This document discusses the history and development of the periodic table. It describes how early scientists like Lavoisier and Newlands made early attempts to organize the elements. Mendeleev is credited with developing the first recognizable periodic table in 1869 by arranging elements by atomic mass, though inconsistencies remained until Moseley introduced the concept of atomic number in 1913. The periodic law states that physical and chemical properties are periodic functions of atomic number. Periodic trends like atomic radius are also discussed, with atomic radius decreasing across periods and increasing down groups. The document outlines the different blocks and groups that make up the modern periodic table.

1. Periodic Law

2. Objectives
1. History of the Periodic table
2. Start talking about Periodic trends
3. Periodic Table Geography … families of
elements

3. 1790 Antoine Lavoisier – Compiled a list of
known elements – 23
1864 John Newlands – 1st proposed
organizational scheme for elements

4. Dmitri Mendeleev – Russian
Chemist who first developed
the Periodic Table.

5. Mendeleev’s Periodic Table –
elements are arranged according
to increasing atomic mass
1st Draft
Version of
Mendeleev’s
table

6. In 1913 Henry Moseley conducted
X-ray experiments on elements.
The outcome of his work was the
introduction of the atomic number.
It was found that if Mendeleev's table was
ordered by atomic number instead of
atomic mass the inconsistencies in the
table were eliminated.
This is the blueprint for the modern
periodic table.

7. Periodic Law – The
physical and chemical
properties of the
elements are periodic
functions of their
atomic numbers.

8. Periodic Trends
Atomic Radii –The
size of an atom –
one half the
distance between
the nuclei of two
identical atoms
bonded together

9. Atomic Radii
• Decreases as you go across a period due to
the added positive charge to the nucleus.
• Increases down a group due to the “shielding
effect” caused by the addition of new energy
levels. The inner energy levels act in a way to
shield the attractive charges of the nucleus for
the outer electrons.

10. Periodic Table
Geography

11. The horizontal rows of the periodic table
are called PERIODS.

12. The elements in any group
of the periodic table have
similar physical and chemical
properties!
The vertical columns of the periodic table
are called GROUPS, or FAMILIES.

13. Alkali Metals

14. Alkaline Earth Metals

15. Transition Metals

16. These elements are also
called the rare-earth
elements.
InnerTransition Metals

17. Halogens

18. Noble Gases

19. S block P block
D block
F block

20. Group Properties of Some Main
Group Elements
Alkali metals Alkaline Earth Metals
Halogens Halogens 2
Noble Gases
Braniac Alkali Metals