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Unformatted text preview: Ison CH101 Name:_________, ___________ last, first Chapter 1 Worksheet Key Answer the following: 1. What are the formulas and states of matter (gas, liquid, solid) of the following elements? chlorine gas, Cl 2 oxygen gas, O 2 copper solid, Cu nitrogen gas, N 2 carbon solid, C (C 60 is another elemental form of carbon) bromine liquid, Br 2 2. A common notation used for atoms and ions is n A Z X Define A, Z and n. A – mass number, the sum of the number of protons and neutrons for the particular isotope of an atom Z – atomic number, the number of protons an atom has n – the overall charge of an atom or ion; if positive the ion has less electrons than protons, if negative the ion has more electrons than protons, if neutral the number of electrons and protons is equal and nothing is shown in the top right corner. Example: a) 15 N 3- 7 protons, 8 neutrons, 10 electrons b) 14 N 3+ 7 protons, 7 neutrons, 4 electrons c) 15 N 7 protons, 8 neutrons, 7 electrons 3. In the notation above, the value of Z is often omitted. How can you obtain that value for 4 13 + C ? What is the number of protons, neutrons and electrons for the C atom shown? Is this a cation or anion? Since Z is the atomic number (number of protons) it can be obtained from the periodic table. According to the periodic table carbon has 6 protons so since the mass number is 13 then this isotope of carbon has 7 neutrons. The number of electrons is determined from the charge of 4+. Carbon has 6 protons so this cation (positively charged ion) must have only 2 electrons to give it a 4+ charge. Ison CH101 Name:_________, ___________ last, first 4. How are two isotopes of an atom different? How are they the same? Isotopes differ in the number of neutrons only. However isotopes all have the same number of protons (atomic number). Therefore, the primary way of identifying isotopes is by the different mass number which is the sum of protons and neutrons. Example: d) 15 N 3- 7 protons, 8 neutrons, 10 electrons e) 14 N 3+ 7 protons, 7 neutrons, 4 electrons f) 15 N 7 protons, 8 neutrons, 7 electrons Note that (a) and (b) above are two different isotopes of N since they have a different mass number. However, (a) and (c) are the same isotope of N since the mass number is 15 in both cases. 5. How many eggs in one dozen? How many eggs in one mole? 12 eggs in a dozen 6.022x10 23 eggs in a mole 6. How many eggs in 5 dozen? How many eggs in 5 moles? mol in eggs dozen in eggs 5 10 . 3 5 10 022 . 6 5 60 5 12 24 23 × = × × = × The point is that a mole just represents a specific number of atoms, molecules or ions. Specifically, one mole represents 6.022x10 23 of any one item. Conversions Grams of substance Moles of substance Number of particles Molar mass (g/mol) Avogadro’s # (6.022x10 23 particles / mol ) Grams of substance Moles of substance Number of particles Molar mass (g/mol) Avogadro’s # (6.022x10 23 particles / mol ) We will use the unit factor method for conversions. The key is to set up your equation so...
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This note was uploaded on 06/06/2011 for the course CHEM 102 taught by Professor Zaowang during the Spring '08 term at N.C. State.
- Spring '08
- States Of Matter