Atomic Structure and the Periodic Table

• How many different elements are there approximately?

  About 100 different elements
• What is a Compound?

  
  

  
  

  Substance made up of two or more elements chemically combined in a fixed ratio by weight.
• How can compounds be separated into elements?

  By chemical reactions
• What do chemical reactions involve?

  Formation of new substances
• How can mixtures be separated?

  By physical processes
• What is a mixture?

  Two or more substances not chemically combined
• What is the plum pudding model of the atom?

  Positive charge with negative electrons embedded
• What did the alpha particle scattering experiment conclude?

  Mass is concentrated at the nucleus
• Who adapted the nuclear model of the atom?

  Niels Bohr
• What is the atomic number of an element?

  Number of protons in an atom
• What is the radius of an atom approximately?

  About 0.1 nm
• Where is most of the mass of an atom located?

  In the nucleus
• What are isotopes?

  Atoms of the same element with different numbers of neutrons and same number of protons.
• What is the relative mass of a neutron compared to a proton?

  Similar to a proton

  
• What is the size of a nucleus compared to an atom?

  Less than 1/10,000 of the atom
• How can the numbers of protons, neutrons, and electrons be calculated?

  Using atomic number and mass number
• What is the relationship between electrons and protons in an atom?

  They are equal in number
• What does the term 'relative atomic mass' refer to?

  Mass of an atom compared to carbon-12
• What is the approximate radius of an atom?

  About 0.1 nm
• How does the radius of a nucleus compare to that of an atom?

  Less than 1/10,000 of an atom
• Where is most of an atom's mass located?

  In the nucleus
• What is the mass number of an atom?

  Sum of protons and neutrons
• What are isotopes?

  Atoms of the same elements with the same number of protons but different numbers of neutrons
• How can you represent an atom?

  Using atomic number and mass number
• What should students be able to calculate regarding atoms or ions?

  Numbers of protons, neutrons, and electrons

  
• What is the relative atomic mass of an element?

  An average value considering isotopes' abundance

  
• How can you calculate the relative atomic mass of an element?

  Using the percentage abundance of isotopes
• Where do electrons occupy in an atom?

  Lowest available energy levels
• How can the electronic structure of sodium be represented?

  As 2,8,1
• What do elements in the same group of the periodic table have in common?

  Same number of outer shell electrons
• How does the position of an element relate to its properties?

  It relates to the arrangement of electrons
• What can be predicted from an element's position in the periodic table?

  Possible reactions and reactivity
• How did early scientists classify elements before protons, neutrons, and electrons were discovered?

  By arranging them by atomic weights
• What issue did early periodic tables face?

  Some elements were placed in inappropriate groups
• How did Mendeleev improve the periodic table?

  By leaving gaps for undiscovered elements
• What knowledge helped explain the order based on atomic weights?

  Knowledge of isotopes
• What defines metals in terms of ion formation?

  metal atoms lose electrons to form positive ions
• Where are metals primarily located in the periodic table?

  Left and bottom of the table
• What characterizes non-metals in terms of ion formation?

  Non-metals gain electrons forming Negative ions.
• How do the properties of metals and non-metals differ?

  
  

  Metals are typically shiny, malleable, ductile, and good conductors of heat and electricity.Non-metals, in contrast, are dull, brittle, and poor conductors of heat and electricity