Across
- 3. each of more than one hundred substances that cannot be chemically interconverted or broken down into simpler substances and are primary constituents of matter. Each element is distinguished by its atomic number, i.e. the number of protons in the nuclei of its atoms.
- 5. the positively charged central core of an atom, consisting of protons and neutrons and containing nearly all its mass.
- 7. a stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary carrier of electricity in solids.
- 8. physical region or space where the electron is most likely to be present
- 13. a subatomic particle of a class that is thought to bind quarks together.
- 15. cloud model: Most current model of the atom, Electron cloud model is used to describe where electrons are when they go around the nucleus of an atom.
- 17. a positively charged ion, usually formed after an atom loses one or more electrons.
- 21. Atomic Theory: Dalton's atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass.
- 22. number: the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.
- 25. a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen.
Down
- 1. particles: a subatomic particle with no sub-structure, not composed of other, smaller particles.
- 2. a stable subatomic particle occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron, but of opposite sign.
- 4. any of a number of subatomic particles carrying a fractional electric charge, postulated as building blocks of the hadrons. Quarks have not been directly observed but theoretical predictions based on their existence have been confirmed experimentally.
- 6. nuclear force: holds most ordinary matter together because it confines quarks into hadron particles such as the proton and neutron. On a larger scale, it is the force that binds protons and neutrons (nucleons) together to form the nucleus of an atom.
- 9. the basic unit of a chemical element.
- 10. pudding model: proposed by Thomson, the atom is made of pieces with positive and negative charge, and that the negatively charged electrons within the atom were very small compared to the entire atom.
- 11. a negatively charged ion, usually formed after an atom gains one or more electrons.
- 12. is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes.
- 14. a discrete quantity of energy
- 16. number: the total number of protons and neutrons in a nucleus of an atom.
- 18. each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties
- 19. Model: proposed by Borh, states that the atom is mostly space with a small, very dense, centralized, positively charged nucleus and negatively charged electrons in specific energy levels (orbits) in the atomic space.
- 20. level: the fixed amount of energy that an electron. Energy levels are determined by the period the element is located on in the periodic table.
- 23. an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.
- 24. mass unit: a unit of mass used to express atomic and molecular weights, equal to one-twelfth of the mass of an atom of carbon-12.