CHEMISTRY

• What are the four key concepts you should be able to describe by the end of the video?

  Element, compound, mixture, and molecule
• How many different elements are there approximately?

  Around 118 different elements
• Where are the elements shown?


  In the periodic table
• What does each symbol in the periodic table represent?


  A different element
• What is the symbol for magnesium?


  Capital M followed by lowercase g
• What is the symbol for sulfur?


  Capital S
• What defines an element?


  All of the atoms in an element are the same
• What happens when atoms of magnesium and sulfur are chemically combined?


  They form a compound called magnesium sulfide
• What is the definition of a compound?


  A compound contains two or more different elements chemically combined in fixed proportions
• What does "fixed proportions" mean in the context of compounds?


  It means the ratio of elements in the compound is constant
• How do the properties of compounds compare to the elements they are made from?


  Compounds usually have totally different properties than the elements
• What is an example of a compound and its properties?

  Magnesium is a shiny metal, sulfur is a yellow solid, but magnesium sulfide forms white crystals
• What is required to separate a compound back into its elements?

  A chemical reaction
• What characterizes a mixture?


  A mixture contains different elements or compounds that are not chemically combined
• How can mixtures be separated?


  Using physical separation techniques
• What are some examples of physical separation techniques?

  Filtration, distillation, crystallization, and chromatography
• What is a molecule in chemistry?


  A molecule has any elements chemically combined, even if they are the same element
• What are examples of molecules that are also compounds?


  Methane, water, and ammonia
• What elements are contained in methane?


  Carbon and hydrogen
• What elements are contained in water?


  Hydrogen and oxygen
• What elements are contained in ammonia?


  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
• What is the chlorine molecule composed of?


  Two chlorine atoms chemically combined
• What is the oxygen molecule composed of?


  Two oxygen atoms chemically combined
• What are the key differences between elements, compounds, mixtures, and molecules?


  • 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, including the same element.
• What are the physical separation techniques mentioned?

  • Filtration
  • Distillation
  • Crystallization
  • Chromatography
• What is the significance of the periodic table in chemistry?


  • Displays all known elements
  • Each symbol represents a different element
  • Essential for identifying elements in compounds and mixtures
• What is the relationship between compounds and their constituent elements?


  • Compounds have different properties than the elements they are made from
  • Compounds are formed through chemical reactions
  • Elements retain their individual properties when in a mixture
• abundance


  The amount of something present, like how much of a particular element is found in a sample.
• atom


  the smallest part of an element to exist
• atomic number


  The number of protons in the nucleus of an atom; it defines the element.
• aqueous 


  Something that is dissolved in water.
• compound


  A substance made from two or more different elements that are chemically bonded together.
• electron


  a tiny, negatively charged particle that orbits the nucleus of an atom.
• How does a more reactive halogen interact with a less reactive halogen in an aqueous solution?

  A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.
• What are the elements in group seven called?

  Halogens
• What happens when a halogen reacts with a metal?

  The halogen atom gains one electron to achieve a full outer energy level.
• Which halogen is the most reactive element in group seven?

  Fluorine
• Why does reactivity decrease as you move down group seven?

  Because the distance between the outer energy level and the nucleus increases, and there is greater shielding.
• What are the products of the reaction between potassium iodide and chlorine?

  Potassium chloride and iodine are produced.