1. Periodic Table
Chapter 6

2. Periodic Table
A chart that organizes all known elements into a grid of horizontal rows, periods, and vertical columns, groups, arranged by increasing atomic number.

3. Development of Modern Periodic Table
Mendeleev, First atomic table, about 63 elements
Organized by atomic mass
Connected atomic mass to properties of elements

4. Medeleev

5. Periodic Law Henry Moseley, atomic number.
Periodic Law: periodic repetition of chemical and physical properties of the elements.

6. Modern Periodic Table Increasing atomic number
Horizontal rows called periods
Vertical columns called groups or families
Main group, representative, elements
Transition Elements

7. Modern Periodic Table
Metals: left side, good conductors, solids usually
Metaloids: Stair step, similar properties of metals and nonmetals
Nonmetals: right side, gases or dull solids, poor conductors

8. Alkali Metals Group 1A – excluding hydrogen
Shiny, malleable, ductile, good conductors
1 valence electron, readily forms +1 cation
Reacts violently with water
Reactivity increases as you go down column.

9. Alkali Earth Metals Group 2A or 2 Ca, Ba, and Sr react with water
2 valence electrons, therefore form +2 cations.

10. Halogens Highly reactive group 7A or 17 Most are gasses
7 valence electrons, from -1 anion easily

11. Noble Gasses
Group 8A or 18
Formally called inert gasses but actually can react, Xe
Full outer energy level

12. Periodic Trends Atomic Radii Increase down family Why?
Decreases down period
Higher effective nuclear charge.

13. Ionization Energy (IE)
Energy required to remove an electron from an atom.
How strongly an atom’s nucleus holds onto its valence electron.
↑ IE, less likely to form positive ions
As you move across period IE increases.
Why?
Increased Charge has stronger hold on electrons

14. Ionization Energy (IE)
As you move down group the IE decreases.
Why?
Electron shielding, further away

15. Octet Rule
States that all atoms tend to gain, lose, or share electrons in order to acquire a full set of eight valence electrons.
Understanding octet rule helps determine ions.
Metals form cations, nonmetals form anions.

16. Electronegativity
Relative ability of the atoms to attract electrons in a chemical bond.
Decreases down groups
Increases across period
Francium least electronegative
Fluorine most electronegative