elements , compounds and mixtures

• What are the definitions of an element, a compound, a mixture, and a molecule?


  • Element: All atoms are the same.
  • Compound: Two or more different elements chemically combined in fixed proportions.
  • Mixture: Different elements or compounds not chemically combined.
  • Molecule: Any elements chemically combined, even if they are the same.
• How many different elements are there approximately?


  There are around 100 different elements.
• Where are the elements shown?


  The elements are shown in the periodic table.
• What does each symbol in the periodic table represent?


  Each symbol represents a different element.
• What is the symbol for magnesium?


  The symbol for magnesium is capital M followed by lowercase g.
• What is the symbol for sulfur?


  The symbol for sulfur is simply capital S.
• What happens when atoms of magnesium and sulfur are chemically combined?


  They form a compound called magnesium sulfide.
• What do compounds contain?


  Compounds contain two or more different elements chemically combined in fixed proportions.
• What does "fixed proportions" mean in the context of magnesium sulfide?

  It means that for every one atom of magnesium, there is one atom of sulfur.
• How do the properties of compounds compare to the elements they are made from?


  Compounds usually have totally different properties from the elements they are made from.
• What is the appearance of magnesium and sulfur?


  Magnesium is a shiny metal, and sulfur is a yellow solid.
• What is required to separate a compound back into its elements?


  A chemical reaction is required to separate a compound back into its elements.
• What characterizes a mixture?

  A mixture has different elements or compounds that are not chemically combined.
• What techniques can be used to separate a mixture?


  Filtration, distillation, crystallization, or chromatography can be used.
• What is a molecule in chemistry?


  A molecule has any elements chemically combined, even if they are the same element.
• What are examples of compounds mentioned in the material?


  Methane, water, and ammonia are examples of compounds.
• What elements are contained in methane?


  Methane contains the elements carbon and hydrogen.
• What elements are contained in water?


  Water contains the elements hydrogen and oxygen.
• What elements are contained in ammonia?


  Ammonia contains the elements nitrogen and hydrogen.
• What is the difference between a molecule and a compound?


  A molecule can consist of the same element, while a compound consists of different elements chemically combined.
• What is the composition of a chlorine molecule?


  A chlorine molecule contains two chlorine atoms chemically combined.
• What is the composition of an oxygen molecule?


  An oxygen molecule contains two oxygen atoms chemically combined.
• What is the difference between elements, compounds, and mixtures?


  • Elements: Pure substances made of one type of atom.
  • Compounds: Substances formed from two or more different elements chemically combined.
  • Mixtures: Combinations of two or more substances that are not chemically combined.
• What are the key characteristics of compounds and mixtures?


  • Compounds:
  • Fixed proportions of elements.
  • Different properties from constituent elements.
  • Require chemical reactions for separation.
  • Mixtures:
  • No fixed proportions.
  • Retain properties of individual components.
  • Can be separated using physical methods.