Subatomic Particles and Isotopes ©2011 University of Illinois Board of Trustees

Properties of subatomic particles. NameSymbolCharge (C) Common Charge Mass (kg) Location Electrone-e x x Outside nucleus Protonp+p x x Nucleus Neutronn0n0 0 (neutral) x Nucleus ©2011 University of Illinois Board of Trustees

Four Basic Forces in Nature There are 4 forces in nature that effect all matter in the universe. (Remember - a force is a push or a pull) 1.Strong Force – strongest force but has the shortest reach. It is responsible for holding the nucleus of an atom together. 2.Weak Force – next strongest force. It is responsible for radioactive decay. 3.Electromagnetic Force – the force of attraction or repulsion between charged objects or poled objects. Most important force in the study of chemistry 4.Gravity – weakest force but has the longest reach. It is a force of attraction between any two objects in the universe. ©2011 University of Illinois Board of Trustees

Grand Unified Force Shortly after the Big Bang, all 4 forces were thought to be one force dubbed the Grand Unified Force. As the universe cooled the forces began to separate. Three of the 4 forces have been shown to be part of one force. Even though Einstein spent the last 20+ years of his life trying to work in gravity, it still hasn’t been shown to be part of a Grand Unified Force. ©2011 University of Illinois Board of Trustees

Rutherford Model Other Subatomic Particles ©2011 University of Illinois Board of Trustees

An artist's impression of the shower of subatomic particles produced when a cosmic ray proton collides with the top of the earth's atmosphere. Electronic signatures produced by collisions of protons and antiprotons in the Tevatron accelerator at Fermilab provided evidence that the elusive subatomic particle known as top quark has been found. %20collisions/egosumebrius/CDF-Top.jpg ©2011 University of Illinois Board of Trustees

Quarks, photons, gluons—physicists understand their characteristics, but didn't know what they may look like. That is until Jan-Henrik Andersen translated the physical properties of subatomic particles to images on paper and canvas. ©2011 University of Illinois Board of Trustees

Coulomb’s Law (p. 83) The most important of the four forces in chemistry is the electromagnetic forces Coulomb’s Law, which describes the force of attraction or repulsion between charged objects, is one of the most important laws in chemistry. Coulomb’s Law states that the force of attraction or repulsion between charged particles directly depends on the amount of charge on the particles and inversely depends on the square of the distance that separates the particles. ©2011 University of Illinois Board of Trustees

Coulomb’s Law The greater the charge on the particles, the greater the force of attraction or repulsion. –Remember – opposite charges attract and like charges repel. The closer the charged particles are to each other, great the force. Coulomb’s law in formula form: F electric = K c q 1 q 2 D 2 Where K c = Coulomb’s Constant Kc = x 10 9 N m 2 /C 2 q 1 and q 2 are the charges on the objects D is the distance that separates the charges. ©2011 University of Illinois Board of Trustees

Which has the greatest force between the particles? + A. B. C. D _ _ _ _ _ _ Answer: B ©2011 University of Illinois Board of Trustees

Atomic Number and Mass Number Atomic Number is the number of protons in the nucleus. –All atoms of the same element have the same atomic number. Mass number is the number of protons plus the number of neutrons in the nucleus. –Atoms of the same element can have different mass numbers because the number of neutrons can be different. Atoms of the same element with different mass numbers are called isotopes.If an isotope is radioactive, sometimes it is referred to as a radioisotope. ©2011 University of Illinois Board of Trustees

Isotopes The symbol for isotopes uses the element symbol and superscript on the left for mass number and subscript on the left for atomic number. –Example: –Sometimes the isotope is written with just the mass number: He-3 Note mass number – atomic number = Number of neutrons ©2011 University of Illinois Board of Trustees