1. THE PERIODIC TABLE
Dmitri Mendeleev ( )

2. THE PERIODIC TABLE Dmitri Mendeleev (1834-1907)
put elements in columns in order of increasing atomic mass
arranged columns so elements with similar prop’s were side by side

3. THE PERIODIC TABLE
left blank spaces where there were no known elements with the appropriate properties or mass.
predicted the properties of the missing elements

4. THE PERIODIC TABLE
Henry Mosely ( )

5. THE PERIODIC TABLE Henry Mosely (1887-1915)
Determined atomic numbers of the elements.
Arranged elements in table by atomic number instead of mass.

7. HORIZONTAL ROWS: PERIODS
seven periods
2 to 32 elements in a period
properties of the elements change
as you move across a period
this pattern repeats from period to
period: The Periodic Law

8. VERTICAL COLUMNS: GROUPS/FAMILIES
Elements in a group have similar physical and chemical properties.
Groups identified by A or B and a #
Group A are the representative elements
Group A can be divided into three broad classes

9. 1. METALS high electrical conductivity high luster when clean ductile
malleable

10. 1. METALS divided into: alkali metals – group 1A
alkaline earth metals – group 2A
transition metals – group B
inner transition metals

11. 2. NONMETALS poor electrical conductivity non-lustrous
group 7A – halogens
group 8A – noble gases

12. 3. METALLOIDS
properties are intermediate between metals and nonmetals