Atomic Models and Electron Configuration

This set of flashcards reviews key concepts in Atomic Theory and Electron Configuration, including historical models, electron behavior, and important principles.

What does the term 'atomos' refer to in the context of Democritus's model of the atom?

It means 'uncuttable' and describes the indivisible nature of atoms.

What is the Law of Conservation of Mass?

Mass is neither created nor destroyed, only transferred from one form to another.

Who formulated Dalton’s Atomic Theory?

John Dalton in 1808.

What is the primary idea in Dalton's Atomic Theory regarding atoms of different elements?

Atoms of different elements are different in size, mass, and other properties.

What did J.J. Thomson discover in 1897?

The electron, using a Crookes tube or cathode ray tube.

How did Thomson describe the structure of the atom in his Plum Pudding Model?

Negative electrons are like 'plums' in a positively charged 'pudding'.

Who discovered the proton and when?

Eugen Goldstein discovered the proton in 1886.

What did Rutherford's Gold Foil Experiment demonstrate?

It proved the existence of a dense, positively charged nucleus in the atom.

What did Hantaro Nagaoka propose about the atomic model?

A planetary model with electrons revolving around a massive center, like the rings of Saturn.

What does the Bohr Model explain about electrons?

Electrons exist in quantized energy levels that can change with energy absorption or emission.

What defines valence electrons in an atom?

Electrons found in the outermost 'ring' or energy level of the atom.

What distinguishes core electrons from valence electrons?

Core electrons are not involved in chemical bonding, while valence electrons participate in chemical reactions.

What principle states that only two electrons can occupy an orbital?

The Pauli Exclusion Principle.

What does Hund’s Rule state about electron arrangement in orbitals?

Electrons must occupy all degenerate orbitals singly before pairing up.

What do quantum numbers identify for each electron?

Energy level, shape of atomic orbital, orientation, and spin of the electron.

What is the difference between cations and anions?

Cations are positively charged ions formed by losing electrons, while anions are negatively charged ions formed by gaining electrons.

How does a positive ion (cation) form?

By a neutral atom losing electrons, resulting in more protons than electrons.

What is the significance of noble gas configurations in ions?

Ions achieve electron configurations similar to noble gases, yet retain different atomic numbers.

What is the Aufbau Principle?

Electrons fill the lowest energy orbitals first before moving to higher energy levels.

What is the energy level and how does it relate to the periodic table?

Energy levels correspond to rows on the periodic table, with higher levels being further from the nucleus.

Describe the shape and orientation associated with angular momentum quantum numbers.

They define the shapes of orbitals (s, p, d, f) where electrons are found.

What is the maximum number of electrons that can occupy an orbital?

Two electrons, identified by their spins, one spin up and one spin down.

What does 'noble gases being inert' imply?

Noble gases are largely unreactive and do not easily form chemical compounds.

What was discovered using Hermann von Helmholtz's experiment regarding electron emission?

The emission spectrum and energy levels of electrons.

How do periods in the periodic table relate to energy levels?

Each period corresponds to a principal energy level (n) that the electrons occupy.