Video Notes: Atomic History, Bohr Model & Periodic Table (Vocabulary)

A set of vocabulary flashcards covering key terms and definitions from the lecture notes on atomic history, the Bohr model, and the periodic table.

Aristotle

Ancient philosopher who proposed the four elements (air, water, fire, earth) and did not believe in atoms.

Democritus

Early philosopher who proposed that matter is made of tiny indivisible particles called atomos.

Dalton

Proposed the modern atomic theory: matter is made of atoms; atoms of the same element are identical; atoms combine in fixed ratios.

Atom

The basic unit of matter; building block of elements; considered indivisible in early theories and the source of all matter.

Plum Pudding Model

Thomson’s model of the atom: a positively charged 'soup' with embedded electrons.

Cathode Ray Tube (CRT)

Vacuum tube used to study cathode rays; led to the discovery of electrons by deflecting beams with electric and magnetic fields.

Electron

Negatively charged subatomic particle discovered via the CRT.

J. J. Thomson

Scientist who discovered the electron and proposed the Plum Pudding Model.

Gold Foil Experiment

Rutherford’s experiment showing a dense, positively charged nucleus; most alpha particles pass through; some are deflected.

Nucleus

Dense, positively charged center of the atom containing protons and neutrons.

Proton

Positively charged subatomic particle in the nucleus; contributes to the nucleus’s positive charge.

Neutron

Electrically neutral subatomic particle in the nucleus.

Ernest Rutherford

Scientist who proposed the nuclear model after the gold foil experiment; discovered the nucleus and protons.

Bequerel

Scientist who discovered radioactivity.

Marie Curie

Scientist who studied radioactivity and characterized radioactive elements.

Pierre Curie

Collaborator with Marie Curie in the study of radioactivity.

Radioactivity

Emission of radiation from unstable nuclei.

Canal rays

Positive rays observed by Goldstein; related to protons.

Bohr Model

Atomic model with electrons in fixed, quantized energy levels; electrons jump between levels by absorbing or emitting energy.

Quantized energy levels

Electrons occupy specific energy shells; transitions involve discrete energy amounts.

Absorption

Electron gains energy to move to a higher energy level.

Emission

Electron loses energy by moving to a lower energy level, releasing a photon.

Spectrum

Element-specific colors produced by electron transitions (emission) or absorption of light.

Mendeleev

Dmitri Mendeleev, father of the periodic table; organized elements and predicted missing ones.

Periodic Table

Organizes elements by atomic number and properties; periods are rows, groups are columns.

Period

Horizontal row in the periodic table.

Group (family)

Vertical column in the periodic table; elements share similar properties.

Alkali Metals

Group 1 metals; soft, highly reactive; form soluble oxides/salts.

Alkaline Earth Metals

Group 2 metals; solids; reactive; form insoluble bases and oxides.

Halogens

Group 17 nonmetals; diatomic; highly reactive; form salts with metals.

Noble Gases

Group 18 inert gases; very unreactive and stable as monatomic atoms.

Transition Metals

D-block elements; variable oxidation states; good conductors.

Ionization Energy (IE1)

Energy required to remove one valence electron from a neutral atom.

Electron Affinity

Energy change when a neutral atom gains an electron; noble gases are exceptions.

Effective Nuclear Charge

Net positive pull felt by valence electrons; increases across a period.

Shielding

Inner electrons block some nuclear pull from outer electrons; effect increases down a group.

Atomic Radius

Size of an atom; increases down a group, decreases across a period.

Cation

Positively charged ion formed when metals lose electrons.

Anion

Negatively charged ion formed when nonmetals gain electrons.

Ionic Charge

Overall charge on an ion after electron transfer.

Mass Spectrometer

Instrument that measures masses and abundances of isotopes by ionizing, accelerating, bending, and detecting ions.

Isotope

Atoms of the same element with different numbers of neutrons; different mass but similar chemistry.

Average Atomic Mass

Weighted average of isotopic masses based on their natural abundances.

Isotopic Abundance

Proportion of each isotope of an element found in nature.

Lewis Dot Diagram

Diagram showing valence electrons as dots around the element symbol.

Bohr–Rutherford Diagram

Diagram combining Bohr’s electron shells with Rutherford’s nucleus to show electrons around a nucleus.

Radioisotope

Isotope that is unstable and decays, emitting radiation.

D spectroscopy/Spectroscopy

Study of emission/absorption spectra to identify elements and transitions.