Chemistry

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Chemistry

• Atomic and Molecular Structure
• 1. The periodic table displays the elements in
  increasing atomic number and shows how
  periodicity of the physical and chemical
  properties of the elements relates to atomic
  structure. As a basis for understanding this
  concept
• a. Students know how to relate the position of an
  element in the periodic table to its atomic
  number and atomic mass.
• b. Students know how to use the periodic table to
  identify metals, semimetals, non-metals, and
  halogens.
• c. Students know how to use the periodic table to
  identify alkali metals, alkaline earth metals and
  transition metals, trends in ionization energy,
  electronegativity, and the relative sizes of ions
  and atoms.
• d. Students know how to use the periodic table to
  determine the number of electrons available for
  bonding.
• e. Students know the nucleus of the atom is much
  smaller than the atom yet contains most of its
  mass.

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Metals, Metalloids, and Nonmetals

• Elements can be grouped into three broad classes
  based on their general properties
• Metals
• Nonmetals
• Metalloids

What does that black line represent?
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Learning About Groups Their Charges
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6.3 - Periodic Trends

• Properties of elements are related to the
  location of elements in the periodic table
• Four periodic trends
• Atomic Radius
• Ionization Energy
• Electron Affinity
• Electronegativity

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GROUPS
PERIODS
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Overall Periodic Trends - BEAR
Electronegativity/ Ionization
Basicity
Atomic Mass
Radius (Atomic)
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• Chemical Bonds
• 2. Biological, chemical, and physical properties
  of matter result from the ability of atoms to
  form bonds from electrostatic forces between
  electrons and protons and between atoms and
  molecules. As a basis for understanding this
  concept
• a. Students know atoms combine to form molecules
  by sharing electrons to form covalent or metallic
  bonds or by exchanging electrons to form ionic
  bonds.
• b. Students know chemical bonds between atoms in
  molecules such as H2, CH4, NH3, H2CCH2, N2, Cl2,
  and many large biological molecules are covalent.
• c. Students know salt crystals, such as NaCl, are
  repeating patterns of positive and negative ions
  held together by electrostatic attraction.

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• Acids and Bases
• 5. Acids, bases, and salts are three classes of
  compounds that form ions in water solutions. As a
  basis for understanding this concept
• a. Students know the observable properties of
  acids, bases, and salt solutions.
• c. Students know strong acids and bases fully
  dissociate and weak acids and bases partially
  dissociate.

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Acids Bases

• Acids produce hydrogen ions H in water
  solution
• Bases dissociate to produce a metal ion and
  hydroxide ions OH - in water solution

-
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Strong/Weak Acids and Bases

• Strong Acid An acid that has a very low pH
  (0-4).
• Strong Base A base that has a very high pH
  (10-14).
• Weak Acid An acid that only partially ionizes in
  an aqueous solution. That means not every
  molecule breaks apart. They usually have a pH
  close to 7 (3-6).
• Weak Base A base that only partially ionizes in
  an aqueous solution. That means not every
  molecule breaks apart. They usually have a pH
  close to 7 (8-10).

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The pH Concept

• The pH of a solution describes its acidity
• The pH scale is a log scale that corresponds to
  the hydrogen ion concentrations of aqueous
  solutions
• The pH scale ranges from 0 to 14.
• A pH value less than 7 corresponds to an acidic
  solution a pH value greater than 7 indicates a
  basic solution.
• A quick way to remember the pH scale

Acidic Solution pH lt 7
Neutral Solution pH 7
Basic Solution pH gt 7

-14

-14
-14

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Thermodynamics

• Chemical Thermodynamics
• 7. Energy is exchanged or transformed in all
  chemical reactions and physical changes of
  matter. As a basis for understanding this
  concept
• b. Students know chemical processes can either
  release (exothermic) or absorb (endothermic)
  thermal energy.
• c. Students know energy is released when a
  material condenses or freezes and is absorbed
  when a material evaporates or melts.

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Flow of Energy

• Heat (q) Energy that transfers from one object
  to another.
• Heat always flows from a warmer object to a
  cooler object.

HEAT
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Exothermic

• If a chemical reaction RELEASES energy/heat, it
  is exothermic.
• If you put water in the freezer, it releases heat
  as it freezes and becomes ice.
• Condensation and freezing are both exothermic
  reactions.

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Exothermic vs. Endothermic Processes
Exothermic (-q) Endothermic (q)
Releases energy/heat ( - ) Absorbs energy/heat ( )
Condensation and Freezing Evaporation and Melting
System loses heat, as the surrounding heat up (example - sweating while running) System gains heat, as surrounding cool down (example - sitting by a fire)
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Endothermic

• If a chemical reaction ABSORBS energy/heat, it is
  endothermic.
• If you put water on the stove, it absorbs heat as
  it boils and then evaporates.
• Melting and evaporation are both endothermic
  reactions.