VALENCE SHELL

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VALENCE SHELL

• OUTERMOST ENERGY LEVEL CONTAINING ELECTRONS IN
  THE GROUND STATE

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VALENCE ELECTRONS

• ELECTRONS IN VALENCE SHELL
• DETERMINE MOST CHEMICAL PROPERTIES (VERY
  IMPORTANT)

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VALENCE ELECTRON EFFECTS

• ELEMENTS WITH THE SAME NUMBER OF VALENCE
  ELECTRONS TEND TO REACT SIMILARLY
• GROUP VIII ELEMENTS HAVE COMPLETE VALENCE SHELLS
  SO DONT REACT

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PERIODIC TABLE

• ARRANGED FROM LOWEST TO HIGHEST ATOMIC NUMBER
• PERIOD HORIZONTAL ROW
• ELEMENTS IN PERIODS HAVE SAME VALENCE SHELL
• FAMILY OR GROUP VERTICAL COLUMN

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PERIODIC TABLE II

• ELEMENTS IN GROUP HAVE THE SAME NUMBER OF VALENCE
  ELECTRONS
• GROUPS CORRELATE TO SUBLEVELS

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ELECTRON DOT SYMBOLS

• ALSO CALLED LEWIS DOT SYMBOLS
• DOT SYMBOLS SHOW ONLY VALENCE ELECTRONS

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DOT SYMBOL RULES

• SHOW ELEMENT SYMBOL
• USE 4 SIDES TOP, RIGHT, BOTTOM, LEFT
• ONLY 2 DOTS PER SIDE
• 1ST DOT GOES ON ANY SIDE

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DOT SYMBOLS RULES II

• 2ND DOT PAIRS WITH 1ST
• REMAINING DOTS ARRANGED 1 PER SIDE UNTIL YOU HAVE
  TO DOUBLE

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METALS

• SUBSTANCE HAVING 1-3 VALENCE ELECTRONS
• USUALLY LOSES ELECTRONS WHEN REACTING
• FOUND LEFT OF THE STAIR STEPS ON THE PERIODIC
  TABLE

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PROPERTIES OF METALS

• MALLEABLE CAN BE HAMMERED (FORMED) INTO SHEETS
• DUCTILE CAN BE DRAWN INTO A WIRE
• CONDUCT ELECTRICITY AND HEAT
• LUSTER - SHINY

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NONMETALS

• SUBSTANCE HAVING 5-7 VALENCE ELECTRONS
• USUALLY GAINS ELECTRONS WHEN REACTING
• FOUND RIGHT OF THE STAIR STEPS ON THE PERIODIC
  TABLE

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PROPERTIES OF NONMETALS

• BRITTLE CAN NOT BE FORMED INTO SHAPES
• DO NOT CONDUCT ELECTRICITY OR HEAT

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METALLOIDS

• SUBSTANCES HAVING 3-5 VALENCE ELECTRONS
• CAN GAIN OR LOSE ELECTRONS WHEN REACTING
• ALONG THE STAIR STEPS ON THE PERIODIC TABLE
• Si, As, Ge, Sb

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NOBLE GASES

• SUBSTANCE HAVING 8 (OR 2) VALENCE ELECTRONS
• DO NOT GAIN OR LOSE ELECTRONS SO THEY DO NOT
  REACT (CALLED INERT)
• FOUND IN RIGHTMOST COLUMN OF PERIODIC TABLE

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PERIODIC LAW

• ELEMENTS SHOW A REPEATING PATTERN WHEN ORGANIZED
  BY ATOMIC NUMBER

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EXAMPLES

• ATOMIC SIZE, VALENCE ELECTRONS, AND CHEMICAL
  REACTIVITY
• EACH PERIOD GOES FROM 1 TO 8 VALENCE ELECTRONS
  (NOT INCLUDING THE B GROUPS

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TRENDS

• ATOMS BECOME SMALLER ACROSS A PERIOD
• ATOMS BECOME LARGER DOWN A GROUP

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NAMED FAMILIES

• IA ALKALI METALS (EXCLUDING HYDROGEN)
• IIA ALKALINE EARTH METALS
• VIIA HALOGENS
• VIII NOBLE GASES

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FAMILY CHARACTERISTICS

• ALL HAVE THE SAME NUMBER OF VALENCE ELECTRONS
• SIMILAR CHEMICAL PROPERTIES

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CHEMICAL STABILITY

• 8 ELECTRONS IN A VALENCE SHELL IS CALLED A STABLE
  OCTET
• 2 ELECTRONS IN A VALENCE SHELL IS A STABLE DUET

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REACTIONS

• ELECTRONS MAY BE TRANSFERRED OR SHARED
• ATOMS REACT TO FORM STABLE VALENCE CONFIGURATIONS
  (8 OR 2 VALENCE ELECTRONS)

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CHEMICAL BOND

• FORCE OF ATTRACTION (FOA) BETWEEN ATOMS DUE TO
  OPPOSITE CHARGES
• TYPES INCLUDE IONIC, COVALENT, AND METALLIC
• ALL INVOLVE MOVEMENT OF VALENCE ELECTRONS
• FORMATION IS EXOTHERMIC

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ION

• ATOM WITH THE WRONG NUMBER OF ELECTRONS

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CATION

• POSITIVELY CHARGED ATOM
• LOST 1 OR MORE ELECTRONS

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ANION

• NEGATIVELY CHARGED
• GAINED 1 OR MORE ELECTRONS

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IONIC BOND

• FOA DUE TO THE TRANSFER OF ONE OR MORE VALENCE
  ELECTRONS FROM ONE ATOM TO ANOTHER
• ATOMS ATTRACT DUE TO OPPOSITE CHARGES
• RESULTING COMPOUND IS IONIC COMPOUND

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IONIC COMPOUNDS

• NEUTRAL
• REGULAR REPEATING PATTERNS CALLED CRYSTALS (NOT
  MOLECULE)
• HAVE STRONG BONDS CAUSING THEM TO BE BRITTLE
  SOLIDS AT ROOM TEMP, AND HAVE HIGH MP

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IONIC CMPDS II

• SEPARATE INTO IONS (DISSOCIATE) WHEN DISSOLVED IN
  WATER
• AQUEOUS SOLUTIONS CONDUCT ELECTRICITY
• CALLED ELECTROLYTES

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COVALENT BONDS

• FOA DUE TO SHARNG ONE OR MORE PAIRS OF VALENCE
  ELECTRONS, EACH ATOM CONTRIBUTING ONE ELECTRON IN
  A PAIR
• ELECTRON PAIR JUMPS BACK AND FORTH BETWEEN ATOMS

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COVALENT BOND II

• TEMPORARY CHARGES THAT CAUSE ATTRACTION
• RESULTING COMPOUND IS CALLED COVALENT (OR
  MOLECULAR)
• CAN HAVE DOUBLE AND TRIPLE COVALENT BONDS

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COVALENT COMPOUNDS

• NEUTRAL
• FORM MOLECULES (NOT CRYSTALS)

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• HAVE WEAK ATTRACTION FORCES BETWEEN MOLECULES
  CAUSING THEM TO BE GASES OR LIQUIDS AT ROOM TEMP
  AND TO HAVE LOW MELTING POINTS

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COVALENT CMPDS II

• DO NOT DISSOCIATE IN WATER
• NOT USUALLY ELECTROLYTES

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COVALENT CRYSTALS

• LARGE COVALENTLY BONDED STRUCTURES
• STRONG AND A VERY HIGH MP
• ONLY A FEW KINDS OF ATOMS CAN FORM THESE
• EXAMPLES DIAMOND AND CARBORUNDUM

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MOLECULE OR COMPOUND

• A MOLECULE IS TWO OR MORE ATOMS COVALENTLY BONDED
• A COMPOUND IS TWO OR MORE DIFFERENT ATOMS
  CHEMICALLY BONDED

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DIATOMIC MOLECULE

• TWO ATOMS OF THE SAME ELEMENT COVALENTLY BONDED
• SEVEN DIATOMIC ELEMENTS H, N, O, F, Cl, Br, and
  I
• HORSES NEED OATS FOR CLEAR BROWN EYES

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METALLIC BONDS

• FOA CAUSED BY SHARING LOOSELY HELD VALENCE
  ELECTRONS AMONG MANY METAL IONS
• CAUSES PROPERTIES OF LUSTER, CONDUCTIVITY,
  MALLEABILITY, AND DUCTILITY

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METALLIC BONDS II

• USUALLY BETWEEN LIKE ATOMS IN A PIECE OF THE
  ELEMENT
• TWO DIFFERENT METALS FORM MIXTURES CALLED ALLOYS,
  NOT COMPOUNDS
• MIXTURES STILL SHOW METALLIC PROPERTIES

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PREDICTING BOND TYPES

• IONIC BOND FORMED BETWEEN A METAL AND A NONMETAL
• COVALENT BOND IS FORMED BETWEEN TWO NONMETALS
• METALLIC BOND IS FORMED BETWEEN TWO METALS

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EXCEPTION

• HYDROGEN ALWAYS FORMS COVALENT BONDS EXCEPT WITH
  FLUORINE