Atomic Physics

Democritus Democritus was an Ancient Greek pre-Socratic philosopher primarily remembered today for his formulation of an atomic theory of the universe. Democritus was born in Abdera, Thrace, around 460 BC, although some thought it was 490 BC John Dalton John Dalton FRS was an English chemist, physicist, and meteorologist. He is best known for proposing […]

alpha decay The disintegration of a nucleus into a nucleus of another element with the emission of an alpha particle, which is a helium nucleus. atomic mass The weighed average mass of an atom of the element in naturally occurring samples; given under its symbol in the period table (in atomic mass units, symbolized u). […]

Subtomic Anything smaller than an atom. ( the particles that make up an atom). Nucleus center of atom, contains protons and neutrons. Protons nucleon with a positive charge. mass of one AMU Neutrons nucleon with no charge. mass of one AMU Electron Subatomic particle with a negative charge Electron cloud area around the nucleus where […]

Absorption Line An isolated bright or dark line in a spectrum produced by emission or absorption of light of a single wavelength. Absorption Line Spectrum The electromagnetic spectrum, broken by a specific pattern of dark lines or bands, observed when radiation traverses a particular absorbing medium. The absorption pattern is unique and can be used […]

Atom Contains a positively charged nucleus made of protons and neutrons, surrounded by negatively charged electrons Size of atom Very small with a radius of 0.000000001m Charge of proton +1 Relative mass of proton 1 Charge of electron -1 Relative mass of electron 1/5000 (negligible) Charge of neutron Relative mass of neutron 1 Charge of […]

classical physics development of physics before 1900 modern physics development of physics after 1900 atomic physics to do with the electrons in an atom discrete matter elements would get to a point where they couldn’t be divided anymore (true) idea of continuous matter you can keep dividing elements forever and ever – Aristotle John Dalton […]

strong nuclear force Fundamental force that holds the nucleus together fusion Process in which smaller nuclei combine to f0rm larger ones neutrons Neutral particles in atoms radioactivity Spontaneous process of nuclei changing by emitting particles or rays electrons Negatively charged particles in atoms beta decay Radioactive decay in which electrons are emitted radioactive isotope Specific […]

Anti-Ballistic Missile or National Missile Defense (ABM or NMD) A system with the ability to destroy enemy missiles or their warheads before they hit their targets. This is usually presented as a “defensive” capability, but it is worth noting that this is a counterforce capability Atom A particle of matter indivisible by chemical means. It […]

nucleus dense, positively charged mass in the center of an atom. proton Positively charged subatomic particle found in the nucleus. neutron Neutral subatomic particle found in the nucleus. atomic number number of protons in the nucleus of an atom. mass number sum of the protons and neutrons in the nucleus of an atom. isotope atoms […]

a strong nuclear force Protons and neutrons are held together by what? Atomic number -z- # of protons; defines each element -n- # of neutrons; can vary for each element Mass number -A- Total number of protons -z- and neutrons -n- Isotope the term used to describe different atoms of the same element SAME; DIFFERENT […]

atom basic unit of matter, which consists of a central, positively charged nucleus surrounded by negatively charged electrons Brownian motion the continuous random movement of particles of matter suspended in a liquid or gas cathode-ray tube a vacuum tube containing a source of electrons and a screen to view images planetary model of the atom […]

energy of a photon depends on frequency planks constant the ratio of energy to frequency for a given photon produces photon small packet of electromagnetic energy that has particle-like properties the kinetic energy of a photoelectron depends on wavelength of light in order for a photon to eject an electron from a metal’s surface in […]

Radius of atom 10^-10m Radius of nucleus 1/10000 times smaller than atom radius Isotope Same number of protons, different number of neutrons JJ Thompson Plum pudding model Rutherford and Marsden Nuclear model Bohr Energy levels Chadwick neutrons Unstable isotopes decay randomly and emit radiation Activity of a source how quickly it decays Count – rate […]

a. Democritus The ancient Greek who is known for championing the concept of atom was named ______________. a. Democritus b. Socrates c. Plato d. Zeus d. Thomson Who discovered the electron in 1897? a. Dalton b. Bohr c. Rutherford d. Thomson d. Dalton The “billiard ball model” of the atom is associated with _______. a. […]

Mass defect Difference in mass between the mass of nucleus and mass of separate nucleons Isotopes Isotopes of elements are chemically identical but have different atomic masses Radiative half life The time it takes for the activity to halve Nuclear Binding Energy the energy released when the nuclide is assembled from its individual components Unified […]

proton the nucleus of the simplest atom- hydrogen. It has a positive charge of +q and a mass of m=1.67×10^-27 kg neutron a particle found in the nucleus that is electrically neutral and that has a mass almost identical to the proton. It was discovered in 1932 by James Chadwick, Its charge is q=0, its […]

Atoms Atoms contain a positively charged nucleus made up of protons and neutrons.Which is surrounded by negatively charges electrons. How may the energy level of an electron change? – Absorbing electromagnetic radiation moves electrons to a higher energy level, further from the nucleus. – Electromagnetic radiation is emitted when an electron drops to a lower […]

Atomic/proton number Total number of protons in a nucleus. In an uncharged atom this is the number of electrons too. This determins the chemical properties of the element Nucleon/mass number Total number of protons and neutrons in a nucleus. Since electrons have nearly no mass, it also gives the mass Neutron number Total number of […]

Dalton’s Atomic Theory ~Matter is composed of extremely small particles called atoms. ~Atoms are indivisible and indestructible. ~Atoms of a given element are identical in size, mass, and chemical properties. ~Atoms of a specific element are different from those of another element. ~Different atoms combine in simple whole-number ratios to form compounds. ~In a chemical […]

Atomic number Z, of an atom is the number of protons. (Nuclear charge= Ze Atomic Mass Unit 1.66 X 10^-27 Kg (u) Mass number (A) number of neutrons and protons. Nuclear mass= A (u) Nuclide nucleus of an isotope. Strong nuclear force also called strong force, acts between protons and neutrons that are close together, […]

Absorber Material that prevent radioactive emission from passing through it. ???? Activity Number of radioactive emissions/counts per second- also known as “rate of decay”. ???? Alpha emission Release of alpha particle from, unstable nucleus (A 2+ helium ion or a helium nucleus. ???? Alpha particle The nucleus of a helium atom (two protons and 2 […]