Warm Up • What is an electron? Where is located in an atom? • What is a proton? Where is it located in an atom?
Atoms • What are the parts in an Atom?
Electrons • Electrons are present in the region of space outside the nucleus. • They are negatively charged and weakly bound to the atom. • They are loosey goosey and float from one atom to the next • They like to party
Protons and Neutrons • The nucleus of the atom contains positively charged protons and neutral neutrons. • They are in the center of the atom. • The protons and neutrons will remain within the nucleus of the atom. • They like to stay at home and watch Netflix. • THEY NEVER LEAVE THEIR HOME
Charges at Rest Charge • there are two kinds of charge, positive and negative • positive charge comes from having more protons than electrons • negative charge comes from having more electrons than protons
Charge Interactions • Opposite charges repel • Same charges attract
Sames Repel • “Why do you look at the speck of sawdust in your brother’s eye and pay no attention to the plank in your own eye?”
Electrostatic charging • Materials are divided into three categories, depending on how easily they will allow charge (i.e., electrons) to flow along them. These are: • conductors • insulators • semi-conductors
Conductors • the outermost electrons in the atoms are so loosely bound to their atoms that they’re free to travel around. metals, for example
Insulators • In insulators, on the other hand, the electrons are much more tightly bound to the atoms, and are not free to flow, rubber, wood, plastic for example
Semi-Conductors - • In between conductor and insulator • silicon is a good example
Three ways that objects can be given a net charge • Charging by friction • Charging by conduction • Charging by induction
Friction • this is useful for charging insulators. • rub one material with another • Electrons transfer from one material to the other. • For example, rubbing glass with silk or saran wrap generally leaves the glass with a positive charge; rubbing PVC rod with fur generally gives the rod a negative charge.
Conduction • useful for charging metals and other conductors. • If a charged object touches a conductor • charging the conductor with the same sign as the charge on the object
Induction • also useful for conductors. • a charged object is brought close to the conductor, and does not touch it. • If the conductor is connected to ground (ground is basically anything neutral that can give up electrons to, or take electrons from, an object), • electrons will either flow on to it or away from it. • When the ground connection is removed , the conductor will have a charge opposite in sign to that of the charged object
Polarization • is the process of separating opposite charges within an object