Atoms- structure

• What is the approximate radius of an atom?

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

  The nucleus is less than 1/1000th the radius of the atom
• Where is most of the mass of the atom concentrated?

  In the nucleus
• What two particles are found in the nucleus?

  Protons and neutrons
• What charge do protons have?

  Positive charge
• What charge do neutrons have?

  No charge
• What is the overall charge of the nucleus?

  Positive charge
• What charge do electrons have?

  Negative charge
• Where are electrons found in an atom?

  In energy levels around the nucleus
• How does the energy of an electron relate to its distance from the nucleus?

  Further energy levels have higher energy
• What happens to an electron when it absorbs electromagnetic radiation?

  It moves from a lower to a higher energy level
• What occurs when an electron emits electromagnetic radiation?

  It returns to a lower energy level
• What are the key concepts related to the structure of atoms?

  • Atoms are very small
  • Radius of an atom: $1 \times 10^{-10} \text{ m}$
  • Nucleus is tiny compared to the atom
  • Nucleus contains protons (positive) and neutrons (neutral)
  • Electrons (negative) are found in energy levels
  • Energy levels further from the nucleus have higher energy
  • Electrons can change energy levels by absorbing or emitting radiation
• What is the relationship between energy levels and electromagnetic radiation?

  Electrons change levels by absorbing or emitting radiation
• What is the basic unit of chemical elements?

  Atoms
• What do atoms contain in their structure?

  Subatomic particles in nucleus and electron cloud
• What are the subatomic particles found in atoms?

  Protons, neutrons, and electrons
• Where are protons and neutrons located in an atom?

  In the nucleus
• Where are electrons located in an atom?

  In the electron cloud surrounding the nucleus
• What is the charge of protons?

  Positive
• What is the charge of neutrons?

  Uncharged
• What is the charge of electrons?

  Negative
• Why are atoms electrically neutral?

  Because the number of protons equals electrons
• How many protons does carbon have?

  6 protons
• What does the electron configuration of carbon look like?

  6 electrons in simple rings around nucleus
• What do the shells around the nucleus represent?

  Different energy levels
• How many electrons can the first shell hold for stability?

  2 electrons
• Why is helium considered stable?

  It has 2 electrons in its shell
• How many electrons does hydrogen have?

  1 electron
• Why is hydrogen chemically reactive?

  It has only 1 electron in its shell
• How many electrons are required for stability in atoms with more than one energy level?

  8 electrons
• Why is neon considered stable?

  It has 8 electrons in its outermost shell
• Why is oxygen chemically reactive?

  It has only 6 electrons in its outermost shell
• What do atoms with fewer than 8 electrons do to become stable?

  They share, gain, or lose electrons
• What is the octet rule?

  Atoms seek 8 electrons for stability
• What are exceptions to the octet rule?

  Hydrogen and helium with one energy level
• What are the basics of atomic structure?

  • Atoms are the basic unit of chemical elements
  • Contain subatomic particles: protons, neutrons, electrons
  • Protons and neutrons in nucleus; electrons in cloud
  • Atoms are electrically neutral due to equal protons and electrons
• What is the significance of electron shells in atoms?

  • Shells represent different energy levels
  • Only outermost shell electrons participate in chemical bonds
  • Stability requires specific electron counts in shells