Exam Review

Exam Review - Exam Review Structure &amp; Properties Unit x...

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Exam Review x Atomic Theories: Dalton: Matter is composed of indestructible, indivisible atoms, which are identical for one element, but different from other elements. Thomson: Matter is composed of atoms that contain electrons (negative particles) embedded in a positive material. The kind of element is characterized by the number of electrons in the atom. Rutherford: An atom is composed of a very tiny nucleus, which contains positive charges and most of the mass of an atom. Very small negative electrons occupy most of the volume of the atom. Rutherford Model: An atom is made up of an equal number of negatively charged electrons and positively charged protons. Most of the mass of atom and all of its positive charge is contained in a tiny core region called the nucleus. The nucleus contains protons and neutrons that have approximately the same mass. The number of protons is called the atomic number. The total number of protons and neutrons is called the mass number. Proton: a positively charged subatomic particle found in the nucleus of atoms. Isotopes: a variety of atoms of an element; atoms of this variety have the same number of protons as all atoms of the element, but a different number of neutrons. Neutron: a neutral (uncharged) subatomic particle present in the nucleus of atoms. Atoms are composed of protons, neutrons, and electrons. Atoms of the same element have the same number of protons and electrons, but may have a varying number of neutrons (isotopes of the element). x Quantum Theory The wave of light was established around 1900. Radiation beyond the limits of the visible region of the spectrum was shown to have some relationship between frequency, wave length and the speed of light. The speed of light (electromagnetic radiation) in a vacuum is a fundamental constant: 3.00 x 10 8 m/s Wavelength vs. Frequency C = fλ Quantum Theory C = speed of the wave (m/s) F = frequency (MHz) λ = wavelength (m) 1) Atoms can only absorb or emit energy in discrete amounts called quanta (packets) x quantum 2) Energy of each quanta is proportional to frequency of radiation E = hf E = energy of a quantum of light f = frequency h = Planck’s constant – a fundamental constant of matter (6.63 x 10 -34 Joules – seconds) Max Planck (1858 – 1947) started the quantum revolution. Planck’s hypothesis is that light emitted by a hot solid is quantized and can only be transferred in discrete packets called photons. Photoelectric Effect

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James Maxwell proposed that light is an electromagnetic wave composed of electric and magnetic fields that can exert forces on charged particles. Light is an electromagnetic wave consisting of continuous series of wavelengths. The photoelectric effect is the release of electrons from a substance due to light striking the surface of a metal. x
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Exam Review - Exam Review Structure &amp; Properties Unit x...

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