The Periodic Table

1. The Periodic Table

2. Development of Periodic Table • Dmitri Mendeleev (1834-1907) • The first person to arrange the elements into a logical order • Arranged elements in order of increasing atomic mass and then organized them according to similar properties

3. Development of Periodic Table

4. Development of Periodic Table • Henry Moseley (1887-1915) • Discovered atomic number • Arranged the elements in order by atomic number instead of by atomic mass • Current format of the periodic table

5. Periodic Table • Groups: columns (up and down) • Elements in the same group have similar properties • Periods (or families): rows

6. Periodic Table • Metal • Transition metals • Alkali • Alkali earth • Nonmetal • Halogens • Noble gases • Metalloids

7. Periodic Table • Metal • Characteristically lustrous, malleable, ductile, and good conductors of heat and electricity • Nonmetal • Not lustrous and generally poor conductors of heat and electricity • Metalloids • Has properties intermediate to both metals and nonmetals

8. Organization nonmetals metals • noble gases • metalloids • halogens • alkali earth alkali • transition metals • lanthinides • actinides

9. Valence electrons • Electron in the outermostenergy level of an atom • 1st shell has 2 • 2nd shell and up generally have 8 • Can use the periodic table to easily predict the number of valence electrons

10. Atomic Radii • Generally decreases as you travel left to right across a period and increases as you travel from top to bottom • Why?

11. Electronegativity • measure of the tendency of an atom to attract a bonding pair of electrons. • Increases as you move across left to right and from bottom to top

12. Electron Affinity • The amount of energy required to remove an electron from an element • Generally increases from left to right and bottom to top