1. and Electronegativity
Atomic size
and Electronegativity

2. Definitions Atomic radius
a measurement of the relative length of an atom from its nucleus to its outermost orbital

3. Atomic radius increases
Atomic radius decreases
Huh?!?!

4. Why does the radius get smaller as the number of electrons increases from left to right?
The increased number of protons from left to right pulls the electrons a little closer to the nucleus, causing the overall size of the atom (atomic radius) to decrease a little bit.

5. Then why does the radius get larger as you move down through the periodic table?
As you move from element to element down one period/row, the number of energy levels increases as does the size of the atomic radii!

6. Definitions Ion an atom that has gained or lost one or more electrons
Cation
a positively charged ion
Anion
a negatively charged ion

7. Definitions Ionic radius
Cations = smaller ionic radius than the atoms in which they were created…fewer number of electrons takes up less space
Anions have gained extra electrons which causes their ionic radius to increase

8. Definitions Electronegativity
a measurement of how much an atom can pull electrons away from other atoms

9. To understand this, you must first know something…
Electronegativity decreases
Electronegativity increases
To understand this, you must first know something…

10. All elements on the periodic table want to be like the noble gases.
Why?
Because everything in the universe tends to move towards the lowest energy possible!

11. Why does electronegativity increase from left to right?
Elements on the right side of the periodic table want to gain electrons in order to be like the noble gases
Meanwhile, elements on the left side are trying to give away their electrons to be like noble gases.
Remember… electronegativity is a measurement of how much an atom can pull electrons away from other atoms

12. Why does electronegativity decrease as you move down through the periodic table??
Shielding effect
the inner electrons of an atom act as a shield between the nucleus and the valence electrons which lowers the electronegativity of the atom
Remember… electronegativity is a measurement of how much an atom can pull electrons away from other atoms

13. Pauling’s Electronegativity Scale
You should be writing these down! H
2.1 He - Li
1.0 Be
1.5 B
2.0 C
2.5 N
3.0 O
3.5 F
4.0 Ne Na
0.9 Mg
1.2 Al Si
1.8 P S Cl Ar

14. Every element (except the nobles) have electronegativity