Introduction to the Electron

What analogy did John Newlands use to describe the periodicity of elements?

• A musical scale

• A planetary orbit

• A deck of cards

• A biological classification system

What was a significant limitation of Niels Bohr's model for describing electron energy levels?

• It could not account for the existence of the nucleus.

• It only worked for single-electron atoms like hydrogen.

• It failed to explain the concept of quanta.

• It incorrectly assumed electrons were stationary.

How did the scientific understanding of electrons evolve from the early atomic models to quantum mechanics?

• From waves to particles.

• From stationary objects to orbiting particles.

• From particles orbiting a nucleus to wave-particle duality.

• From energy packets to discrete matter.

How many electrons can the first electron shell (1s orbital) accommodate?

• One

• Two

• Six

• Eight

Which orbital is typically filled with electrons before the 3d orbital?

• 3p

• 4s

• 4p

• 3s

What is the correct electron configuration for Iron (Fe), which has an atomic number of 26?

• 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁸

• 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶

• 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 4p⁶

• 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰

What is the energy required to remove an electron from an atom to form a positively charged ion called?

• Electron affinity

• Electronegativity

• Ionization energy

• Bond energy

In the periodic table, which block of elements corresponds to the filling of d-orbitals?

• The two columns on the left

• The six columns on the right

• The central block of transition metals

• The two rows at the bottom