Atomic Theory (Atomic Structure)

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Across
  1. 4. The sum of the protons and neutrons in the nucleus of an atom. Given alongside an element's name to distinguish between isotopes.
  2. 7. Greek word for atom, meaning "indivisible."
  3. 8. Negatively charged particles found outside an atom's nucleus. In an uncharged atom, the number of electrons is equal to the number of protons. Electrons do not move in fixed paths, but their vague location can be predicted by their energy level.
  4. 9. The number of protons in an atom's nucleus. Also determines what element an atom is.
  5. 12. A fixed distance from an atom's nucleus where atoms with a certain amount of energy may be found. Energy levels closer to the nucleus have less energy and atoms farther from the nucleus have more.
  6. 13. A group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.
  7. 14. Positively charged particles found in an atom's nucleus. All protons are identical, regardless of the element in which they are found. Have a mass of 1.0073 amu.
  8. 16. In an atom, these determine where an electron is likely to be found.
  9. 17. The smallest possible unit of an element that has all of the chemical properties of that element. The fundamental building blocks of life.
  10. 18. Neutrally charged particles found in an atom's nucleus. Like protons, all neutrons are identical. Have a mass of 1.0087 amu.
  11. 19. found within the atom, mainly protons, neutrons, and electrons.
Down
  1. 1. farther from the nucleus.
  2. 2. closer to the nucleus.
  3. 3. Smaller particles that make up protons and neutrons. All nuclear particles are thought to be combinations of three quarks.
  4. 5. Often abbreviated to "amu." Because atoms are so small, scientists use this special unit to measure their mass.
  5. 6. Atoms of the same element that have the same number of protons but different numbers of neutrons.
  6. 10. A notation of one or two letters representing a chemical element. For example, the chemical symbol of Hydrogen is H.
  7. 11. A region around the nucleus of an atom where electrons are likely to be found.
  8. 15. A substance that can not be broken down into simpler substances by chemical means and is made up of atoms that all have an identical number of protons.
  9. 18. The core of an atom, in the center. It has 99.9 percent of an atom's mass.