Chapter 4 Flashcards
(16 cards)
Atom
The smallest unit of an element that maintains the properties of that element
Electron
A subatomic particle that has a negative charge
Nucleus
In physical science, an atoms’s central region, which is made up of protons and neutrons
Electron Clouds
a region around the nucleus of an atom where electrons are most likely to be found
Protron
a stable subatomic particle occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron, but of opposite sign.
Atomic Mass Unit
1/12 the mass of an atom of carbon-12. The carbon-12 (C-12) atom has six protons and six neutrons in its nucleus. In imprecise terms, one AMU is the average of the proton rest mass and the neutron rest mass.
Neutron
a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen.
Atomic Number
the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.
Isotope
each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.
Mass number
the total number of protons and neutrons in a nucleus.
Atomic Mass
the mass of an atom of a chemical element expressed in atomic mass units. It is approximately equivalent to the number of protons and neutrons in the atom (the mass number) or to the average number allowing for the relative abundances of different isotopes.
John Dalton
Elements are made of extremely small particles called atoms. Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties. Atoms cannot be subdivided, created, or destroyed.
Rutherfurd
He discovered alpha and beta rays, set forth the laws of radioactive decay, and identified alpha particles as helium nuclei.
Bohr
Bohr developed the Bohr model of the atom, in which he proposed that energy levels of electrons are discrete and that the electrons revolve in stable orbits around the atomic nucleus but can jump from one energy level (or orbit) to another.
Tompson
discovered the electron in a series of experiments designed to study the nature of electric discharge in a high-vacuum cathode-ray tube, an area being investigated by numerous scientists at the time.
Demoticrus
He developed the concept of the ‘atom’, Greek for ‘indivisible’. Democritus believed that everything in the universe was made up of atoms, which were microscopic and indestructible.
