Electronic structure

• What is the focus of today's video?

  Arrangement of electrons in atoms
• Why do most atoms have an incomplete outer shell?

  They need a full outer shell to be stable
• What happens if an atom has an incomplete outer shell?

  It reacts with another atom
• What is the atomic number of sodium?

  11
• How many protons does sodium have?

  11 protons
• How are electrons arranged around the nucleus?

  In shells around the nucleus
• How many electrons can the first shell hold?

  2 electrons
• How many electrons can the second shell hold?

  8 electrons
• What is the best way to add electrons to the shells?

  In top, right, bottom, left positions
• What do you do when you run out of electrons for a shell?

  Put remaining electrons in the next shell
• Why is sodium considered unstable?

  It has one electron in its outer shell
• What do most atoms want to do to achieve stability?

  React to form molecules or compounds
• What do noble gases have in terms of electron configuration?

  Completely full outer shells
• What is the atomic number of argon?

  18
• How do you represent the electron structure of argon?

  2, 8, 8
• What is the atomic number of calcium?

  20
• How many electrons does calcium have in its outer shell?

  2 electrons
• What happens to calcium when it loses two electrons?

  It becomes a calcium ion with a 2+ charge
• How do we denote ions in diagrams?

  With square brackets and charge in the corner
• What is the atomic number of fluorine?

  9
• How many electrons does fluorine have in its outer shell?

  7 electrons
• What does fluorine need to become stable?

  Gain one more electron
• What charge does a fluoride ion have?

  -1 charge
• How is the electron structure of fluorine written?

  2, 7
• What is the process of electron arrangement in atoms?

  • Electrons are arranged in shells around the nucleus
  • First shell holds 2 electrons
  • Second shell holds 8 electrons
  • Third shell holds 8 electrons
  • Outer shell must be full for stability
• What are the differences between sodium and fluorine in terms of electron stability?

  • Sodium has 1 electron in outer shell (unstable)
  • Fluorine has 7 electrons in outer shell (needs 1 more to be stable)
• What are the electron configurations for the first 20 elements?

  • Example configurations:
  • Sodium: 2, 8, 1
  • Argon: 2, 8, 8
  • Calcium: 2, 8, 8, 2
  • Fluorine: 2, 7