Structure of Matter and Atomic Theory

Flashcards covering key concepts in atomic theory, structure of matter, and associated scientific principles.

Atomic Theory

Proposed by John Dalton, it states that all matter is composed of subunits called atoms.

Elements

Different identities of atoms that combine in definite ratios to form compounds.

J.J. Thompson

Discovered electrons and proposed the 'plum pudding model' of the atom.

Plum Pudding Model

Model by J.J. Thompson suggesting atoms consist of positive and negative charges distributed throughout.

Robert Milliken

Conducted the oil drop experiment to determine the charge to mass ratio of electrons.

Ernest Rutherford

Fired alpha particles at gold foil and concluded that atoms have a small, dense, positively charged nucleus.

Max Planck

Determined that electromagnetic energy is quantized and introduced Planck's constant.

Bohr Model

Model showing that electrons exist at fixed distances around the nucleus, applicable only for one electron atoms.

De Broglie Wavelength

Equation showing that particles with momentum possess wave characteristics, Wavelength = h / mv.

Heisenberg Uncertainty Principle

States that it's impossible to know both the position and momentum of an electron simultaneously.

Schrodinger Equation

Describes the wave function of electrons in atoms and their probabilistic locations.

Atomic Mass

The total mass of an atom, calculated from the combined mass of protons and neutrons.

Isotopes

Atoms of the same element with the same number of protons but different numbers of neutrons.

Ionic Bonding

Occurs between atoms with a significant difference in electronegativity, resulting in electron transfer.

Covalent Bonding

Occurs when atoms share electrons, usually between nonmetals.

Polar Covalent Bond

When the difference in electronegativity leads to uneven sharing of electrons between atoms.

Van der Waals Forces

Weak intermolecular forces arising from temporary dipoles due to electron movement.

Hydrogen Bond

A strong polar attraction between a hydrogen atom bonded to an electronegative atom and another electronegative atom.

Alpha Decay

Radioactive decay where an alpha particle (2 protons, 2 neutrons) is emitted from the nucleus.

Half-Life

The time required for half of a sample of a radioactive substance to decay.

Quantum Numbers

Set of four numbers that describe the unique properties of electrons in atoms.

Lewis Structures

Diagrams showing the arrangement of valence electrons around atoms in a molecule.

Electronegativity

Measure of the ability of an atom in a covalent bond to pull electron toward itself.

Dipole

Measure of the separation of positive and negative charges in a polar molecule.

Mole

A unit used to describe the amount of substance present in exactly 12 g of carbon-12: equivalent yo 6.002 × 10^-23 particles

Molar Mass

The mass of one mole of a substance, typically expressed in grams per mole (g/mol), calculated from the sum of the atomic masses of its constituent elements.

Molality

The concentration of a solution expressed as the number of moles of solute per kilogram of solvent.

Molecular Formula

A chemical formula that shows the number and types of atoms in a molecule, representing the actual number of each type of atom present. For example, C2H6 represents two carbon atoms and six hydrogen atoms.

Octet Rule

Atoms gain, lose, or share electrons in order, or share to achieve a full outer shell of eight electrons, leading to increased stability (filled s- and p-shells).

Pi Bond

Bond resulting from the overlap of unhybridized orbitals: additional bond between two attoms that is formed following the formation of a sigma bond.

Sigma Bond

Covalent bond resulting the overlap of orbitals along the internuclear axis.

Quantized

Refers to the notion that certain properties, such as energy, can only take on discrete values rather than a continuous range. Indicating that energy levels in atoms are not continuous, but rather quantized into specific levels.