What information is gained from knowing an atoms atomic number the number of protons in the nucleus and the number of electrons in a neutral atom How does atomic mass differ from average atomic mass atomic mass is the sum of the number of protons and neutrons in the atom. Read more…
Activity The number of nuclei of a sample that decay per second. Its unit is the becquerel, Bq Alpha decay A type of radiactive decay in which an alpha particle is given out from a decaying nucleus Alpha particle A positively charge particle made up of two protons and two Read more…
Dalton’s theory He composed the theory that all matter is composed of extremely small particles called atoms, that cannot be divided Thomson’s model He came up with the model in which atoms were made up of positively charged substances with negatively charged electrons scattered about. Also called the “plum pudding Read more…
Atomos greek word for atom- means not able to be divided Democritus Greek philosopher who developed an atomistic theory of matter (460-370 BC) atom (physics and chemistry) the smallest component of an element having the chemical properties of the element Dalton’s Atomic Theory 1) elements are composed of atoms. 2) Read more…
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 Read more…
J. J. Thomson discovered the electron Robert Millikan calculated the mass of the electron Eugen Goldstein first observed the proton, but he didn’t know what it was at the time James Chadwick discovered the neutron Ernest Rutherford Got a surprise when he found the atom is mostly empty space with Read more…
Atoms The smallest particle of an element that can enter into a chemical combo Electrons Negatively charged subatomic particles Quantum A discrete amount “packet” Photoelectric effect The emission of electrons that occurs when certain metals are exposed to light. Photon A “particle” of electromagnetic energy Dual nature of light Light Read more…
Fnet*t=mv-mv0 law of impulse and momentum Vector Impulse V or S Vector Momentum V or S Kgm/s or N*s SI units for Impulse and Momentum Momentum Sum of individual momenta Conserved Total momentum is m1v1+m2v2=m1v1’+m2v2′ Law of elastic collision m1v1+m2v2=v'(m1+m2) Law of inelastic collision m1v1’=m2v2′ Law when both objects have Read more…
Atom The smallest quantity of an element that can take part in a chemical reaction, consisting of a positively charged nucleus made up of protons and neutrons, surrounded by negatively charged electrons Nucleus The positively charged, dense region at the centre of an atom, made up of protons and neutrons, Read more…
Plum Pudding Model After the discovery of electrons, the theory of atoms by which electrons are located in a sea of dispersed positive charge Sub-Atomic Particles The fundamental particles; protons, neutrons and electrons Nucleus The central part of the atom containing protons and neutrons Nucleons The sub-atomic particles within the Read more…
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 Read more…
Alpha particle Made of 2 protons and 2 neutrons Atomic number The number of protons in an atom Becquerel An emission of one particle per second from an unstable nucleus Beta particle A fast moving electron emitted from the nucleus of an atom Contamination The unwanted presence of radioactive atoms Read more…
nuclear power energy from splitting Uranium atoms. digital camera a camera that takes and stores photographs as digital files radiation therapy A cancer treatment in which cancer cells are irradiated to kill them and stop their growth. nuclear force an attractive force that acts between all nuclear particles that are Read more…
Proton has a positive charge and mass around 1 amu Neutron no charge and mass around 1 amu Electron a negative charge and negligible mass Nucleus contains the protons and neutrons, while the electrons move around the nucleus Atomic number the number of protons in a given element Mass number Read more…
Who believed the atom was a solid sphere? Democritus What 3 things did Democritus propose about the atom? – Matter can not be divided , cannot be cut(atomos) – Small hard particles, that are made of the same material but are different shapes and sizes – They are always moving Read more…
Nucleus The nucleus of an atom is the solid center of the atom. most of the mass of an atom is concentrated in the nucleus. Electron An electron is a negatively charged particle found around the nucleus of the atom. Nucleon A nucleon is the collective name for the particles Read more…
What is blackbody radiation? electromagnetic waves reflected off a blackbody What is a blackbody? object that has absorbed almost all electromagnetic waves What is an example of a blackbody? black hole What is ultraviolet catastrophe? failed prediction of classical physics that the energy radiated by a blackbody at extremely short Read more…
Introduction Light it wave-like. Photoelectric Effect Light shining on various metal surfaces cause electrons to be ejected from the surfaces. Birth of Quantum Theory Developed in 20th century by Mark Planck. Energy only occurs in small amounts called quanta. (Explains nuclear and radiaiton phenomena). E=hf-W Wave-Particle Duality The concept that Read more…
Atom All substances are made from particles called atoms Element An element contains only one type of atom 90 elements occur naturally, the rest are man made. Compounds Are substances when two or more different elements are chemically joined together. Mixture Is a substance, when two or more different elements Read more…
atom Atoms are small particles from which all substances are made. They are the smallest neutral part of an element that can take part in chemical reactions. electron Tiny particle with a negative charge that is found in shells around the nucleus of an atom. electron shell Area around a Read more…