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…
democritus all matter is made out of tiny, indivisible particles (atomos). no experimentation, no explanation of chemical behavior. aristotle did not believe in atoms. All matter is continuous, composed of air, water, fire and earth. his;refs weren’t challenged until the age of experimentation in the 18th century. john dalton proposed Read more…
Nuclide A particular type of atom or nucleus determined by its proton (atomic) number and its nucleon number / number of protons and number of neutrons Nucleon A proton or neutron Isotopes The nuclei of different isotopes of an element have the same number of protons but different numbers of Read more…
atom The smallest particle of an element that can enter into a chemical combination electrons negatively charged subatomic particles quantum a discrete amount of energy 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 Read more…
3 Phenomena Blackbody radiation , the photoelectric effect, and atomic spectra. p.265 Blackbody Radiation states that a perfectly “black” body one that would absorb all light and other EM radiation incident upon it would also be a perfect emitter of EM radiation. Blackbody was said to emit blackbody radiation (BBR). 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…
Plum Pudding Model Sphere of positive charge with electrons stuck in it Isotope Atom with a different number of neutrons from its element on the periodic table Ionising Radiation Takes electrons from atoms Alpha 2 neutrons and 2 protons. Travels a few cm in air and stopped by paper Beta Read more…
Size of atoms: Very small, radius is around 1 x 10⁻¹⁰ metres What is the basic structure of an atom? A positively charged nucleus composed of both protons and neutrons surrounded by negatively charged electrons How big is the radius of a nucleus compared to the radius of an atom? Read more…
Alpha decay the radioactive decay process in which the nucleus of an atom emits an alpha (helium) particle Beta decay occurs when a nucleus has too many neutrons for the protons present, a neutron converts to a proton, a negative electron is released, and an antineutrino is released Gamma radiation Read more…
The Atomic Hypothesis The idea of matter: first thought by Aristotle to be a combination of the four elements- earth, air, fire, water. Thought to be composed of atoms by Greeks from the 5th century BC. Further proposed as atoms in 1800s by meteorologist and schoolteacher John Dalton. Robert Brown Read more…
What is the proton Number and prefix for it? The number of protons in a nuclide Z What is the Nucleon number and prefix for it? The number of protons + neutrons A How do you find the number of neutrons in a nucleus? N= A – Z What is Read more…
John Dalton’s model All matter is made up of atoms. They are the smallest particles of matter and cannot be broken into smaller units. Joseph Thomson’s model (Cathode ray experiment) There are negative electrons. The overall charge of an atom is neutral. Plum pudding model – Negatively charged electrons are Read more…
Nuclide Specific atomic structure (protons + neutrons) Nucleon A Nuclear Particle (protons or neutrons) Isotope Two atoms of the same element with a different atomic mass Nuclear Transmutation Nuclear Reaction in which one nuclide is changed into another nuclide (Fusion or Fission) Photon Particle of light Ionization The process of Read more…
What determines the atomic number? The number of protons What determines the mass number? No. neutrons + no. protons Define the term ion An atom with either more or less electrons than protons Define the term isotopes Different forms of an element with the same number of protons but a Read more…
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…