Chemistry Test #2: Atomic Theory and the Periodic Table (KEY!) This review does not cover everything that will be on Tuesday s exam. In order to perform at your highest level, I suggest completing the following: This Review Guide Review assignments from this unit Review Notes Make flashcards as you study ASK QUESTIONS!!! The review is divided into sections for a REASON. GO BACK to your NOTES!!! 1. Using the picture above, explain Rutherford s gold foil experiment. What did the gold foil experiment tell us about the structure of the atom? Rutherford discovered the positively charged nucleus that contained protons and neutrons. 2. Draw the Bohr model for the following elements (depict protons as + and electrons as -): Fluorine Neon Circle the valence electrons in your models above. What is the definition of valence electron? Valence electrons are responsible for the bonding and creating of elements to create compounds. They are a measure of reactivity. 3. Write down Dalton s postulate that is no longer believed to be true. Explain what the postulate should say to be true. All atoms of the same element are the same. It should say: All atoms of the same element have the same number of PROTONS.
4. Compare and contrast the three types of subatomic particles in terms of location in the atom, mass, and relative charge. Electrons are the SMALLEST subatomic particle, carries a NEGATIVE charge, and are located in the ELECTRON CLOUD. Protons are LARGER than electrons, carry a POSITIVE charge, and are located in the NUCLEUS. Neutrons are the LARGEST subatomic particle; are NEUTRAL, and are located in the NUCLEUS. 5. In the space below, make a timeline for the modern atomic theory. Your timeline should include the following individuals: Dalton, Thomson, Rutherford, and Bohr. For each individual, you should write key points relating to their discovery AND how they pictured the atom (draw the individual s representation of the atom). Dalton: Wrote 5 Postulates about atoms Thomson: Plum Pudding; cathode ray tube; ELECTRONS! Rutherford: gold foil (shooting gallery experiment); Positive NUCLEUS; PROTONS and NEUTRONS! Bohr: First Model; Electron Cloud; electrons orbit around nucleus like planets orbit stars 1808 1897 1911 1912
6. Complete the following table using your knowledge of isotopes and ions Symbol Atomic Number Mass Number Number of Protons Number of Electrons Number of Neutrons 41 20 20 9 37 17 Ca F Cl +2-1 20 41 20 18 21 9 20 9 10 11 17 37 17 17 20 109 Ag 47 109 47 47 62 47 7. How are the atomic number and the number of protons related to each other? The atomic number is the number of protons in the nucleus of the atom. 8. How do the number of protons, number of neutrons, and the mass number relate to each other? The atomic mass/mass number is the total number of protons PLUS the total number of neutrons in the nucleus of an atom. 9. What is the one thing that determines the identity of an atom (that is, whether it is an oxygen atom or a carbon atom, etc.)? The atomic number or number of protons determines an atom s identity. This number NEVER changes! 10. How many protons are in the isotope 54 Cr? 24
11. How many neutrons are in the isotope 42 Ca? 12. How many electrons are in the isotope 23 Na? 22 11 13. What is the mass number of a Magnesium isotope that consists of 12 protons, 12 electrons, and 13 neutrons? 14. How many protons, electrons, and neutrons respectively does Zinc-66 have? Protons: 30 25 (12+13) Electrons: Neutrons: 30 36 (66-30) 14. Compare and contrast Mendeleev s periodic table to Mosley s Periodic table. Mendeleev s table was arranged by increasing atomic mass. Moseley s table was arranged by increasing atomic number (the one we use today). Both scientists used rows and columns to organize their tables. Additionally, they both used increasing numbers for arrangement. 15. Why do elements in the same group/family have the same chemical properties? They have the same number of valence electrons and therefore bond in the same way with the same type elements. 16. Which elements are most likely to undergo the same kinds of reactions, those in a group or those in a period? Explain your answer. Elements are arranged in groups (horizontal columns) based on their physical and chemical characteristics. So, those in the same family/group will share the same kinds of reactions. 17. Which elements are designated as noble gases? What is the most significant property of these elements? Group 18 contains the noble gases. These elements have a full set of valence electrons and do NOT bond with other elements. They are completely unreactive. 18. This group of the periodic table is highly reactive and elements are soft enough to cut with a knife Group 1, the alkali earth metals are highly reactive and soft enough to cut with a knife.
19. This group of the periodic table contains metals that exist in elemental form The transition metals all occur naturally in their elemental (pure) form. 20. This group of the periodic table contains highly reactive nonmetals The halogens are group 17 and are the most highly reactive nonmetals since they have 7 valence electrons. 21. Without using your notes, attempt to fill in the blank periodic table below. Label the alkali metals, alkaline earth metals, halogens, noble gases, and transition metals. Write in the group numbers and the number of valence electrons for the main groups. Draw in the staircase and write in where the metals, metalloids, and nonmetals are on the PT. Complete the your knowledge of the families: following table using Periodic table Periodic Table Family Alkali Metals Physical Properties Chemical Properties MOST IMPORTANT FACT Soft; solid; never found uncombined in nature (always occur in compound format) Highly reactive; explode in the presence of water; one valence electron. Highly reactive! Alkaline Earth Metals Transition Metals Solid; Same basic properties as alkali; may be found in their natural elemental form Solid; Found in their elemental form Reactive; 2 valence electrons Reactive 2-3 valance electrons Good conductors; malleable Halogens Liquid or Gas - nonmetals Highly reactive; salt formers; 7 valence electrons Salt formers; highly reactive!
Noble Gases All gases nonmetals Full set of valence electrons; do NOT bond. Always occur in elemental format in nature. 22. Identify each element as a metal or nonmetal. a) fluorine b) zinc d) phosphorous e) lithium Nonmetal Metal Nonmetal Metal 23. Give two examples of elements for each category. a) noble gases b) halogens c) alkali metals d) alkaline earth metals He; Ne; Ar; Kr; Xe; Rn F; Cl; Br; I Li; Na; K; Rb; Cs; Fr Be; Mg; Ca; Sr; Ba; Ra