# Warm-up 1/29/08 1. Multiple these exponents ( x 6 ) ( w 2 ) ( x 5 ) ( y 9 ) ( w 4 ) ( x 8 ) 2. Simplify. x -4 · y 3 · z 5 · x 5 · y -1 ÷ z 2.

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Warm-up 1/29/08 1. Multiple these exponents ( x 6 ) ( w 2 ) ( x 5 ) ( y 9 ) ( w 4 ) ( x 8 ) 2. Simplify. x -4 · y 3 · z 5 · x 5 · y -1 ÷ z 2

PS-2.3 Explain the trends of the periodic table based on the elements valence electrons and atomic numbers.

Period is the term used to describe a horizontal row on the periodic table. Group and family are terms used to describe a vertical column on the periodic table.

Metals Metals have 3 or fewer valance electrons. Metals lose electrons when making an ionic bond. Metals are good conductors, malleable, and ductile.

Warm-up 1/31/08 1.Simplify: w · x 2 · z 3 · x -3 · z · w -1 2. Simplify: ab 2 cd 3 · a 2 b 3 cd -1

Metalloids Metalloids have some characteristics of metals and some of nonmetals; they border the line between metals and nonmetals on the periodic table.

Non-Metals

On the EOC, students must: Locate referenced elements when prompted with a period number or group number. Determine a given elements atomic number (number of protons). Determine the number of electrons that an atom of a given element contains (the same as the number of protons-atomic number).

Determine how many energy levels are occupied in a given element (recognize that the period in which an element appears on the periodic table indicates the number of occupied energy levels) For example, all elements in period 4 have four occupied energy levels.

Recognize a given elements atomic mass (the weighted average of the masses of the naturally occurring isotopes of the element). It is always larger than the atomic number and generally increases from left to right on the Periodic Table. Determine the number of valence electrons (electrons in the outer-most energy level), for selected groups of elements when given the elements group number or name.

Group/ FamilyName# valence e- 1Alkali metals1 2Alkaline Earth Metals2 133 144 155 16Oxygen group6 17Halogens7 18Nobel Gasses8 (except He)

Periodic trends in the number of valence electrons: From left to right across periods 1-3: Atoms of all these elements contain one more valence electron than the atoms of the previous element. From top to bottom within any group: Atoms of all of the elements in a given group contain the same number of valence electrons.

Pure Calcium

Periodic trends in the number of energy levels: From left to right across any period: Atoms of all elements in a given period have the same number of energy levels. From top to bottom within any group: Atoms of each subsequent element (from top to bottom) in any given group contain one more energy level than the atoms of the element above.

Homework p. 553 # 1-4 p. 562 # 1-4

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