2.  The arrangement of electrons in an atom helps determine the properties and behavior of that atom

3.  Electrons live in something called energy levels.  Only so many electrons can be in any energy level.  The electrons in the outer most energy level of any element are called valance electrons.

4. Nucleus 1 st energy level 2 nd energy level 3 rd energy level Can hold up to 8 electrons Can hold up to 2 electrons Contains protons & neutrons

6. Ionization Energy Energy needed to remove one of atom’s electrons from its outermost shell Atoms with high ionization energies hold onto their electrons very tightly. Atoms with low ionization energies are more likely to lose one or more of their outermost electron.

7. Hydrogen Helium The value for helium is higher than hydrogen because there are now two protons in the nucleus. The charge is greater so the pull on the outer electrons is stronger. 1310 kJ/mol 2370 kJ/mol Ionization Energy

8. Hydrogen Helium Lithium FURTHER AWAYFURTHER AWAY from the nucleus = less attraction for an electron 519 kJ/mol 1310 kJ/mol2370 kJ/mol Ionization Energy Lithium atoms have 3 protons so you would expect the pull on electrons to be greater. However, the Ionization Energy of lithium is lower than that of helium because…

9. Value decreases down the Group the outer electrons are easier to remove because of the greater distance from the nucleus 519 kJ/mol Li 494 kJ/mol 418 kJ/mol Na K Ionization Energy

10. Electronegativity is a chemical property that describes the tendency of an atom to attract electrons towards itself.

11. An atom's electronegativity is affected by its atomic number. the higher the electronegativity number, the more an element attracts electrons towards itself E LECTRONEGATIVITY

12. Pauling’s electronegativity scale Fluorine is the most electronegative element It has an electronegativity value of 4.0 E LECTRONEGATIVITY