1. Mendeleev’s Periodic Table (1869)

2. Periodic Law
Moseley arranged the periodic table by increasing atomic number.
When Elements are arranged in order of increasing atomic number, there is a periodic repetition of physical and chemical properties.

3. Metals, Nonmetals, and Metalloids

4. Squares in the Periodic Table

5. Representative Elements
Groups 1A through 7A
s and p sublevels of the highest occupied energy levels are not filled
Groups include:
Alkali metals
Alkaline-earth metals
Halogens

6. Noble Gases Group 8A Inert gases that rarely take part in reactions
s and p sublevels are full

7. Transition Elements Transition metals Inner transition metals
Valance electrons in s and d sublevels
Inner transition metals
Valance elections in s and f sublevels

8. Electron Configuration
Energy level for d = row –1
Energy level for f = row – 2

9. Trends in Atomic Size
Atomic radius – ½ distance between the nuclei of two atoms of the same element when the atoms are joined
Size increase down a group because there are more energy levels
Size decrease down a period because the positive nucleus pulls the increased negative charge of the electrons closer

10. Trends in Atomic Size

11. Ions Charged atoms Cations – have lost electrons
Anions – have gained electrons
Ionization Energy – is the energy required to remove an electron from an atom
1st ionization energy is the amount required to remove the first electron from an atom
2nd ionization energy is the amount required to remove an electron from a +1 ion

12. What does the blue line on the chart mean? (think energy levels)

13. Trends in Ionization Energy
Ionization energy decrease down a group because the valence electrons are further from the nucleus.
Ionization energy increases down a period because the nuclear charge and the charge of outer energy level increases across the period, while the shielding effect remains constant.

14. Trends in Ionic Size Cations are smaller than their atoms
Anions are larger than their atoms.

15. Trends in Ionic Size

16. Trends in Electronegativity
Electronegativity – is the ability of an atom to attract electrons in a bond
Increases from left to right
Decreases down a column
Fluorine is the most electronegative element at 4.0

17. Summary of Trends