Periodic Table of Elements

Dimitri Mendeleev Russian scientist 1869 noticed that he arranged elements by their atomic mass Present day periodic table arranged by atomic #

Period – Horizontal row on the Periodic Table Group/Family – Vertical column on the Periodic Table

Groups…Here’s Where the Periodic Table Gets Useful!! Elements in the same group have similar chemical and physical properties!! (Mendeleev did that on purpose.) Why? They have the same number of valence electrons. They will form the same kinds of ions.

Groups are also called families. They are vertical columns.

Periods Row on the period table Elements in the same period have the same number of electron rings Very different properties as you move across the table Examples: Period 1~ H and He 1 electron shell Period 2~ Li, Be, B, C, N, O, F, 2 electron shells Etc……..

Periods are horizontal rows.

Periodic means having regular patterns or cycles that occur. Chemical symbols- first letter is always capitalized and the second letter is lower case. Elements names are often in different languages. Ex. Sodium (Na) latin word natrium

Alkali Metals 1st column on the periodic table (Group 1) not including hydrogen. Very reactive metals Always combined with something else in nature (like in salt). Soft enough to cut with a butter knife 1 valence electron

Alkaline Earth Metals Second column on the periodic table. (Group 2) Reactive metals Always combined with nonmetals in nature. Several are important mineral nutrients (Mg and Ca) 2 valence electrons

Transition Metals Elements in groups 3-12 Less reactive harder metals Includes metals used in jewelry and construction. Metals used “as metal.”

Halogens Elements in group 17 Very reactive, volatile, diatomic, nonmetals Always found combined with other element in nature Used as disinfectants and to strengthen teeth

The Noble Gases

The Noble Gases Elements in group 18 VERY unreactive (STABLE), monatomic gases Used in lighted “neon” signs Have a full valence shell.

Ions When atom loses or gains an electron becomes either positive or negative ion An ion is an atom that has an electrical charge because it no longer has an equal number of protons and electrons.

Gaining an electron an atom becomes a negative ion (increasing # of negative charges) losing an electron decreases its # of negative charges and becomes a positive ion.

Ions cont. Need to lose or gain 1,2,or 3 electrons to have the energy levels full

Word Bank Periods Groups Metals Metalloids Non-metals Atomic # Mass # Valence electrons Electrons Protons neutrons Electrons Negative ions Positive ions Similar Dissimilar Energy levels

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