Periodic Law Chapter 6. Objectives 1. History of the Periodic table 2. Start talking about Periodic...
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Transcript of Periodic Law Chapter 6. Objectives 1. History of the Periodic table 2. Start talking about Periodic...
Objectives1. History of the Periodic table2. Start talking about Periodic trends3. Periodic Table Geography … families of elements
1790 Antoine Lavoisier – Compiled a list of known elements – 23
1864 John Newlands – 1st proposed organizational scheme for elements
Mendeleev’s Periodic Table – elements are arranged according to increasing atomic mass
1st Draft Version of Mendeleev’s table
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.
Periodic Law – The physical and chemical properties of the elements are periodic functions of their atomic numbers.
Periodic Trends
Atomic Radii –The size of an atom – one half the distance between the nuclei of two identical atoms bonded together
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.
The vertical columns of the periodic table are called GROUPS, or FAMILIES.
The elements in any group of the periodic table have similar physical and chemical properties!
Alkali metals Alkaline Earth Metals
Braniac Alkali Metals
Halogens Halogens 2
Group Properties of Some Main Group Elements
Noble Gases