Electron Structure

• What is the main topic discussed in the video?

  The arrangement of electrons in atoms
• Why do most atoms, like fluorine, have an incomplete outer shell of electrons?

  Because they need a full outer shell to be stable
• What happens when atoms do not have a full outer shell?

  They will react with another atom to gain or lose electrons
• What is the atomic number of sodium?

  11
• How many protons and electrons does sodium have?

  Sodium has 11 protons and 11 electrons
• How are electrons arranged around the nucleus of an atom?

  Electrons are arranged in shells around the nucleus
• How many electrons can the first shell hold?

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

  The second shell can hold up to 8 electrons
• What is the recommended order for adding electrons to the shells?

  Add a single electron to the top, right, bottom, and left positions before pairing them
• What happens when the first shell is filled?

  The next electrons are added to the second shell
• How many electrons does sodium have in its outer shell?

  Sodium has one electron in its outer shell
• Why is sodium considered unstable?

  Because it has an incomplete outer shell
• What do most atoms want to do to achieve stability?

  They want to react to form molecules or compounds
• What are the noble gases known for?

  Noble gases have completely full outer shells
• What is the atomic number of argon?

  18
• How do you represent the electron structure of an atom using numbers?

  By using a format like 2, 8, 8
• How many electrons does calcium have?

  Calcium has 20 electrons
• What is the electron structure of calcium?

  2, 8, 8, 2
• Why is calcium considered unstable?

  Because it has only two electrons in its outer shell
• What happens to calcium when it loses two outer electrons?

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

  By drawing big square brackets around them and writing the overall charge in the top right corner
• What is the atomic number of fluorine?

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

  Fluorine has seven electrons in its outer shell
• What does fluorine need to do to become stable?

  Fluorine needs to gain one more electron
• What charge does fluorine have when it becomes a fluoride ion?

  Fluorine has a charge of -1 when it becomes a fluoride ion
• How is the electron structure of fluoride represented?

  As 2, 8
• What are the key points about electron arrangement in atoms?

  • Atoms need a full outer shell to be stable.
  • Electrons are arranged in shells around the nucleus.
  • The first shell holds 2 electrons, the second holds 8, and the third holds 8.
  • Atoms react to achieve a full outer shell.
  • Noble gases have full outer shells and are stable.
• How do you determine the electron arrangement of an element?

  1. Find the atomic number of the element.
  2. Draw the nucleus and shells.
  3. Fill the first shell with 2 electrons.
  4. Fill the second shell with 8 electrons.
  5. Fill the third shell with 8 electrons.
  6. If there are remaining electrons, place them in the next shell.
  7. Represent the arrangement as numbers (e.g., 2, 8, 8).