electronic structure

• What does the atomic number indicate?

  Number of protons in the nucleus
• How many protons are in a helium atom?

  Two protons
• Why does a neutral helium atom have two electrons?

  Electrons equal protons in a neutral atom
• What are energy levels in an atom also called?

  Electron shells
• What is the maximum number of electrons the first energy level can hold?

  Two electrons
• How many electrons can the second energy level hold?

  Eight electrons
• What is the maximum number of electrons the third energy level can hold?

  Eight electrons
• How do you represent the electron configuration of hydrogen?

  One electron in the first energy level
• How do you represent the electron configuration of helium?

  Two electrons in the first energy level
• What does the number of electrons in the outer energy level indicate?

  It tells the group number of the element
• What are elements with a full outer energy level called?

  Noble gases
• What is the process for determining the electron configuration of the first 20 elements?

  1. Identify the atomic number.
  2. Assign electrons to energy levels:

  • First level: max 2 electrons
  • Second level: max 8 electrons
  • Third level: max 8 electrons

  1. Count electrons in outer level for group number.
• What is the relationship between electron configuration and group number in the periodic table?

  • The number of electrons in the outer energy level determines the group number.
  • Elements in the same group have similar chemical properties.