atom

• What should you be able to describe by the end of the video on atomic structure?


  The nuclear model of atomic structure and its modifications
• How was the Plum Pudding model of atomic structure replaced?


  By the results of the alpha scattering experiment
• What does the nuclear model state about the structure of an atom?


  Most of an atom is empty space with a positive nucleus at the center
• What is contained within the nucleus of an atom?


  Most of the mass of the atom and positive protons
• Who proposed that electrons orbit the nucleus at specific distances?


  Neils Bohr
• What are the specific distances where electrons orbit the nucleus called?


  Energy levels or shells
• What are protons and what do they determine in an atom?


  Protons are positive particles that determine the positive charge in the nucleus
• How many protons does a hydrogen atom have?


  One proton
• How many protons does a helium atom have?


  Two protons
• What did James Chadwick discover about the nucleus?


  That it contains neutral particles called neutrons
• What is the approximate radius of an atom?


  0.1 nanometers or $1 \times 10^{-10} \text{ m}$
• What is the approximate radius of a nucleus?


  $1 \times 10^{-14} \text{ m}$
• How does the radius of the nucleus compare to the radius of the atom?


  The radius of the nucleus is less than 1/10,000 of the radius of the atom
• What is the relative charge of protons?


  Positive one
• What is the relative charge of neutrons?


  Zero
• What is the relative charge of electrons?


  Negative one
• Why do atoms have no overall charge?


  Because the number of electrons equals the number of protons
• What does the term relative mass refer to?


  The mass of one particle compared to another particle
• What is the relative mass of protons and neutrons?


  One
• How does the relative mass of electrons compare to protons and neutrons?


  Electrons have a much smaller relative mass
• Do you need to know the exact relative mass of an electron for the exam?


  No, just that it is very small
• What are the key components of the nuclear model of atomic structure?


  • Positive nucleus at the center
  • Most of the mass is in the nucleus
  • Electrons orbiting at specific energy levels
  • Protons and neutrons in the nucleus
• What are the relative charges and masses of protons, neutrons, and electrons?


  • Protons:
  • Relative charge: +1
  • Relative mass: 1
  • Neutrons:
  • Relative charge: 0
  • Relative mass: 1
  • Electrons:
  • Relative charge: -1
  • Relative mass: very small
• What are the four key concepts you should be able to describe by the end of the video?

  Element, compound, mixture, and molecule
• Why is it essential to understand the definitions of elements, compounds, mixtures, and molecules in chemistry?


  These ideas are fundamental concepts in chemistry
• How many different elements are there approximately?


  Around 100 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 elements are combined in a specific ratio
• 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 the appearance of magnesium sulfide?


  It forms white crystals
• What is required to separate a compound back into its elements?

  A chemical reaction
• What characterizes a mixture?


  Different elements or compounds that are not chemically combined
• What techniques can be used to separate a mixture?


  Physical separation techniques like filtration, distillation, crystallization, or chromatography
• What is a molecule in chemistry?


  A molecule has any elements chemically combined, even if they are the same element