Chemistry Test

Aristotle's composition of matter qualities

Hot, Cold, Moist, Dry

Democritus's theory of matter

Matter is made up of building blocks called atoms.

Lavoisier's law of conservation of mass

Energy cannot be created or destroyed; total mass remains constant in chemical reactions.

Proust's law of definite proportions

Elements combine in definite mass ratios to form compounds.

Dalton's Atomic Theory

1. Each element consists of indivisible atoms; 2. Atoms cannot be created nor destroyed; 3. All atoms of a given element are identical; 4. Atoms combine in definite whole number ratios; 5. Atoms of different elements have different masses.

Thomson's Cathode Ray Experiment

Discovered negative particles later named electrons.

Plum Pudding Model

Thomson's model of the atom where electrons are distributed in a positive 'soup'.

Radioactivity

Spontaneous changes in an atom's nucleus creating a different nuclide.

Radiation

Energy released as particles or rays in radioactive decay.

Alpha particles

The largest type of radiation, positively charged, referred to as a helium nucleus.

Rutherford's Gold Foil Experiment

Used alpha particles to reveal the nuclear model of the atom.

Nuclear model of the atom

Atom consists of a dense, positively charged nucleus surrounded by a diffuse negative charge.

Canal Rays

Positive particles demonstrated by Eugen Goldstein in the Canal Ray Experiment.

Proton discovery

Credited to Ernest Rutherford in 1917.

Neutron discovery

Discovered by Sir James Chadwick in 1932.

Bohr's planetary model of the atom

Protons and neutrons in the nucleus, electrons in shells surrounding the nucleus.

Heisenberg Uncertainty Principle

It is impossible to know both the exact position and momentum of an object simultaneously.

Quantum mechanical model of the atom

Developed from Schrodinger’s equation, providing a probabilistic model of electron location.

Aufbau Procedure

Method of obtaining ground state configurations by filling lower energy orbitals first.

Pauli Exclusion Principle

No two electrons in an atom can have the same set of four quantum numbers.

Hund's Rule

For degenerate orbitals, the lowest energy state occurs when the number of electrons with the same spin is maximized.

Valence Rule

Valence electrons in the highest energy levels are involved in chemical reactions and bonding.

Exception to the Rule

Only applies to d and f subshells due to closeness in energy to the previous subshell.