1. Guided Reading Ch. 2 Pgs 31-38

2. 1. Compare the planetary and Orbital Model of an atom. Pgs. 29 & 30 The planetary model of an atom views the nucleus as the sun and the electrons as planets. In this model the electrons take up fixed positions. The orbital model is more accurate because we do not know the exact position of the electrons. We only know the electrons can be found in an approximate area or orbital.

3. 2. Explain the atomic number and atomic mass number of an atom. Pg. 31 The atomic number equals the number of protons an atom contains. Since atoms have a neutral net charge the atomic # also tells us how many electrons are present in an atom. The atomic mass number equals the sum of all the protons and all the neutrons in the atom.

4. 3. Explain isotopes and how they are connected to radioisotopes and radioactivity. Isotopes of atoms have the same number of protons and electrons but a different number of neutrons.

5. Radioactivity and Radioisotopes Isotopes that have too many neutrons can be radioactive, or, emit high energy particles. (Alpha, Beta or Gamma) When atoms lose these particles we say they are decaying or have a certain radioactivity. 32 P 32 S + e 0 15 16 -1 beta

6. 4. What is the difference between a molecule and a compound. When two or more atoms are bound together chemically they are considered a molecule. When they are the same atoms bound together like H 2 then they are considered a molecule of that element. (H + H = H 2 a molecule of Hydrogen Gas) But when two or more different atoms are combined chemically then they are considered a molecule of a compound. (C + O + O = CO2 or a molecule of the compound carbon dioxide) Remember compounds have properties quite different than the atoms that make them up. Example

7. 5. Briefly explain electron shells include valence shell in your explanation. Electron shells are designated areas where electrons are found in atom. So far we have identified seven electron shells. The outer most shell is considered the valence shell and it is the only shell that is important in bonding.

8. Bonding (pg 33)

9. 6. What is the “Rule of 8s”? Atoms are “happy” when they have eight electrons in their valence shell. Atoms share, take or loss electrons to meet this rule. Also known as the Octet rule. Exception is the first electron shell that contains 2 electrons (H and He).

10. 7. Compare ionic to covalent bonds. (pg 34 & 35) Ionic bonds are formed between atoms when atoms lose or gain electrons, respectively giving the atom a positive or negative charge.

11. Covalent bonds bind atoms chemically by sharing electrons between the atoms. Covalent bonds are strong bonds.