1. Rutherford’s gold foil experiment shows the mass of an atom is in the nucleus. The charge of the nucleus is positive. The volume of an atom is mostly empty space.
2. Parts of the nucleus are positive protons and neutral neutrons.
3. Electrons are found in pricipal energy level’s outside the nucleus.
4. Protons have a mass of 1 amu and a charge of +1
5. Neutrons have the same mass as a proton but no charge
6. Electrons have a mass 1/1836 the mass of a proton and a –1 charge.(no mass)
7. Atomic number = # of protons = nuclear charge
8. Atomic mass of an element = protons + neutrons. Calculate # of neutrons!
9. Atomic mass unit is based on carbon having a mass of 12. 1 amu = 1/12 the mass of carbon.
10. Isotopes are two atoms of the same element that have the same number of protons but a different number of neutrons. Therefore they have different masses.
11. Average atomic mass formula. Look it up and be able to use it.
12. Electron configurations are found in each box on the periodic table. Valence electrons are the electrons in the outermost energy level.
13. Valence electrons determine the properties of an element.
14. Orbitals are regions where electrons are expected to be located.
15. Ground state electrons are in their lowest energy level (how it appears on the table)
16. Excited electrons move to higher energy levels by absorbing energy.
17. The bright line spectrum is emitted when an excited electron returns to the ground state by releasing energy. (color is emitted; remember the flame tests)
18. Neutral atoms have the same number of protons and electrons.
19. Positive ions come from atoms losing electrons
20. Negative ions come from atoms gaining electrons
21. Atoms become ions to achieve a noble gas electron configuration. (stable octet)
22. Unreacted atoms are always neutral. Ions are atoms that have reacted.
23. Stable octet means 8 valence electrons
24. You must be able to draw Lewis structures for atoms, ions, covalent and ionic compounds.
25. Lewis structures are drawn using valence electrons only.