Matter The term matter describes all of the physical substances around us: your table, your body, a pencil, water, and so forth
Matter • Anything that has mass and takes up space (has volume) • Includes all things that can be seen, tasted, smelled, or touched • Does not include heat, sound, or light
Models Models are often used for things that are too small or too large to be observed or that are too difficult to be understood easily
Models • In the case of atoms, scientists use large models to explain something that is very small • Models of the atom were used to explain data or facts that were gathered experimentally. • So, these models are also theories
Early Models of the AtomDemocritus • Universe was made of empty space and tiny bits of stuff • Called these tiny bits of stuff atomos • Atoms could not be divided
Early Models of the AtomLavoisier • Demonstrated that burning wood caused no change in mass • Law of Conservation of Matter
Early Models of the AtomDalton • All elements are composed of indivisible particles. • Atoms of the same element are the same • Atoms of different elements are different. • Compounds consisted of atoms of different elements combined together
Early Models of the AtomThomson • Plum pudding model • Atom made of a positively charged material with the negatively charged electrons scattered through it.
Early Models of the AtomRutherford • Mostly empty space • Small, positive nucleus • Contained protons • Negative electrons scattered around the outside
Early Models of the AtomBohr • Electrons move in definite orbits around the nucleus
Early Models of the AtomChadwick • Discovered the neutron
Modern Model of the AtomThe electron cloud • Sometimes called the wave model • Spherical cloud of varying density • Varying density shows where an electron is more or less likely to be
A closer look at quantum mechanics: http://www.fearofphysics.com/Atom/atom1.html
Atoms Family Album • In the center of Matterville, there is a place called the Nucleus Arcade, where two members of the Atoms Family like to hang out. Perky Patty Proton, like her sisters, is quite large with a huge smile and eyes that sparkle (+). Patty is always happy and has a very positive personality. Nerdy Nelda Neutron is large like Patty, but she has a boring, flat mouth and eyes with zero expression (o). Her family is very apathetic and neutral about everything. Patty, Nelda, and their sisters spend all their time at the arcade. + + Patty Proton Nelda Neutron
Atoms Family Album • Around the Nucleus Arcade, you will find a series of roadways that are used by another member of the Atoms Family, Enraged Elliott Electron. Elliott races madly around the Arcade on his bright red chrome plated Harley-Davidson. He rides so fast that no one can be sure where he is at any time. Elliott is much smaller than Patty and Nelda and he is always angry because these bigger relatives will not let him in the Arcade. He has a frown on his face, eyes that are squinted with anger, and a very negative (-) attitude. Elliot Electron
Atoms Family Album • The first energy street can only hold only two Electron brothers. The second energy street, called the Energy Freeway, can hold 8 brothers. The third energy street, called the Energy Superhighway, can hold 18 of the brothers.
Atomic Structure • Nucleus • Protons • Neutrons • Electrons
Atomic Structure • Electrons • Tiny, very light particles • Have a negative electrical charge (-) • Move around the outside of the nucleus
Atomic Structure • Protons • Much larger and heavier than electrons • Protons have a positive charge (+) • Located in the nucleus of the atom
Atomic Structure • Neutrons • Large and heavy like protons • Neutrons have no electrical charge • Located in the nucleus of the atom
Describing Atoms • Atomic Number = number of protons • In a neutral atom, the # of protons = the # of electrons
Describing Atoms • Atomic Mass Number - equal to the number of protons plus neutrons.
Describing Atoms • Atomic Weight - average mass of the naturally occurring isotopes of an element .