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Matter encompasses all physical substances in the universe, characterized by mass and the occupation of space. At the core of matter are atoms, the smallest whole particles, which are made up of protons, neutrons, and electrons. Early models of the atom, such as Rutherford's and Bohr's, paved the way for the modern electron cloud model, illustrating electrons' probabilistic locations around the nucleus. Understanding atomic structure is key to grasping how matter behaves and interacts, with significant implications for fields ranging from chemistry to physics.
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Matter The term matter describes all of the physical substances around us Matter is anything that has mass and takes up space The Universe is made up of matter and energy
*Matter is made up of atoms.*An atom is the smallest whole particle of matter.* Sub-Atomic particles are smaller than atoms and are the tiny particles that an atom is made of.
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
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
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 • Atomic Mass= the number of protons + the number of neutrons