Chemistry 8th grade honors

• the number of protons is the atomic number
• If you change the # of atoms in an element a new element is created
• protons and neutrons tell us the mass of an atom
• A valance electron is a electron that is on the outermost energy level
• valance electron determine reactivity of an element
• elements is composed of a single atom
• a mixture is a physical combination of 2 or more atoms
• a coefficient is the number placed before the element symbol for example 3Fe
• A subscript is a small number placed after an element symbol
• The properties of metals are

  malleable

  shiny luster

  conductive

  most are magnetic

  ductile
• The properties of nonmetals are

  brittle

  dull luster

  non-conductive

  non-magnetic
• The most reactive group on the periodic table is alkaline metals and halogens
• Groups tell me about the elements that share the same properties↕️
• Periods tell me about the energy levels ↔️
• Chemical change is when one or more substances are changed into new substances that have different properties
• Physical change is a change in the state of matter, but not in the composition of the substance.
• 5 things that show chemical change has occurred is

  • Color change
  • gas production
  • light production
  • change in temp
  • precipitate formed
• Law Of Conservation Of Mass is that its chemical reaction is neither created or destroyed
• A reactant is a substance that is used to form a product in a chemical reaction.
• a product is what you end up with after a reaction has taken place, it is the end result of a reaction