Presentation on theme: "The Periodic Table How the periodic table is put together."— Presentation transcript:
The Periodic Table How the periodic table is put together
Who created it? In 1869, Russian chemist Dimitri Mendeleev proposed arranging elements by atomic weights and properties. The table contained gaps but Mendeleev predicted the discovery of new elements. The usefulness of table was confirmed with the discovery of the elements that fit the gaps.
So how is it arranged? The elements are placed in specific places because of the way they look and act.
You've got Your Periods... When you look at a periodic table, each of the rows is considered to be a different period
Periods = Rows In the periodic table, elements have something in common if they are in the same row. All of the elements in a period have the same number of atomic orbitals.atomic orbitals Every element in the top row (the first period) has one orbital for its electrons. All of the elements in the second row (the second period) have two orbitals for their electrons and so on.electrons As you move from left to right across the period, the elements become less metallic.
And you got your groups… When a column goes from top to bottom, it's called a group.
Groups = Columns The elements in a group have the same number of electrons in their outer orbital. Every element in the first column (group one) has one electron in its outer shell. Every element on the second column (group two) has two electrons in the outer shell and so on. There are some exceptions to the order when you look at the transition elements.transition elements
Reactivity of elements As you move down the group the reactivity of an element increases. The tendency of an element to react is closely related to the number of valence electrons in atoms of the element. To keep them from reacting, some highly reactive elements are stored in argon (a noble gas). The most reactive elements tend to have one or seven valence electrons.
Other than periods and groups, the table is divided into families. From www.science-class.net
very reactive metals that do not occur freely in nature malleable, ductile, good conductors of heat and electricity. can explode if they are exposed to water Metals can be solids or liquids at room temperature but are never gases. ALKALI METALS **Sodium is only found in nature in compounds and never by itself.
metals very reactive not found free in nature ALKLINE EARTH METALS From www.science-class.net
ductile and malleable, and conduct electricity and heat iron, cobalt, and nickel, are the only elements known to produce a magnetic field. TRANSITION METALS From www.science-class.net
many are man-made RARE EARTH ELEMENTS From www.science-class.net
are ductile and malleable are solid, have a high density, OTHER METALS From www.science-class.net
have properties of both metals and non- metals some of the metalloids are semi- conductors. This means that they can carry an electrical charge under special conditions. This property makes metalloids useful in computers and calculators METALLOIDS From www.science-class.net
not able to conduct electricity or heat very well very brittle Do not reflect light. Carbon is found in your body in most compounds except for water. NON-METALS From www.science-class.net
"halogen" means "salt-former" and compounds containing halogens are called "salts" exist in all three states of matter These are the most reactive nonmetals. HALOGENS From www.science-class.net
do not form compounds easily because they have a full outer shell of electrons Argon and Krypton emit colors when electric current is applied (used in signs).Argon and Krypton emit colors when electric current is applied (used in signs). NOBLE GASES From www.science-class.net