THE PERIODIC TABLE By the end of this lesson, you should be able to describe the relationship between the arrangement of elements on the periodic table and the properties of those elements.

THE HISTORY/DEVELOPMENT OF THE PERIODIC TABLE The Periodic Table consist of elements: What are atoms? What are the parts of an atom? Were are they located in the atom? What is the central region of an atom? How does an atom relates to an element? Who was Democritus? Define Atomos?

THE HISTORY/DEVELOPMENT OF THE PERIODIC TABLE An atom is the smallest unit of an element that maintains the properties of that element. The parts of an atom nucleus( center of the atom);(protons(+);neutrons(=), electrons(-). The protons and neutrons are located in the nucleus of an atom. The electrons are located in the electron cloud It is the smallest unit that has the chemical properties of an element. Atoms are the particles which makes up an element.

THE HISTORY/DEVELOPMENT OF THE PERIODIC TABLE In 1869 Russian chemist Dimitri Mendeleev started the development of the periodic table, arranging chemical elements by atomic mass. He predicted the discovery of other elements, and left spaces open in his periodic table for them. Elements with similar properties appeared under each other. Gaps were left for yet to be discovered elements. The periodic table provides a useful framework for analyzing chemical behavior, and is widely used in chemistry and other sciences.

THE HISTORY/DEVELOPMENT OF THE PERIODIC TABLE A necessary prerequisite to the construction of the periodic table was the discovery of the individual elements. Although elements such as gold, silver, tin, copper, lead and mercury have been known since antiquity, the first scientific discovery of an element occurred in 1649 when Hennig Brand discovered phosphorous.

THE HISTORY/DEVELOPMENT OF THE PERIODIC TABLE Mendeleev's table was nine tenths of the way there, but needed one important modification before it became the modern periodic table - the use of atomic number as the organizing principle for the periods. Mendeleev ordered his elements in order of their relative atomic mass, and this gave him some problems. For example, iodine has a lower relative atomic mass than tellurium, so it should come before tellurium in Mendeleev's table - but in order to get iodine in the same group as other elements with similar properties such as fluorine, chlorine and bromine, he had to put it after tellurium, so breaking his own rules. Using atomic number instead of atomic mass as the organizing principle was first proposed by the British chemist Henry Moseley in 1913, and it solved anomalies like this one. Iodine has a higher atomic number than tellurium - so, even though he didn't know why, Mendeleev was right to place it after tellurium after all!

THE PARTS OF AN ELEMENT

THE PARTS OF AN ELEMENT Atomic Number- is the number of protons in the nucleus of an atom of that element. All atoms of an element has the same atomic number. Chemical Symbol- is an abbreviation for the element’s name. The first letter is always capitalized. Any other letter is always lowercase. Chemical Name- The name of the element comes from many sources, such as the property in that element, mendelevium(named after scientists); Californium(named after places) Average Atomic Mass- the weighted average of the masses of all the naturally occurring isotopes(atoms with same number of protons but different numbers of neutrons.)

HOW ARE ELEMENTS ARRANGED ON THE PERIODIC TABLE The elements on the periodic table are classified in three distinct regions: METALS, NONMETALS, METALLOIDS METALS PROPERTIES METALS- are elements that are shiny(luster) and conduct heat and electricity well. solid at room temperature, malleable or able to form in different shapes. ductile- can me made into wires.

METALS ON THE PERIODIC TABLE

NON-METALS PROPERTIES are poor conductors of heat and electricity. dull and brittle. many are gases, others are solid or liquid at room temperature. located at right of the zig-zag line on the periodic table.

NONMETALS ON THE PERIODIC TABLE

METALLOIDS PROPERTIES have properties of metals and some properties of nonmetals. metalloids boarder the zigzag line on the periodic table.

METALLOIDS ON THE PERIODIC TABLE

PARTS OF THE PERIODIC TABLE GROUP/FAMILY A vertical column in the periodic table is a group, or chemical family. Groups are numbered from 1 to 18. Elements in the same group have similar chemical properties. Their properties are similar because all the elements in a group have the same number of valence electrons. Valence Electrons- are he electrons in the outermost energy level of an atom. The number and arrangement of valence electrons tells how atoms of one element will combine with atoms of other elements to form compounds.

GROUPS/FAMILY

GROUPS/FAMILY REACTIVITY Reactivity- is how likely an element is to form compounds with other elements. GROUP 1 The most chemically active metals Known as alkali metals Have only one valence electron which allows them to easily combine with nonmetals. Hydrogen is placed in this group because, like the alkali metals, it has one valence electron.

GROUPS/FAMILY REACTIVITY Are known as Alkaline Earth Metals highly reactive but are slightly less reactive and harder than Group 1 metals. The reactivity of both Group 1 and Group 2 metals increases with increasing atomic number. GROUP 3-12 Are known as the transition metals Generally hard solids with high melting points.

GROUPS/FAMILY REACTIVITY Known as Halogens They are nonmetals They are the most reactive nonmetals. Reactivity in nonmetals increases as atomic number decreases. Which nonmetal is the most reactive? Which nonmetal is the least reactive?

GROUPS/FAMILY REACTIVITY Fluorine is the most reactive nonmetal. Astatine is the least reactive nonmetal. Elements in the Halogen family exist in all three states: Room temperature fluorine(Fl);and Chlorine(Cl) are gases Bromine(Br) is a liquid Iodine(I) and Astatine(At) are solids.

GROUPS/FAMILY REACTIVITY Known as noble gases or inert gases. These gases are the least reactive elements.

PARTS OF THE PERIODIC TABLE PEROID Each horizontal row elements (from left to right) on the periodic table. Atomic size decreases as you move from left to right. The density also decreases Elements at the left and right side of the table are the least dense, and the elements in the middle are the most dense. The atomic number of each element increases by one.

PARTS OF THE PERIODIC TABLE