Science assessment packet

• Protons

  Positive charged subatomic particles found in the nucleus; determine the identity of an element
• Neutrons


  Neutral charged subatomic particles found in the nucleus
• Electrons


  Negative charged subatomic particles found in the electron cloud surrounding the nucleus
• Group/Family Number


  The number of valence electrons for certain elements can be determined from the group number (Groups 1, 2, 13-18)
• Group 1


  • Hydrogen (H) contains 1 valence electron
• Group 13


  • Boron (B) contains 3 valence electrons
• If the group number is two digits, you only need to look at the 2nd digit to determine the valence number
• Groups/Families


  • Vertical columns on the Periodic Table
  • There are 18 Groups/Families
  • Elements in the same Group/Family have similar properties
• Group names


  • Group 1 = Alkali Metals
  • Group 2 = Alkaline Earth Metals
  • Groups 3-12 = Transition Metals
  • Group 17 = Halogens
  • Group 18 = Noble Gases
• Period Number


  The number of energy levels/shells can be determined from the period number
• Calcium (Ca)


  • Belongs to Period 4, so it contains 4 energy levels/shells
• Periods


  • Horizontal rows on the Periodic Table
  • There are 7 Periods
  • Proton number increases as you move to the right of each period
  • Reactivity of metals generally decreases as you move to the right of each period
• Metals


  • Shiny
  • High melting point
  • Mostly silver or gray in color
  • Mostly solids at room temperature - Mercury (Hg) is a liquid at room temperature
  • Malleable - able to be hammered into a thin sheet
  • Ductile - able to be drawn/pulled into a wire
  • Good conductors of heat and electricity
• Nonmetals


  • Dull
  • Low melting point
  • Brittle - break easily
  • Not malleable
  • Not ductile
  • Poor conductors of heat and electricity
• Metalloids


  • Found on the "zig-zag" line on the Periodic Table of Elements
  • Have properties of both metals and nonmetals
  • Can be shiny or dull
  • Semiconductors - able to conduct electricity under certain conditions
• Elements


  • Pure substances
  • Substances that are not able to be broken down chemically
  • Found on the Periodic Table of Elements
  • Hydrogen and Helium are the most common elements in the universe
  • Oxygen and Silicon are the most common elements in Earth's crust
• Compounds


  • Pure substances
  • Composed of two or more different elements chemically combined (bonded)
• Mixtures


  Composed of two or more different elements or compounds that are not chemically combined
• Organic Compounds


  Compounds that contain Carbon and at least one atom of Hydrogen, Oxygen, Phosphorus, Sulfur, or Nitrogen
• Elements (representation)


  • Represented by capital letters
  • Contain 1 or 2 letter symbols (first letter is capitalized, second letter is lower case)
• Atoms (representation)


  • Represented by a subscript
  • Located after the symbol of each element
  • Written as a small number
  • Add the atoms of each element in the formula to determine the total number of atoms
  • If there is no subscript after an element's symbol, then there is just 1 atom of that specific element
• Molecules (representation)


  • Represented by a coefficient
  • Located at the beginning of a chemical formula
  • Written as a large number
  • Must multiply the number of atoms by the coefficient to determine the total number of atoms
  • If there is no coefficient at the beginning of a specific formula, then there is just 1 molecule
• Reactants


  • Located on the left side of the equation
  • Elements or compounds that are present before a reaction takes place
• Products


  • Located on the right side of the equation
  • Elements or compounds that are present after a reaction takes place (new substances)
• Balanced and Unbalanced Chemical Equations


  1. Find the number of atoms of each element on the reactant side

  2. Find the number of atoms of each element on the product side

  3. If the number of atoms of each element are the same on the reactant and product side then the equation is balanced

  4. If the number of atoms of each element are NOT the same then the equation is unbalanced