic Radii
The radius of an atom, measured in pm (picometers)
Periodic trend (Period 3 Trend)
Atomic size decreases as you move across a period.
The increase in nuclear charge increases the attraction to the outer shell so the outer energy level progressively becomes closer to the nucleus
Group trend for Alkali metals & Halogens
Atomic size increases as you move down a group of the periodic table.
Adding higher energy levels

19. Atomic Radii

21. 3.2.2 Describe and explain the trends in atomic radii, electronegativity's and reactivity.
Tendency for the atoms of the element to attract electrons when they
are chemically combined with atoms of another element.
Helps predict the type of bonding (ionic/covalent).
Periodic Trend (Period 3 Trend)
Increases as you move from left to right across a period.
Nonmetals have a greater attraction for electrons than metals & there is a greater nuclear charge that can attract electrons
Group trend for Alkali metals & Halogens
Generally decreases as you move down a group in the periodic table.
For metals, the lower the inner nuclear force the more reactive.
For nonmetals, the higher the inner nuclear force the more reactive.

22. Electronegativity

23. 3.2.2 Describe and explain the trends in atomic radii, ionic radii, first ionization energies, electronegativities and melting points
Reactivity
The relative capacity of an atom, molecule or radical to undergo a chemical reaction with another atom, molecule or radical.
Don’t worry about the periodic trend!!!
Group trend for Alkali metals
Increases as you move down group 1 in the periodic table
Since alkali metals are more likely to lose an electron, the ones with the lowest inner nuclear force are the most reactive since they require the least amount of energy to lose a valence electron.
Group trend for Halogens
Decreases as you move down group 17 in the periodic table
Since halogens are more likely to gain an electron, the ones with the greatest electronegativity are the most reactive since they are most effective at gaining a valence electron.

24. Discuss the similarities and differences in the chemical properties of elements in the same group.
Group 1: Alkali Metals
Have 1 valence electron
Shiny, silvery, soft metals
React with water & halogens
Oxidize easily (lose electrons)
Reactivity increases down the group
Group 17: Halogens
Have 7 valence electrons
Colored gas (F2, Cl2); liquid (Br2);
Solid (I2)
Oxidizer (gain electrons)
Reactivity decreases down the group