PERIODIC TABLE

(1869) Dmitri Mendeleev(Russian chemist) shows a first version of the periodic table. He noticed that classifying the elements by their atomic mass a periodicity in certain properties could be seen. The first table consisted of 63 elements. Periodicity: the regular repeating of properties according to the arrangement of elements in the PT.

*Henry Mosely(British) discovered nuclear charges of all known elements and that chemical properties of elements are related to their atomic numbers but not atomic weights.

He stated that elements should be arranged in order of increasing atomic numbers. So, today’s periodic table was formed.

In modern periodic table, elements are listed in order of increasing atomic numbers. Elements with similar chemical properties are placed in the same vertical columns.

1A: Alkali metals 2A: Alkaline earth metals 3A: Earth metals 7A: Halogens 8A: Noble(Inert)gases

GROUPS/FAMILIES: The vertical columns The vertical columns Elements in the same group have Elements in the same group have -similar chemical properties(exception: H in 1A group) -Same number of valence electrons and orbitals.(exception:He in 8A group)

GROUPS/FAMILIES: -similar chemical properties(exception: H in 1A group) For example, all 1A metals react vigorously with water. For example, all 1A metals react vigorously with water.

* *For A groups; # of valence electrons= # of the group(except He in 8A) in 7A;number of valence electrons=7

PERIODS: The horizontal rows The horizontal rows There are 7 periods There are 7 periods Valence shell determines the period number Valence shell determines the period number Each of them starts with a metal and ends with a noble gas.(except first and seventh ones) Each of them starts with a metal and ends with a noble gas.(except first and seventh ones) Elements in the same period have the same # of energy levels or shells or principle quantum numbers. Elements in the same period have the same # of energy levels or shells or principle quantum numbers.

Metals lie to the left of the zig-zag line. Nonmetals lie to the right of the zig-zag line. Over 80 % of the known elements are metals.

Differences between Metals and Nonmetals: Metals always lose electrons in compounds. The ease with losing an electron forms the metallic character of elements. Tendecy in gaining electrons forms the nonmetallic character.

PROPERTIES OF METALS Conduct the heat and electricity in their molten(liquid) and solid states. Solid at room conditions except Hg. Always lose electron in chemical rxns.Thus, they can only form CATIONS. Ductile(can be drawn out to make wires) and malleable (can be beaten into sheets). Have lustre (shiny) appearance. Have high melting points.

PROPERTIES OF METALS Sonorous (Make a ringing noise when struck) Have high density. Hard (except some metals: Na, Mg) Cannot form compounds w/ each other. Instead, they can only form homogeneous mixtures called “ alloys.”(e.g., bronze, stel, solder, brass)

PROPERTIES OF NONMETALS do NOT conduct the electricity, except graphite(C). can be solid, liquid, or gas at room conditions. This shows that they have lower melting points than metals. Tend to gain electrons or share electrons in their compounds.Therefore, the form negative (ANIONS) ions in compounds (except H, which can also be H + ).

PROPERTIES OF NONMETALS Solid nonmetals have lower density compared to metals. are brittle. have dull appearance.

Which ones of these properties of metals and nonmetals are physical /chemical? Which ones of these properties of metals and nonmetals are physical /chemical?

Increasing nonmetallic character(Except 8A) Increasing nonmetallic character

Metallic and Nonmetallic activity -Metallic activity decreases -Nonmetallic activity increases -Metallic activity increases -Nonmetallic activity decreases

Which elements are the most reactive metals and nonmetals in the periodic table? Which elements are the most reactive metals and nonmetals in the periodic table?

Francium(Fr) and Cesium(Cs) in 1A are the most reactive metals. Francium(Fr) and Cesium(Cs) in 1A are the most reactive metals. Fluorine(F) in 7A is the most reactive nonmetal. Fluorine(F) in 7A is the most reactive nonmetal.

Important Groups

Each Noble gas has 8 valence electrons in their outer shells,except He. He has 2 valence electrons. Each Noble gas has 8 valence electrons in their outer shells,except He. He has 2 valence electrons. Because of their STABLE ELECTRON ARRANGEMENTS, they are stable and UNREACTIVE! Because of their STABLE ELECTRON ARRANGEMENTS, they are stable and UNREACTIVE! All other elements try to have the electron arrangement of Noble gases in their compounds. All other elements try to have the electron arrangement of Noble gases in their compounds. GROUP 0- A SPECIAL GROUP!!! NOBLE (Inert)GASES(VIIIA):

They are gaseous at room conditions. They are gaseous at room conditions. The Nobel gases are used in neon signs.Each nobel gas glows a different colour when electricity is passed through it. The Nobel gases are used in neon signs.Each nobel gas glows a different colour when electricity is passed through it. For instance, Helium glows pink,neon glows orange-red, and argon glows purple.It isn’t just neon in those signs! For instance, Helium glows pink,neon glows orange-red, and argon glows purple.It isn’t just neon in those signs!

Jellyfish lamps made with noble gases

OXIDATION STATES OF ELEMENTS Oxidation state (or valency) is the positive or negative charge that an atom gets when it forms a compound. Oxidation state (or valency) is the positive or negative charge that an atom gets when it forms a compound.

OXIDATION STATES OF ELEMENTS Group IAIIAIIIAIVAVAVIAVIIAVIII A MAX (+) NA MIN (-) NA NA

References YrY(Date of accession: 14/11/2011) YrY(Date of accession: 14/11/2011) YrY(Date YrY(Date