1. Unit 2 Review

2. For a specific element the number of ______________ is the same but the number of ________ and ___________ may vary. Multiple forms of the same element with varying numbers of neutrons are called ________________. The same element with extra or not enough electrons are called ________. Mass number = _______________ + _______________ What are the two ways to write an isotope of carbon with 7 neutrons?  1. _______________2. _______________ Protons NeutronsElectrons Isotopes # of Neutrons# of Protons Ions Carbon-13 13 6 C

3. Name the element which has: a. 1 proton _____________ b. 4 n0, 3 p+, 3 e-________ c. 30 n0, 26 e-, 26 p+_____________ d. 18 e-, 22 n0, 18 p+_____________ Hydrogen Iron Lithium Argon

4. What are valence electrons? _____ ______________________ ______ How many valence electrons in the following atoms: a. Al ________b. P __________ c. Mg _________ The electrons in an atom’s outer most orbitals 35 2

5. How do the electron configurations for the following elements end? a. K _________b. N __________ c. Kr _________ How are mass number and atomic mass different? 4s 1 2p 3 4p 6 Mass number is the mass of the protons and neutrons combined. Atomic mass is the average mass of the element’s isotopes.

6. Describe Thomson’s experiments. Used Cathode Ray Tube Experiment to discover the first subatomic particle, the electron. Proved electron was negative by the reflection of the ray due to the placement of a negative end of the magnet

7. Describe Rutherford’s experiment. Performed the Gold Foil Experiment where he aimed positive alpha particles at a thin sheet of gold foil. He observed 1) Most particles passed through, 2) Some particles were slightly deflected and 3) Some particles bounced back. These observations proved the existence of a 1) small, 2) positive, 3) dense nucleus.

8. Why are atoms neutral? _____________________________ What is the charge of the nucleus of a Carbon atom? _____________________________ ParticleChargeMassLocation Electron Proton Neutron Approximately 0 Negative Space surrounding nucleus Positive1 Neutral1 Inside nucleus Equal numbers of negative electrons and positive protons positive

9. Complete the table: Include the mass number and atomic number in names or symbols as discussed in class. ElementSymbol#p#n#eMass #Atomic Number 49 2123 Aluminum-28 21 13 Beryllium-954 23Vanadium-444423 28 Hydrogen-2 1513 111 4

10. Complete the table: ElementElectron Configuration Orbital Notation Electron Dot Beryllium Sn (No Orbital Notation) S 1s 2 2s 2

11. Write the noble gas configuration for krypton. Also, draw the electron dot diagram.

12. Explain, in your own words ground state for electrons. Explain, in your own words excited state for electrons. Ground state electrons in the lowest possible energy level are normal. Excited state electrons take on energy and jump energy levels.

13. Why did the chemicals used in the “somewhere in the rainbow” lab give off colors when heated? The electrons absorbed the heat from the burner, causing them to jump up to the excited state. In order to return back to “ground state” the electrons must give off the extra energy – in the form of light.

14. Titanium has 5 naturally occurring isotopes. Calculate the average atomic mass. Mass (amu)% Abundance 45.9558.00 46.9527.30 47.94873.80 48.9485.50 49.9455.40

15. Sodium has two isotopes. Sodium-22 and Sodium- 23. Which is more abundant? ________________ Sodium-23

16. Accelerated Chem Only! What do the following rules tell us about electrons? Aufbau Principle electrons fill orbitals from lowest to highest energy Pauli Exclusion Princple Max of 2 electrons per orbital & they must have opposite spins Hund’s Rule For orbitals of the same energy, 1 electron per orbital and then double up