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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.
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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 TableGroup/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.
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……..
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 • 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
Periods Groups Metals Metalloids Non-metals Atomic # Mass # Valence electrons Electrons Protons neutrons Electrons Negative ions Positive ions Similar Dissimilar Energy levels Word Bank
Open text book to Page 74 • Read pages 74 - 78