Matter - anything that occupies space and has mass
Atoms - they compose matter
Atoms - smallest identifiable unit of an element
Leucippus and Democritus - they theorized that matter was ultimately composed of small, indivisible particles
Democritus - he coined the term “atomos”
Antoine Lavoisier - he established the “Law of Conservation of Mass”
Law of Conservation of Mass - “In a chemical reaction, matter cannot be created or destroyed, only rearranged.“
Joseph Proust - he proposed the “Law of Definite Proportions”
Law of Definite Proportions - “Different samples of the same element always contain its constituent elements in the same proportion by mass.”
John Dalton - he formalized the Atomic Theory
Wilhelm Rontgen - he discovered a type of radiation which he termed X-ray when he was studying vacuum tubes and cathode rays
Henri Becquerel - he discovered the spontaneous emission of radiation from Uranium ores
Marie Curie - she coined the term “radioactivity” for the observed spontaneous radiation
Joseph John Thomson - he discovered the first subatomic particle—electrons, by investigating cathode rays in a vacuum tube
Ernest Rutherford - he demonstrated that there were at least two distinct types of radiation
Alpha and beta radiation - two distinct types of radiation
Hans Geiger - he was Rutherford’s associate in which they proved that α particles are He 2+ ions.
1927 Solvay Conference - the birth of Quantum Mechanics
Max Planck - he proposed the quantization of energy of light to produce a practical solution to the unexplained Blackbody radiation
Albert Einstein - he provided the theoretical background for the Photoelectric Effect
Photoelectric Effect - a phenomenon where electrons are emitted from a plate when exposed to light
Robert Millikan - he succeeded in precisely determining the magnitude of the electron’s charge
Ernest Rutherford, Hans Geiger, and Ernest Marsden - they used α particles to bombard very thin gold foils and discovered protons
James Chadwick - he discovered neutrons
Protons - positive charge
Electrons - negative charge
Neutrons - no charge
Unified atomic mass - defined as 1/12 of the mass of a carbon atom containing 6 protons and 6 neutrons
Nucleus - location of protons and neutrons
Nucleus - dense core of the atom
Nucleus - location of most of the atom’s mass
Electron cloud - location of electrons
Electron cloud - comprises most of the atom’s volume
Electron cloud - mostly an empty space
Element - a pure substance that cannot be broken down into simpler substances by a chemical reaction
Atomic number - it states the number of protons of an element
Z - symbol for atomic number
Julius Lothar Meyer - he created the Periodic Table of Elements similar to Dmitri Mendeleev’s work
Clemens Winkler - discovered eka-silicon
Eka-silicon - modernly known as Germanium
Alkali metals - soft and shiny metals with low melting points
Alkaline earth metals - good conductors of heat and electricity, as well as reacts with water to form basic solutions
Halogens - very reactive and exist as two atoms joined together
Noble gases - very stable and rarely combine with other elements
Isotopes - the term for atoms with the same number of protons but different numbers of neutrons
Werner Heisenberg - a German physicist who formulated the Quantum Theory
Schrodinger equation - a wave equation formulated by Erwin Schrodinger to describe the electronic structure of atoms
Quantum Numbers - numerical labels used to describe the most probable location of electrons in an atom
s-orbital - has a spherical shape
p-orbital - has a dumbbell shape
Electron configuration - shows how the electrons are arranged in an atom’s orbitals
Ground state - the lowest energy arrangement
Aufbau Principle - “As protons are added one by one to the nucleus to build up the elements, electrons are similarly added to the atomic orbitals.
Pauli Exclusion Principle - “No two electrons can be/have the same set of four quantum numbers”
Hunds Rule - “The most stable arrangement of electrons in subshells is one with the greatest number of parallel spins”
Valence electrons - electrons in the outermost shell
Valence shell - it is the outermost shell
Periodic trends - specific patterns that are present in the periodic table that illustrate different aspects of a certain element
Atomic radius - one-half the distance between the two nuclei in two adjacent atoms
Ionic radius - radius of a cation or anion
Ionization energy - the energy required to remove the most loosely held electron from an atom in the gaseous state
Electron affinity - the energy change that occurs when an electron is accepted by an atom in the gaseous state
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