Atomic Structure & Periodic Table

• Element

  All of the atoms are the same
• There are around 100 different elements
• Elements are shown in the periodic table
• Symbol


  Every element has a symbol that starts with a capital letter
• The symbol for magnesium is capital M followed by lowercase g
• The symbol for sulfur is simply capital S
• Compound


  Two or more different elements chemically combined in fixed proportions
• Magnesium sulfide is a compound formed from magnesium and sulfur
• Fixed proportions


  For every one atom of magnesium, there is one atom of sulfur in magnesium sulfide
• Properties of compounds


  Compounds usually have totally different properties to the elements they are made from
• Magnesium is a shiny metal and sulfur is a yellow solid
• Magnesium sulfide forms white crystals
• Separating a compound into its elements

  Use a chemical reaction
• Mixture


  Different elements or compounds that are not chemically combined
• A mixture can contain magnesium atoms, sulfur atoms, and magnesium sulfide
• Separating a mixture


  Use a physical separation technique
• Physical separation techniques


  • Filtration
  • Distillation
  • Crystallization
  • Chromatography
• Molecule


  Any elements chemically combined, even if they are the same element
• Molecules


  • Methane
  • Water
  • Ammonia
• Methane contains the elements carbon and hydrogen
• Water contains the elements hydrogen and oxygen
• Ammonia contains the elements nitrogen and hydrogen
• Elements that are also molecules

  • Chlorine molecule
  • Oxygen molecule
• Chlorine molecule contains two chlorine atoms chemically combined
• Oxygen molecule contains two oxygen atoms chemically combined
• Inherent Features

  Describing properties (e.g., physical, chemical) of a substance
• Physical Appearance

  Shape, color, size, etc. (characteristic)
• Chemical Properties

  Include reactivity, corrosiveness, flammability, etc.
• Physical Properties

  Include melting point, boiling point, color, texture, etc.
• Characteristics

  Descriptive phrases that highlight specific features or traits of something
• Properties

  Inherent characteristics or traits of a substance that describe its behavior, appearance, or performance under various conditions