The Periodic Table

The Language of Chemistry CHEMICAL ELEMENTS pure substances that cannot be changed into other substances. Aluminum Bromine Sodium

The Language of Chemistry The elements, their names, and symbols are given on the PERIODIC TABLE How many elements are there?

The Periodic Table Dmitri Mendeleev (1834 - 1907)

Dmitri Mendeleev (1869) In 1869 Mendeleev and Lothar Meyer (Germany) published nearly identical classification schemes for elements known to date. Mendeleev gets most credit as he could make accurate predictions about elements which he thought must exist, but were unknown. The Periodic Table is based on the similarity of properties and reactivities exhibited by certain elements. Later, Henri Moseley (England, 1887-1915) established that each elements has a unique atomic number, which is how the current periodic table is organized.

Glenn Seaborg (1912-1999 ) Discovered 8 new elements. Only living person for whom an element was named.

Periods in the Periodic Table The rows are the Periods of the Periodic Table. As you go down the Periodic Table the elements become more reactive.

Groups in the Periodic Table The elements in the columns are the Groups of the Periodic Table. Elements in groups react in similar ways!

Group 1: Alkali Metals Reaction of potassium + H2O Cutting sodium metal

Group 2: Alkaline Earth Metals Magnesium

Group 7: The Halogens Fluorine, Chlorine, Bromine, Iodine

Group 8: The Noble Gases Helium, Neon, Argon, Krypton, Xenon, Radon Lighter than air balloons “Neon” signs Very Unreactive XeOF4

Transition Elements Iron in air gives iron(III) oxide Lanthanides and actinides Iron in air gives iron(III) oxide

Names of Elements Each element is given a separate name Hydrogen, carbon, oxygen, iron and aluminium are some well known elements Several elements, such as curium and einsteinium are named after well known scientists Others such as francium, germanium and americium are named after their country of discovery Names of Elements

Where do all the Chemical Elements come from? Only the first 92 elements occur naturally and can be found in the Earth, air or water. Nuclear scientists have produced these chemical elements inside nuclear reactors Many of these new elements do not last very long and often break down by giving off nuclear radiation.

Atomic Symbols Each element is also given a one letter or two letter symbol which is used as a shorthand way of writing the element Where a one letter symbol is used, it is written in upper case Where two letters are used, the first is written in upper case, and the second in lower case

Atomic Symbols continued… Some element symbols are clearly abbreviations of the elements’ names e.g. carbon – C, oxygen – O, calcium – Ca Others, such as iron – Fe, sodium – Na, mercury – Hg, are abbreviations of their Latin names: ferrum, natrium and hydrargyrum

Atomic Number Each element has a different ATOMIC NUMBER – this is identified at the top of their square 13 Atomic number Al Atom symbol 26.981 AVERAGE Atomic Mass

Abundance of the Elements ABUNDANCE means how much there is of it. There are differences between the abundance of elements in the Universe, the Earth and in the human body. All other elements 3% Hydrogen 60% Helium 37%

All other elements – mainly metals 12% Oxygen 47% Iron 5% Aluminium 8% Silicon 28% Calcium 2% All other elements – mainly metals 2% Nitrogen 2% Hydrogen 10% Oxygen 65% Carbon 18%