Atomic History and Trends

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Across
  1. 4. An ion that has a positive charge
  2. 7. Sublevel energy levels contained within a principal energy level
  3. 8. Model Model of the atom that describes electrons as traveling in fixed, circular paths—called energy levels or shells—around a central nucleus, much like planets orbiting the sun.
  4. 9. An ion that has a negative charge
  5. 15. Atom An atom that has no net electrical charge
  6. 16. a pure substance that is made up of one type of atom
  7. 18. (atomic) The quantity of matter contained in an atom of an element, measured in atomic mass units (amu)
  8. 19. A mathematical wave function that describes the wave-like behavior of an electron in an atom or molecule
  9. 20. Law Describes a relationship in nature that is supported by many experiments
  10. 21. A non-charged (neutral) subatomic particle found in the nucleus of an atom, the mass is 1 atomic mass unit (amu); determines the isotope of an element
  11. 24. The smallest fundamental unit of matter that retains the chemical properties of a specific substance
  12. 27. Theory A theory of the nature of matter: all material substances are composed of minute particles or atoms of a comparatively small number of kinds and all the atoms of the same kind are uniform in size, weight, and other properties
  13. 28. Mechanical Model Atomic model in which electrons are treated as waves; also called the wave mechanical model of the atom
  14. 29. Theory Highly reliable, well established explanation of a natural or physical phenomenon
Down
  1. 1. Composition The percentage of a sample that is composed of each isotope of an element
  2. 2. Atomic Mass The average mass of all isotopes of an element, given on the periodic table
  3. 3. The shortest distance between equivalent points on a continuous wave; is usually expressed in meters,centimeters, or nanometers.
  4. 5. Atoms of the same element with different numbers of neutrons
  5. 6. Experiment A classic chemistry/physics experiment where positively charged alpha particles were shot at an ultra-thin sheet of gold foil. The unexpected way the particles scattered proved that atoms are not solid spheres, leading directly to the discovery of the atomic nucleus.
  6. 10. The positively charged center of an atom, composed of neutrons and protons, and possessing most of the mass but occupying only a small fraction of the volume of the atom
  7. 11. Detectable events that are observed through the senses or technology; can be explained through scientific laws, ideas, principles, and theories
  8. 12. Charge A physical property of matter that causes matter to experience a force when placed in an electromagnetic field, can be positive or negative; like charges repel each other and unlike charges attract each other
  9. 13. Ray Radiation that originates from the cathode and travels to the anode of a cathode-ray tube
  10. 14. a negatively charged subatomic particle that can be either free (not attached to any atom) or bound to the nucleus of an atom and has negligible mass; determines the chemical reactivity of an element
  11. 17. Particle Any unit of matter smaller than an atom
  12. 22. A positively charged subatomic particle found in the nucleus of an atom, the mass is 1 atomic mass unit (amu); determines the identity of an element
  13. 23. The product of an object's mass and its velocity
  14. 25. Cloud the system of electrons surrounding the nucleus of an atom
  15. 26. Principle A broadly accepted, fundamental truth or rule derived from empirical observations
  16. 27. The smallest particle of an element that retains all the properties of that element; is electrically neutral, spherically shaped, and composed of electrons, protons, and neutrons